23 August 2026, Volume 39 Issue 4
    

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  • Application of Artificial Intelligence in Corrosion: From Machine Learning to Large Model
    BAN Yu, GUO Xin, WANG Jinke, CHEN Zhibin, FAN Yiran, LIU Tong, MA Lingwei, ZHANG Dawei
    China Surface Engineering. 2026, 39(4): 1-21. https://doi.org/10.11933/CSE2026336
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Material corrosion is a complex degradation phenomenon that involves coupled chemical, electrochemical, and environmental interactions across multiple spatial and temporal scales. The resulting deterioration causes substantial economic losses and raises serious concerns regarding the long-term structural reliability worldwide. Conventional corrosion research has relied on long-term exposure experiments and computational simulations. Although these methods have provided valuable mechanistic understanding, their practical applications are often limited by their low efficiency, high cost, and lengthy development cycles. With the rapid growth of high-throughput experimental databases and advances in high-performance computing, data-driven corrosion research has gradually emerged as an important research direction in materials science. This review systematically summarizes recent developments in artificial intelligence for corrosion science and protective coating systems, covering both conventional machine learning (ML) techniques and emerging large-scale foundation models. First, the existing corrosion research framework is categorized into experimental approaches, including electrochemical measurements and microstructural characterization, and computational approaches, including finite element methods (FEM), Monte Carlo (MC) simulations, molecular dynamics (MD), cellular automata (CA), and density functional theory (DFT). Consequently, this review further discusses the integration of data-driven methods into corrosion prediction and material-optimization tasks. Among the traditional ML methods, artificial neural networks (ANN), deep learning (DL), support vector machines (SVM), random forests (RF), and several hybrid intelligent algorithms have shown strong predictive capabilities in different corrosion-related applications. The ANN models exhibited good nonlinear fitting performance in electrochemical impedance spectroscopy analysis, concrete durability prediction, and phase recognition of barrier coatings. DL methods, especially convolutional neural networks, have significantly improved semantic segmentation and automated defect identification in infrastructure inspection and corrosion image analysis. SVM-based models remain effective for small-sample and highly coupled nonlinear systems, particularly for pitting corrosion prediction and sulfuric acid immersion studies. Additionally, RF algorithms demonstrate robust stability and high computational efficiency when handling large historical corrosion datasets. Hybrid frameworks can further improve prediction accuracy by combining optimization strategies with conventional learning algorithms. Recent studies have indicated a growing transition from traditional ML approaches toward large pre-trained models capable of few-shot learning, cross-modal reasoning, and generative analysis. Large language models, including GPT-4o and DeepSeek-R1, have shown promising performance in corrosion inhibitor prediction by integrating molecular descriptors and simplified molecular input line entry system (SMILES) representations. Compared to conventional neural networks, these models exhibit stronger adaptability under limited data conditions. Domain-specific frameworks such as Corr-Lora-RAG further improve task accuracy while reducing storage requirements. In computer vision applications, large vision models combined with virtual data augmentation techniques enable automated corrosion-edge recognition and pixel-level segmentation with minimal manual labeling. The introduction of the segment anything model (SAM) also provides improved transferability under zero-shot and few-shot conditions. Furthermore, large multimodal models that integrate textual, visual, and geometric information are beginning to demonstrate considerable potential for structural health monitoring, corrosion damage assessment, and intelligent inspection report generation. To pave the way for future advancements, this review outlines several prospective research directions that highlight its core innovation. First, a cross-scale integrated modeling framework is discussed with the aim of connecting DFT, MD, MC, CA, FEM, and graph neural networks through large atomistic models such as DPA3. Second, a full-lifecycle domain adaptation strategy is outlined for large corrosion-oriented models, including fine-tuning, multimodal fusion, model compression, and transfer learning. Third, this study proposes an innovative approach by integrating SAM with material microstructural characterization, establishing a standardized corrosion image library and formulating specialized visual prompt strategies for material microstructure analysis. Finally, it emphasizes the necessity of establishing a collaborative mechanism to transfer universal foundational capabilities to corrosion-specific scenarios and construct specialized large-scale models for the material domain.
  • Research Progress of Resin-based Self-lubricating Materials
    ZHANG Zhongpan, FAN Xiaoqiang, ZHU Minhao
    China Surface Engineering. 2026, 39(4): 22-39. https://doi.org/10.11933/CSE2026338
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    The frictional energy consumption, wear, and corrosion failure of mechanical sliding systems are the key factors affecting the high-efficiency output and long-term safe operation of equipment. Advanced surface and interface protection technology is crucial for solving high energy consumption, high wear, and corrosion problems. With the increasing demand for efficient, energy-saving, and long-lasting mechanical systems in modern industries, the research and development of self-lubricating materials has become a crucial direction in the fields of materials science and tribology. Traditional lubrication methods, which rely on external grease or liquid lubricants, tend to fail under extreme conditions such as high temperatures, vacuum, and strong corrosion. Additionally, they cause environmental pollution and require high maintenance costs. In contrast, resin-based self-lubricating materials exhibit unique advantages in the aerospace, precision machinery, automotive manufacturing, and other fields owing to their corrosion resistance, ease of processing, and tunable tribological properties. This study systematically reviews the research progress and emerging strategies for optimizing the tribological performance of resin-based self-lubricating materials by introducing solid reinforcing fillers (two-dimensional materials, nanoparticles, fiber materials, and solid-liquid phase change materials) or liquid reinforcing fillers (lubricating oils, lubricating grease, and oil-storing microcontainers). The discussion focuses on three main themes: ① sorting and summarizing various resin-based lubrication forms, concepts, and tribological mechanisms; ② enhancing the interfacial affinity between the resin matrix and reinforcing fillers; and ③ achieving synergistic improvement in mechanical load-bearing capacity and lubrication efficiency. Finally, this study outlines the future development directions of resin-based self-lubricating materials, including intelligent response design, adaptability to harsh working conditions, multiscale simulation, and supramolecular oil gel enhancement. Recent advances in nanotechnology, surface engineering, and additive manufacturing have enabled significant progress in component design, interface optimization, and multifunctional integration of resin-based self-lubricating materials. For instance, the surface modification of fillers and polarity regulation of the resin matrix have significantly enhanced the interfacial affinity between the reinforcing phase and the resin matrix. The introduction of nanofillers not only improves the mechanical properties of the matrix but also enhances the high-temperature stability of the material through a hierarchical structure design. 3D printing technology has provided a new approach for the customized production of complex self-lubricating components. The development of novel microcontainers has enabled the construction of fine oil storage structures within resins. Furthermore, the efficient synergy between supramolecular oil gels and the resin matrix has shown promising prospects owing to the gels’ dynamic responsive lubrication properties, broad environmental adaptability, and high oil retention rates. Resin-based self-lubricating materials exhibit distinct advantages and disadvantages in two typical reinforcement methods. Solid filler reinforcement can enhance the mechanical strength of composite materials, but the intrinsic tribological properties of solid materials are limited, and uneven dispersion can easily lead to stress concentration. Liquid filler reinforcement can significantly reduce friction and is widely applicable in vacuum or sealed environments compared to traditional solid-liquid composite surface lubrication methods, but it is constrained by complex oil storage and supply structures. The core challenge in resin-based self-lubricating materials is improving the interfacial affinity between the reinforcing fillers and the resin matrix. Current research has mostly focused on the surface modification of fillers or the regulation of resin polarity to optimize stress transfer and chemical compatibility at the resin/filler interface. Future development directions should focus on the following points: 1. By integrating advanced characterization techniques (e.g., three-dimensional industrial micro-CT characterization and FIB-TEM coupling) with multiscale simulations (molecular dynamics modeling of interfacial bonding combined with finite element analysis of stress distribution), the correlations between interfacial bonding strength, interfacial sensitivity, lubricant-release kinetics, and tribological performance will be elucidated. A “phase diagram” linking the resin matrix, reinforcing fillers, and tribological performance will be constructed to provide a fundamental basis for component matching design and structural optimization. 2. Development of smart self-lubricating materials with both strong interfacial bonding and weak interfacial slippage for responsive lubricant release, while balancing mechanical load-bearing capacity and lubrication efficiency through multiscale interface engineering (such as the “soft+hard” strategy and hierarchical structure design strategy mentioned earlier), to enhance the multi-operational stability of self-lubricating resin materials. 3. The integration of resin-based self-lubricating materials with supramolecular organogels offers a new approach to addressing the critical bottlenecks in conventional oil-based resin self-lubricating systems. Compared with traditional microcapsules, this technology avoids issues such as irreversible shell rupture and nonuniform size distribution, and its self-healing properties can extend the lubrication life. In the future, the combination of supramolecular organogels with resin matrices is expected to enable the development of next-generation self-lubricating materials with high load-bearing capacities, low friction, and long service lives.
  • Research Progress on Solid Interfacial Structure Engineering and Lubrication Mechanisms in Solid-liquid Synergistic Superlubricity
    CHEN Jinyan, WANG Ru, SUN Han, LI Jinjin
    China Surface Engineering. 2026, 39(4): 40-56. https://doi.org/10.11933/CSE2026337
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    Conventional solid superlubricity is highly sensitive to environmental conditions and is difficult to sustain under ambient atmosphere. Liquid superlubricity, although effective in air, often suffers from poor load-bearing capability owing to the thermodynamic instability of liquid lubrication films under high contact pressure. These limitations significantly hinder large-scale engineering applications of superlubricity and necessitate the development of alternative lubrication strategies. Solid-liquid synergistic superlubricity, an emerging lubrication paradigm developed in recent years, has attracted much interest because of its potential to overcome the intrinsic limitations of conventional solid and liquid superlubricity systems, particularly in terms of environmental adaptability and load-bearing capacity. This strategy relies primarily on the rational pairing of solid lubricating materials and liquid lubricants through friction tests, followed by performance optimization via approaches such as chemical modification and interfacial engineering. By integrating the advantages of both solid and liquid lubrication, solid-liquid synergistic superlubricity provides a promising route for achieving stable, durable, and ultralow-friction states under complex operating conditions. Owing to the diversity of lubricating materials and the complexity of tribochemical reactions, solid-liquid synergistic superlubricity has evolved rapidly in recent years, resulting in various lubrication systems and realization pathways. In this context, this review systematically summarizes the recent advances in interfacial structure engineering and lubrication mechanisms in solid-liquid synergistic superlubricity. First, solid and liquid superlubricity systems are analyzed comparatively to clarify their respective advantages and limitations in terms of contact pressure, environmental adaptability, and lubrication stability, thereby highlighting the necessity of synergistic design. Based on this, the fundamental mechanisms governing solid-liquid synergistic superlubricity are comprehensively analyzed. We reveal that the superlubricity behavior is dominated by the coupled effects of tribochemical reactions, interfacial adsorption, and the evolution of low-shear structures. In particular, tribochemical reactions induced by the interaction between solid surfaces and lubricant molecules play a critical role in the formation of tribofilms with enhanced mechanical stability and low shear strength. Furthermore, the mechanisms regulating lubrication performance via solid interfacial engineering are systematically discussed. The roles of two-dimensional layered materials, quantum dot materials, and functional coatings in achieving superlubricity are critically reviewed. The structural characteristics, surface functional groups, and interfacial energies of these materials significantly influence their adsorption behavior, dispersion stability, and tribochemical activity, thereby determining the formation and stability of lubricating films. Special focus is given to the structure-property relationships governing the entry of nanomaterials into the contact interface, their interaction with lubricant molecules, and their contribution to friction reduction. In addition, to investigate the current limitations of solid-liquid synergistic superlubricity and provide guidance for further expanding its industrial application potential, we analyze in detail the failure mechanisms of solid-liquid synergistic superlubricity under extreme conditions, such as high loads and elevated temperatures. The breakdown of lubrication films, interfacial oxidation, and friction-induced thermal accumulation are identified as the primary factors leading to the loss of superlubricity. Correspondingly, potential strategies for enhancing superlubricity performance are proposed, including optimizing the interfacial chemical reactivity, improving the mechanical robustness of tribofilms, and designing multi-component lubrication systems. Finally, future research directions are proposed from both the fundamental and engineering perspectives. For industrial applications, the development of superlubricity systems with high load-bearing capacities and long service lives should be emphasized. From the perspective of mechanistic investigation, greater attention should be devoted to implementing in situ and multiscale characterization techniques to elucidate dynamic interfacial processes, as well as to the establishment of standardized evaluation criteria for practical applications under complex operating conditions. This review provides a comprehensive understanding of solid-liquid synergistic superlubricity and offers theoretical guidance for its further development and industrial implementation.
  • Research Progress on the Structure and Materials of Environmental Barrier Coatings for Ceramic Matrix Composites
    ZHAO Junkun, LIANG Shuaishuai, QI Bin, WANG Changliang, DU Xiuxin, CHEN Haosheng
    China Surface Engineering. 2026, 39(4): 57-74. https://doi.org/10.11933/CSE2026188
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    The rapid advancement of aerospace engine technology has significantly increased the demand for ceramic matrix composites (CMC) in high-temperature applications. However, the severe corrosion of CMC in such environments-particularly in the presence of water vapor and oxygen-presents a substantial challenge to their long-term performance. Environmental barrier coatings (EBC) have emerged as a vital solution to protect CMC from these corrosive conditions, enabling their use in the hot-section components of advanced aerospace engines. The evolution of EBC materials and structures is marked by the transition from single-layer to multi-layer systems, with key advancements aimed at improving performance under extreme operating conditions. Initially, EBC systems were based on mullite, which provided early-stage protection but was vulnerable to corrosion from water vapor. The introduction of yttria-stabilized zirconia (YSZ) as a surface layer offered enhanced corrosion resistance. However, the thermal expansion mismatch between YSZ and mullite led to cracking, compromising durability. In the second generation of EBC, barium-strontium-aluminosilicate (BSAS) coatings demonstrated better compatibility with thermal expansion and improved corrosion resistance. Nevertheless, BSAS coatings were limited by their lower melting points and susceptibility to degradation under high-temperature gas flows. Recent advancements have focused on third-generation EBC, particularly the incorporation of rare-earth silicates. These materials are characterized by superior high-temperature stability, low thermal conductivity, and excellent resistance to corrosion. Rare-earth monosilicates (RE2SiO5) and disilicates (RE2Si2O7) have shown promise in protecting CMC from water vapor and CMAS (calcium-magnesium-aluminosilicate) corrosion. The development of high-entropy rare-earth silicates, which integrate multiple rare-earth elements, has further enhanced their thermal and mechanical properties. These advanced materials exhibit lower thermal conductivity, improved phase stability, and enhanced CMAS resistance, making them strong candidates for the next generation of EBC systems. In addition to surface and intermediate layers, the importance of bond coats in EBC systems is also crucial. Traditional silicon (Si) bond coats, while effective at lower temperatures, suffer from limitations such as a low melting point and the formation of thermally grown oxide (TGO) layers, which can lead to coating failure under thermal cycling. Innovations in bond coat materials, such as Si-HfO2 and Si-Yb-Gd composites, have addressed these challenges by improving high-temperature stability and reducing TGO formation. These advanced bond coats not only improve adhesion between the EBC and CMC substrate but also provide enhanced protection against oxidation and corrosion. The performance of EBC systems is further influenced by their structural design. Multi-layer architectures, including bond coats, intermediate layers, and surface layers, are optimized to balance thermal expansion coefficients, chemical compatibility, and mechanical properties. For instance, rare-earth disilicates are often used as intermediate layers due to their close thermal expansion match with CMC substrates, while monosilicates serve as surface layers for their superior corrosion resistance. The integration of computational modeling and machine learning techniques offers a promising approach to accelerate the discovery and optimization of new EBC materials, enabling the design of coatings with tailored properties for specific operational conditions. Despite these advancements, challenges remain in the development of EBC for ultra-high-temperature applications. The interaction between EBC layers and CMC substrates under thermal cycling, the long-term stability of high-entropy materials, and the mitigation of CMAS corrosion require further investigation. Future research should focus on exploring novel material combinations, refining coating deposition techniques, and understanding degradation mechanisms under realistic engine conditions. Recent advancements in EBC technology have charted a clear development path for aerospace applications. A systematic analysis of multilayer EBC systems, coupled with an in-depth exploration of high-entropy materials' potential, has laid the groundwork for next-generation high-performance coatings. The ongoing refinement of EBC technology represents a critical enabler for next-generation high-efficiency, high-thrust aero engines, ensuring their reliable operation and extended service life under extreme conditions.
  • Research Progress on Composition Design and Preparation Technology of NiAl and MCrAlY Bond Coats for Thermal Barrier Coatings
    LIU Jiahang, LÜ Zhe, XU Zhen, WANG Yiyong, LI Yan, ZHOU Yanwen
    China Surface Engineering. 2026, 39(4): 75-99. https://doi.org/10.11933/CSE2026128
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    Thermal barrier coatings are currently the most widely used technology for cooling the hot-end components of turbine engines. They are used in a wide range of industries, including aerospace, automotive, marine, and large-scale thermal power generation. These coatings are characterized by a low thermal conductivity, high coefficient of thermal expansion, excellent mechanical properties, and good corrosion resistance. A thermal barrier coating consists of four parts: a top coat, a bond coat, a metal substrate, and a thermally grown oxide. Among them, the bond coat, as the intermediate layer of the thermal barrier coating system, improves the oxidation and corrosion resistance of the metal substrate and the bonding strength of the ceramic coat. Therefore, the thermal expansion coefficient, high-temperature oxidation resistance, and thermomechanical properties of the metal bond coat directly affect the performance and thermal cycle life of the thermal barrier coating system. Thermal barrier coatings with NiAl and MCrAlY bond coats have good high-temperature oxidation resistance, which can extend their service life. The development of bond coats with excellent performance has become a research hotspot, achieved through composition design, high solid solubility element doping, active rare earth element doping, oxide doping, and high-entropy composition design. Furthermore, the internal microstructure of the coating, and porosity related to the preparation process of the performance of the bond coat plays a decisive role in the bond coat. With the rapid development of a new generation of high-temperature alloys, there is a need to develop binder-layer materials that meet high-temperature service requirements. At present, the development of first-principles calculations, computer simulations, and simulation technology, and material genetic engineering, provide new research methods for the design of binder layer compositions, structures, and performance characterization. The combination of material computation and binder layer composition design has become a future development trend; however, few studies have been conducted on this aspect. In the preparation of the bond coat of thermal barrier coatings, the main preparation technology is air plasma spraying, which is characterized by high deposition rate, simple operation, and low cost. However, the internal part of the prepared bond coat often contains numerous defects, such as cracks and pores, which weaken the high-temperature antioxidant performance of the bond coat. This review summarizes the advanced preparation methods for thermal barrier coatings, including explosive spraying, cold gas power spraying, and supersonic flame spraying. At present, there are insufficient preheating and post-heating phenomena in the preparation of bonding layers by thermal spraying, and it is not possible to fully grasp the preheating temperatures of the substrate and the powder spraying parameters required for different bonding layer materials. This leads to the risk of uneven solidification of powder droplets, high residual stresses, and overheating of the bonding layer during the preparation of the bonding layer. Therefore, it is necessary to combine it with computer modeling to provide accurate process control of the thermal spraying process by simulating the heat source and solidification behavior of the powder droplets during the thermal spraying process. This provides a suitable method for the preparation of different metal bonding layers; however, few studies have been conducted on this aspect. The development of new materials for thermal barrier coating bond coat and advanced preparation methods is crucial for meeting the requirements of future turbine engines with high service temperatures. From the perspective of compositional doping, several typical compositional design approaches for NiAl and MCrAlY bond coats are summarized. Moreover, the optimization mechanisms of different composition designs on bond coat properties and current issues are described. From the perspective of the preparation method, different bonding layer preparation methods are introduced and summarized in terms of preparation principles, bond-coat microstructure, and performance. Finally, the future development direction of the composition design and preparation technology for NiAl and MCrAlY is envisioned to provide a theoretical basis for the development of new-generation thermal barrier coatings with better antioxidant and mechanical properties.
  • Progress in the Preparation of Ceramic Coatings by Slurry Method
    JI Yanzhe, CAO Yupeng, WANG Quansheng, LI Zhiqiang
    China Surface Engineering. 2026, 39(4): 100-114. https://doi.org/10.11933/CSE2026189
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    Ceramic coatings are widely used across various industries, including energy, aerospace, automotive, and medical devices, due to their exceptional properties such as high-temperature resistance, oxidation resistance, and corrosion resistance. These coatings are essential for enhancing the performance and durability of components operating under harsh conditions. Among the various fabrication methods for ceramic coatings, the slurry method has gained increasing attention in recent years owing to its advantages, including low cost, process flexibility, and broad applicability. However, systematic studies on this method remain limited, and a comprehensive review summarizing its applications in ceramic coating preparation is lacking. This paper presents a comprehensive review of recent research progress on the slurry method for preparing ceramic coatings. The process involves mixing ceramic powders with binders and other additives to form a slurry, which is then applied to a substrate and subjected to heat treatment. After heat treatment, the slurry solidifies into a robust ceramic coating with desirable properties. This review discusses the fundamental working principles of the slurry method, outlines its process characteristics, and highlights key factors that influence coating performance. Critical parameters such as solid content, binder type and concentration, coating application techniques, and heat treatment conditions are examined in detail. Their effects on the microstructure and properties of the coatings, including density, adhesion strength, and functional performance, are analyzed. In particular, the sintering temperature and holding time are emphasized for their significant influence on phase transformation, bonding strength, and the formation of specific phases within the coating. Higher solid content generally leads to denser coatings with improved adhesion and overall performance. Binder selection plays a crucial role in determining slurry rheology and coating uniformity, while binder content must be carefully optimized to balance slurry viscosity and final coating quality. Various application methods such as spraying, dipping, and brushing are discussed, as they affect slurry distribution and the uniformity of the resulting coatings. The heat treatment process is critical for determining phase composition, bonding strength, and coating durability. This review also explores how different sintering profiles affect microstructure, including grain growth, porosity, and phase evolution. Beyond fundamental parameters, the challenges of applying the slurry method in extreme environments, such as the high temperatures found in aerospace engines. The ability of ceramic coatings to maintain their structural integrity under such conditions is essential, highlighting the need for developing advanced ceramic materials with high melting points, low thermal conductivity, and excellent chemical stability. The use of novel binders and high-temperature-resistant ceramic powders is identified as a promising research direction. Strategies to enhance the thermal stability of coatings include optimizing material selection and refining heat treatment processes to prevent degradation. This review also discusses the role of slurry formulations in improving the coatings' thermal insulation, corrosion resistance, and wear resistance. Recent developments in slurry preparation techniques and advanced sintering processes are emphasized. Furthermore, the integration of emerging technologies such as automated spraying systems and 3D printing-assisted deposition is explored. These innovations enable precise coating applications on complex geometries, expanding the industrial applicability of the slurry method. In conclusion, this review provides a thorough analysis of slurry-based ceramic coating fabrication and summarizes the latest research and technological advancements. The findings offer valuable insights into optimizing process parameters and formulations to achieve high-performance coatings. This work is expected to serve as a critical resource for researchers and engineers in the field, guiding future developments in ceramic coating technology.
  • Shape Optimization of Surface Texture
    ZHANG Chenpu, YANG Huiya, LÜ Tian, HUANG Wei, DAI Qingwen, WANG Jingqiu, WANG Xiaolei
    China Surface Engineering. 2026, 39(4): 115-132. https://doi.org/10.11933/CSE2026121
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    Surface texturing has significantly advanced over the past three decades as a critical strategy for improving tribological performance, particularly in reducing friction and wear. The shape of individual texture units is a key factor influencing surface function. By leveraging machining marks to design and control texture geometries, and with the aid of microfabrication technologies, researchers have continued to optimize texture shapes. It is established that surface textures can both reduce and increase friction. Therefore, only appropriate designed textures yield the desired tribological benefits, while poorly designed ones can be detrimental. This has driven extensive research into optimizing texture shapes and parameters to meet specific tribological needs, a task that remains challenging. This review summarizes progress in surface texture shape optimization from three perspectives: the evolution of texture geometries, underlying optimization principles, and the application of optimization algorithms. Early studies focused on simple geometric patterns, categorized as either discrete textures (e.g., circular, triangular, rectangular, or hexagonal dimples) or connected textures (e.g., continuous grooves arranged in parallel or crosswise). More complex composite textures have emerged by combining these regular forms. Meanwhile, biomimetic designs, modeled after nature’s evolved textures, have introduced greater geometric flexibility and improved performance. Inspired by this, by using parametric optimization methods, people began to design free-shape textures that were not restricted by the initial shape, in order to further enhance the tribological properties of the surface texture. The primary goal of surface texturing is to achieve low friction under full-fluid lubrication, with the hydrodynamic effect often serving as the dominant design principle. For example, in groove-type textures, the angle relative to the sliding direction significantly influences internal fluid, affecting lubricant supply and leakage. Temperature fluctuations also alter lubricant rheology, impacting performance. Additionally, elastic deformation of contact surfaces is influenced by the combined effects of hydrodynamic pressure, texture geometry, and lubricant viscosity. As a result, optimization strategies are shifting from single- mechanism approaches to multi-mechanism strategies. As research progresses from simple to biomimetic and free-form textures, and from single-to multi-objective optimization, the number of influencing parameters has increased dramatically. This has introduced challenges such as the “curse of dimensionality” and susceptibility to local optima. To address this, intelligent algorithms, such as sequential programming, topological optimization, and genetic algorithms, are increasingly employed. More recently, artificial intelligence and deep learning have emerged as powerful tools in this domain, marking the rise of a fifth research paradigm (data-driven science). While current applications are still emerging, these methods have demonstrated high efficiency and great potential. The optimization of surface texture shapes is an ongoing evolutionary process. Compared to nature’s 3.5 billion years of surface design, current efforts are just beginning. As scientific understanding deepens, novel functional textures—such as diode-like channels, wedge structures, and fishbone patterns leveraging Laplace pressure for unidirectional fluid transport, are being developed, further expanding the possibilities for surface texture design.
  • Research Status of Underwater Welding Repair Technology for Nuclear Power Equipment
    ZHU Jialei, QI Shikong, ZENG Caiyou, LI Shougen, ZHANG Hongtao, LI Zhehui, WANG Chengyuan, LIU Pengbo
    China Surface Engineering. 2026, 39(4): 133-149. https://doi.org/10.11933/CSE2026327
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    The high-quality repair and life extension of nuclear power equipment are essential to ensure the safe and economical operation of nuclear power plants. With the global expansion of nuclear energy and nearly half of all reactors operating for more than 30 years, the degradation of key components due to irradiation embrittlement, thermal fatigue, and stress corrosion cracking has become increasingly severe. Conventional repair methods which involve draining the reactor coolant and installing large encapsulation systems can lead to high radiation exposure, prolonged shutdowns, and significant economic losses. Underwater welding repair technology is considered a promising solution for the in-situ restoration of nuclear components, enabling localized metallurgical bonding and sealing reinforcement directly in the reactor’s water environment to effectively reduce radiation exposure and downtime. This approach is particularly advantageous in areas where traditional dry repair methods are impractical, such as maintaining reactor pressure vessels and spent fuel pools. Underwater welding is classified into three types: wet, high-pressure dry, and local dry welding. Wet welding is performed directly underwater using an arc gas bubble or laser vapor cavity to isolate the molten pool, offering high flexibility and suitability for rapid repairs. However, water flow and pressure fluctuations can lead to porosity, cracking, and hydrogen embrittlement. High-pressure dry welding is conducted in a sealed hyperbaric chamber that simulates air conditions to produce high-quality welds with excellent mechanical properties. However, complex equipment, high cost, and large size limit its use in confined nuclear environments. Local dry welding combines the benefits of both methods using a miniature drainage hood and shielding gas to create a controlled micro-dry zone, ensuring stable welding quality in narrow or complex spaces. Because of its flexibility and adaptability, it is the preferred method for underwater nuclear maintenance. From the perspective of energy sources and process mechanisms, underwater welding technologies are mainly classified into arc- and laser-based methods. Arc welding, such as shielded metal arc welding and flux-cored arc welding, efficiently converts electrical energy into heat, making it suitable for stainless steels and nickel-based alloys used in nuclear structures. Recent advances in pulsed arc control and adaptive waveform modulation have improved droplet transfer, reduced porosity, and enhanced the resistance to pressure. Laser welding employs high-energy-density beams for deep penetration and precise energy delivery. Optimized drainage hoods and beam transmission paths help mitigate plasma shielding and vapor disturbances. Experiments under simulated depths of up to 0.5 MPa demonstrate that underwater laser welding can produce dense, defect-free, and high-strength joints, showing great potential for high-pressure structural repairs. Automation and intelligentization are key trends in the development of nuclear underwater welding. The integration of robotic systems and remote control ensures safe, accurate, and efficient operations in radioactive or deepwater environments. Automated local dry-welding systems equipped with real-time monitoring and dynamic cavity control can maintain stable welding conditions while reducing radiation exposure. Furthermore, combining laser welding with multi-degree-of-freedom robotic manipulators enables high-precision repairs in confined reactor areas with complex geometries. Artificial intelligence (AI) is expected to further advance underwater repair technology, with AI-driven algorithms optimizing parameters, predicting defects, and planning welding paths adaptively to create an integrated “inspection-repair-evaluation” loop. These developments will improve weld quality, consistency, and reliability while reducing human intervention and risks. In summary, underwater welding repair technology has evolved from traditional wet welding to advanced hybrid processes that integrate local dry environments, high-energy beams, and intelligent robotics. These innovations provide reliable and economically feasible solutions for extending the service life of nuclear power components. The continuous development of automated and intelligent underwater welding systems is crucial for establishing a safe, sustainable, and intelligent maintenance framework for next-generation nuclear power plants.
  • Advances in the Mechanism of Lubricant Infiltration Dynamics and Enabling Technologies at the Tool-workpiece Interface
    WU Libin, ZHANG Yanbin, ZHANG Rukang, CUI Xin, QU Shuoshuo, YANG Yuying, YIN Qingan, ZHANG Wenqiang, ZHOU Zhigang, BIE Qingfeng, YIN Xianxin, LI Changhe
    China Surface Engineering. 2026, 39(4): 150-180. https://doi.org/10.11933/CSE2026158
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    In metal cutting processes such as turning, milling, drilling, and grinding, tribological interactions at tool-workpiece interfaces are universally acknowledged as critical determinants of tool longevity and machining accuracy. Simultaneously, the wetting behavior and performance-enhancing techniques of lubricants are recognized as pivotal for reducing interfacial friction and wear. However, significant challenges persist in achieving consistent wetting performance during ultra-precision machining, where complex interfacial geometries and dynamic operational conditions introduce unpredictable lubricant spreading patterns. The wettability characteristics of lubricants at these interfaces are governed by an intricate interplay of physicochemical properties, including viscosity, thermal stability, and surface tension, alongside cutting parameters such as speed, feed rate, and depth of cut. Workpiece material properties, ranging from metallurgical composition to phase distribution, further modulate interfacial energy states, while surface roughness variations create microscale topographies that either promote or hinder lubricant infiltration. These multifaceted interactions collectively result in wetting phenomena that resist straightforward characterization or prediction. Capillary infiltration mechanisms, forming the theoretical foundation of lubricant penetration into narrow interfacial gaps, remain partially understood despite their critical role in precision machining applications. Uncertainties persist regarding the dominance of capillary forces over viscous resistance during microscale fluid transport, particularly when surface adsorption effects and molecular interactions become significant at near-atomic scales. These knowledge gaps are exacerbated by the growing adoption of sustainable machining practices, where reduced lubricant volumes and alternative cooling strategies fundamentally alter traditional wetting dynamics. Consequently, systematic investigations are prioritized to evaluate lubrication methodologies while elucidating wettability enhancement mechanisms under ecological manufacturing constraints. Current research trends and developmental priorities in lubricant wetting are identified through quantitative bibliometric analysis, enabling objective mapping of technological advancements and emerging innovation pathways. Critical literature is categorized to establish foundational references for technical discussions, revealing three dominant sustainable lubrication strategies: minimum quantity lubrication, nanofluid minimum quantity lubrication, and water vapor applications. These approaches are comparatively analyzed through the lens of multiphase flow dynamics and capillary wetting models. In minimum quantity lubrication systems, parametric influences of oil mist generation parameters—including air pressure, nozzle geometry, and flow rate—are investigated for their impacts on aerosol deposition uniformity and interfacial spreading efficiency. Nanofluid minimum quantity lubrication implementations are distinguished by nanoparticle-mediated wettability modifications, where engineered nanomaterial properties such as size distribution, morphological characteristics, and surface functionalization are demonstrated to synergistically alter contact angle dynamics and surface energy equilibria. Cryogenic cooling methodologies are examined for their dual functionality in thermal management and tribology reaction suppression, with low-temperature media observed to elevate lubricant viscosity while inhibiting thermally activated adhesion mechanisms. Water vapor lubrication systems are characterized by phase-change heat transfer capabilities, where rapid vapor condensation at tool-chip interfaces facilitates cooling efficiency and boundary lubrication through controlled oxide layer formation. Tool design considerations are systematically evaluated across three dimensions influencing lubricant transport and retention. Geometric parameters, particularly edge radius and rake angle variations, are correlated with chip formation patterns and resultant lubricant entrainment dynamics. Micro-textured surface architectures are demonstrated to enhance capillary-driven lubricant distribution through precisely engineered groove patterns that optimize fluid retention and directional flow. Advanced coating technologies are verified to modify interfacial wettability through selective adsorption and repulsion behaviors, with surface energy modulation identified as the primary mechanism governing lubricant-substrate affinity. These design elements collectively determine lubricant accessibility to critical wear zones, directly impacting tool performance and machining precision. Energy field-assisted wettability enhancement techniques are categorized based on their operational principles and scale of influence. Ultrasonic vibration implementations are characterized by high-frequency pressure modulation effects that simultaneously reduce lubricant molecular aggregation and promote capillary infiltration through dynamic surface interactions. Magnetic field applications enable precise nanoparticle trajectory control in ferromagnetic nanofluids. It has been demonstrated that electrostatic fields can reduce droplet size through charge-induced Rayleigh instability, as well as modulate contact angle through electro-wetting phenomena on the dielectric.
  • Research Progress in Surface Treatment Technology of Soil-engaging Components of Agricultural Machinery
    LI Mingxi, LI Ming, HUANG Haibo, LUO Jianghe, XIE Xiaoming, WANG Zhiwen, LIU Xiubo
    China Surface Engineering. 2026, 39(4): 181-198. https://doi.org/10.11933/CSE2026152
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    Agricultural soil-engaging components, as the final link in the power transmission of agricultural machinery, frequently and directly interact with soil during operation, leading to wear, corrosion, and fracture, which are forms of failure. Frequent failure can result in extended maintenance times, decreased production efficiency, increased energy consumption, environmental pollution, and impacts on agricultural timing, causing significant economic losses and hindering the rapid development of agricultural mechanization. Enhancing the hardness, wear resistance, and toughness of soil-engaging components through surface treatment technologies can extend their service life and reduce the likelihood of environmental pollution caused by partial flaking and fracture. However, the quality of surface treatment processes is influenced by various factors, including the composition and structure of the substrate material and its pretreatment process, composition and arrangement of the coating precursor, type and parameter control of the surface treatment process, working mode of the components, and soil environment conditions—these factors interact to form a complex system. Systematic discussions on research in this field are relatively limited. This article reviews the current status of research on the main surface treatment technologies, focusing on the failure mechanisms of soil-engaging components, and summarizes aspects such as process characteristics, precursor materials, coating bonding methods, enhancement effects, and applicable scenarios. The protective mechanism of the surface treatment technology is elucidated, and the advantages and disadvantages of the different treatment processes applied to different soil-engaging components are compared. The main modification technologies for the surface enhancement of soil-engaging components include cladding, thermal spraying, and surface heat treatment. Cladding has unique features, such as flexible processes, wide material adaptability, stable processes, high powder-utilization rate, high bonding strength, and suitability for field construction. The cladding layer can achieve metallurgical bonding with the substrate, with a coating thickness of up to 2 mm and microhardness of >1 000 HV, and is widely used for critical component repair. Thermal spraying technology uses a high-speed gas to spray a molten or semi-molten precursor powder onto the surface of a component, where it cools and solidifies to form a functional coating. This bonding method is primarily based on mechanical interlocking, which is characterized by simple processes, strong adaptability, low thermal input to the substrate, and adjustable coating thickness. Heat treatment technology is well established in the field of surface modification. The surface chemical composition and microstructure were controlled by changing the temperature, time, and treatment medium to enhance surface performance. Its main features include simple operation and high production efficiency. A systematic analysis of the strengths and weaknesses of the three aforementioned processes was undertaken, with recommendations for future work tailored to the current agricultural production scenario in China, which involves multiple regions and diverse crops. First, basic research on soil models should be encouraged, given the considerable variations in soil moisture, hardness, and pH levels across different areas. Therefore, it is imperative to develop suitable structures and surface treatment techniques for soil-engaging components according to specific soil conditions. Second, the development of new material systems and surface modification processes should be considered comprehensively, including soil conditions, power output forms, transmission methods, and forces exerted during the cutting and crushing of soil blocks using tools. Finally, the establishment of a database of the structural design and surface treatment processes of soil-engaging components would offer systematic technical support for their design. Enhancing the operational effectiveness of soil-engaging components while maintaining costs within an acceptable range is paramount. This approach is crucial for achieving highly efficient agricultural production and resource utilization and advancing agricultural mechanization.
  • Research Progress on Fluid-solid Interface Wettability for Flow Drag Reduction in Crude Oil Pipeline Transportation
    WANG Shuai, NIU Beiyuan, WU Wenxia, YIN Ran, XIN Baoyan, BAI Jiangang, XIAO Kun, XU Li
    China Surface Engineering. 2026, 39(4): 199-215. https://doi.org/10.11933/CSE2026190
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    With the continuous expansion of unconventional high-viscosity crude oil exploitation, the issue of low transportation efficiency—caused by strong adhesion and high resistance during pipeline flow— has become increasingly prominent. As the core mechanism for addressing this problem, the wettability of the fluid-solid interface has not yet been systematically summarized in theory to guide engineering practice. Wettability directly influences adhesion behavior and flow characteristics at the interface between crude oil and the pipe wall. Adjusting wettability can significantly reduce flow resistance during pipeline transportation, thereby greatly improving efficiency. This study provides a detailed description of research methods related to rock wettability formation, such as contact angle measurement, nuclear magnetic resonance, and numerical simulation. It highlights that current research on the wettability of formation rocks mainly focuses on influencing factors, the impact of wettability on fluid flow behavior, chemical modification techniques, and related topics. The significance of these studies in understanding fluid-solid interface behavior in pipeline transportation is also analyzed. Additionally, the study summarizes current research methods and recent advances in the field of fluid-solid interfaces and fluid wettability. It emphasizes the importance of integrating experimental approaches with numerical simulations in wettability studies. Furthermore, it discusses interface modification technologies and their influence on flow behavior , revealing the critical role of wettability in pipeline transportation. The main factors affecting wettability at the fluid-solid interface are analyzed in detail, including solid properties (e.g., wall material, surface roughness, and chemical composition), fluid properties (e.g., chemical composition, viscosity, and surface tension), and external environmental conditions (e.g., temperature and pressure). Optimizing these factors can significantly alter fluid viscosity, achieve a more favorable velocity distribution in the pipeline, and reduce turbulence intensity—thereby improving internal flow characteristics. Additionally, surface slip behavior can be enhanced by reducing frictional resistance, increasing boundary slip, and optimizing flow modes, ultimately improving flow performance and transport efficiency. In addition, this study reviews the application of wettability in pipeline flows and analyzes the roles of surface modification technologies and surfactants in wettability regulation. Surface modification can effectively reduce adhesion resistance between the fluid and pipe wall by altering surface properties—such as enhancing hydrophobicity or lipophilicity—and significantly improving fluid mobility. Surfactants can substantially modify the surface tension and contact angle of a fluid, enabling wetting reversal from hydrophobic-lipophilic to hydrophilic-oleophobic. This transformation reduces the adhesion force between the fluid and the pipe wall, minimizes energy loss, and improves overall transport efficiency. Studies have shown that both approaches not only enhance fluid flow behavior but also extend pipeline service life and reduce maintenance costs. Based on the multidimensional coupling of solid surface characteristics, fluid composition, and environmental parameters, this study constructs a theoretical framework for wettability regulation. It reveals the synergistic effects of interfacial modification and surfactants on wettability reversal and resistance reduction. Finally, a quantitative drag reduction strategy based on multifactor correlations is proposed, filling the existing gap in systematic research on wettability.
  • High-speed Laser Cladding of Cu-based Ti / Nb Layered Structures with Uniform Arc Erosion Behaviors
    GUAN Weimian, LIU Yanmei, LIANG Xinzeng, ZHAO Liang, GUAN Feng, JIA Dawei, LIU Jiabin
    China Surface Engineering. 2026, 39(4): 216-226. https://doi.org/10.11933/CSE2026191
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    Laser cladding is an efficient method for the surface modification of metallic cathodes; however, the choice of an erosion-resistant layer and the corresponding laser cladding process remain unclear. Currently, arc erosion is the primary factor limiting the service life of metallic cathodes, negatively impacting the operational stability of arc plasma devices. Surface-modified cathodes made via laser cladding combine the benefits of an erosion-resistant surface with a highly conductive substrate, effectively enhancing overall cathode performance. In this study, Ti and Nb were selected as the surface and intermediate layers, respectively, on a Cu substrate. These layers were deposited sequentially using a high-speed, layer-by-layer laser cladding process. At a laser power of 3.6 kW and a scanning speed of 0.09 m / s, the Nb layer was metallurgically bonded to the Cu substrate. Then, the Ti layer was laser cladded onto the Nb surface at 2.0 kW and 0.025 m / s. The total thickness of the Ti / Nb claddings reached approximately 1850 μm, with the Ti layer measuring about 900 μm. The cladding’s composition, microstructure, and phases were characterized. The Ti cladding, consisting entirely of hexagonal close-packed (hcp) Ti, had a high Ti content of 94.9 at.%. The Nb cladding, composed of 96.6 at.% Nb and 3.4 at.% Cu, was a mixture of body-centered cubic (bcc) Nb and face-centered cubic (fcc) Cu. The presence of a high surface Ti content without intermetallic compounds indicated the blocking and transition role of the Nb layer. The Nb intermediate layer suppressed Cu dilution into the Ti layer, preventing brittle intermetallic formation and preserving the plasticity of the layered Ti / Nb structure. The arc discharge and erosion behavior of the Ti / Nb-layered cathodes were tested using a cathode erosion system. Compared to Cu cathodes, Ti / Nb cathodes exhibited more uniform arc discharge and erosion behavior. Their erosion surfaces were relatively smooth with only some cracks, indicating improved erosion resistance. In contrast, Cu cathodes showed deep, overlapping erosion craters at discharge centers, reflecting typical inhomogeneous erosion. Crater formation from type Ⅱ cathode spots can cause severe erosion and significant material loss. The Ti / Nb layered cathode’s discharge surface was composed mainly of numerous type Ⅰ cathode spots, fast-moving spots with short lifetimes causing moderate erosion. The formation of type Ⅰ spots was attributed to a surface nonmetallic oxide layer. Characterization of eroded cathodes revealed in situ formation of a titanium oxide (TiO₂) layer. The erosion center featured a layered structure consisting of a surface oxide layer, a dual-phase layer, and a bottom Ti layer. The TiO₂ layer began forming during initial discharge and stabilized at around 30-40 μm thickness. Compared to the Ti layer, the refractory TiO2 layer, with its higher melting point and lower work function, improved electron emission and protected the underlying cathode. A balance between erosion loss of the surface TiO2 and replenishment from Ti oxidation ensured sustainable, homogeneous erosion behavior. The Ti / Nb cathodes also demonstrated improved arc erosion resistance, with an erosion rate of 1.54 μg / C, 30.6% lower than Cu. The eroded surface showed gentle height variations and no evident pits, with a maximum erosion depth of only 94.8 μm. The enhanced discharge homogeneity and arc erosion resistance of the Ti / Nb cathodes were attributed to the in situ formed TiO2 layer. This improvement makes the Ti / Nb cathode a promising candidate for future metallic cathodes.
  • Effects of Antarctic Atmospheric Exposure Corrosion on Corrosion and Wear Properties of Laser-cladding Coatings
    CHEN Hao, CUI Zhongyu, CUI Hongzhi
    China Surface Engineering. 2026, 39(4): 227-237. https://doi.org/10.11933/CSE2026098
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    In recent years, with global warming, resource shortages, and environmental change, the exploration of polar resources, development of polar shipping, and protection of polar rights and interests have attracted increasing interest worldwide. Polar equipment materials must have excellent comprehensive properties, which include high strength and toughness, resistance to ice impact, high wear resistance, and high corrosion resistance at low temperatures. The existing design of low-temperature steel has encountered a bottleneck owing to complex operating environments. The high-performance coating achieved through the increasingly sophisticated laser cladding technology is anticipated to resolve the design dilemma between low-temperature toughness and high strength, as well as achieve high wear and corrosion resistance. In response to the requirements for the corrosion protection of marine steel and the application evaluation of stainless steel at low temperatures, this study used laser cladding technology to prepare coatings of austenitic stainless steel 316L and duplex stainless steel 2205 on the surface of FH690 steel, respectively. These stainless steel coatings were then subjected to a one-year exposure test in the atmospheric environment at Zhongshan Station in Antarctica. Under the protection of 316L and 2205 coatings, the corrosion rates of the steel matrix were 15.9 and 16.3 μm·a-1, respectively. Subsequently, the microstructure, microhardness, friction and wear behavior, electrochemical corrosion behavior, and stability of the samples in the polar low-temperature environment were analyzed. Notably, minor pitting corrosion was observed in the 316L coating, whereas selective corrosion occurred in the 2205 coating. The stainless steel coatings resist Cl- corrosion through a compact oxide film formed by readily passivating elements such as Cr and Mo. On the surface of the 316L coating, pitting marks emerged, whereas the 2205 coating exhibited a characteristic biphasic structure. Furthermore, both the 316L and 2205 coatings retained their respective stable structures: a single-phase austenite for 316L and a biphasic austenite-ferrite for 2205, both before and after exposure. The microhardness values of the 316L and 2205 coatings were maintained at about 280 and 390 HV0.2, respectively. Consequently, both coatings exhibited a stable friction coefficient of approximately 0.7. Notably, the 2205 coating demonstrated a reduced wear volume and lower wear rate than the 316L coating, which experienced more significant adhesive wear, with abrasive wear being the primary mechanism in the 2205 coating. The pitting breakdown potential of the 316L coating at the high potential region of the potentiodynamic polarization curve decreased by approximately 30 mV, accompanied by a doubling of the passivity current density. In contrast, the passivation interval of the 2205 coating remained stable at 1 300 mV, although the passivation current density increased from 2.455 to 4.177 μA·cm-2. After one year of exposure to the Antarctic atmosphere, the arc radius of the Nyquist plots for both 316L and 2205 coatings decreased, suggesting a decrease in the charge transfer resistance and stability of the passivated films. After exposure, the |Z| value in the Bode diagram for both coatings decreased, with the intermediate frequency region of the phase angle for both 316L and 2205 coatings shrinking, indicating a decline in passivation film quality. The fitting data from the double-layer model indicated that, despite a minor decrease in charge transfer resistance, the coating retained its ability to maintain a stable passivation state and a low corrosion rate. In summary, both coatings retained their stability in phase structure, hardness, and wear resistance after exposure to the Antarctic atmosphere. Despite experiencing minor surface corrosion that slightly reduced corrosion resistance, they exhibited an outstanding protective effect on the substrate. This paper provides a reference for evaluating the environmental adaptability of polar equipment materials and corrosion protection coating technology.
  • Effects of Ultrasonic Power on Refined Grain Distribution and Precipitated Phase Morphology of Laser Cladding
    YAO Zhehe, LIN Chenqi, ZHU Yi, CHEN Jian, CHI Yiming, YANG Huayong, YAO Jianhua
    China Surface Engineering. 2026, 39(4): 238-248. https://doi.org/10.11933/CSE2026329
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    High-end equipment in fields such as aerospace and nuclear power engineering operates under extreme conditions, and key components are prone to failures such as cracks, wear, and fatigue. The direct replacement of damaged parts is costly. Laser cladding technology, with its advantages of high metallurgical bonding strength and low heat-affected zone, has been widely used for the surface modification and repair of key components in high-end equipment. However, owing to the large temperature gradient during the laser-cladding solidification process, coarse columnar crystals and brittle precipitates are easily formed, resulting in anisotropy and strength reduction of the mechanical properties of the cladding layer, thereby weakening the service performance of the material. Ultrasonic-assisted laser cladding technology can effectively promote grain refinement, suppress the generation of harmful precipitates, and improve the quality of the cladding layer. However, the mechanism by which ultrasound power affects the distribution of fine equiaxed crystal structures and morphology of precipitated phases in the cladding layer have not been fully elucidated; further in-depth exploration is needed in related research. This study, based on ultrasound-assisted laser cladding experiments, systematically characterizes the microstructure of the cladding layer under different ultrasound power conditions, analyzing its influence on the distribution of fine grains and morphology of precipitated phases, and providing theoretical support for the evolution and regulation of grains during the laser cladding process. This study established an ultrasonic-assisted laser cladding experimental platform using stainless steel 316 L as the substrate and Inconel 718 alloy as the cladding powder (particle size range 53-150 μm). The experimental parameters were set as a spot diameter of 4 mm, laser power of 1.7 kW, scanning rate of 10 mm/s, powder feeding rate of 12.5 g/min, and ultrasonic power range of 0-5 kW. The influence of ultrasonic power on the depth of fusion and fusion line was studied by analyzing the macroscopic morphology of the cladding layer cross-section. Combined with the evolution law of the cross-sectional segregation zone, the macroscopic element segregation behavior of the cladding layer was explored. In terms of microstructure characterization, this study analyzed the morphology of dendrites at the bottom, middle, and top of the cladding layer, and examined the effects of ultrasound power on the morphology and distribution of columnar and equiaxed dendrites. Electron backscatter diffraction was used to characterize the inverse pole figure patterns, grain size distribution, average grain size, and transverse to longitudinal ratio of grains under different ultrasonic powers. The proportion change of small equiaxed grains in the cladding layer under high-intensity ultrasonic vibration was also quantified. Scanning electron microscopy was used to statistically analyze the proportion of the precipitated phase area in the cross-section of the cladding layer. The transformation of the precipitated phase morphology from continuous chain-like and network-like to dispersed granular and filamentous under ultrasound action were compared and analyzed. Combined with energy dispersive spectroscopy analysis, the spatial distribution characteristics of elements in the cladding layer were explored using line- and surface-scanning methods. The enrichment of strengthening elements Nb, Al, and Ti in different phases was analyzed through point scanning to support the influence mechanism of ultrasonic vibration on the microsegregation of interdendritic elements and the evolution of the precipitation phase morphology. Based on the Hall-Petch equation, the microhardness distribution cloud maps and average values of the cladding layer under different ultrasonic powers were measured to verify the existence of small equiaxed crystal regions and their improvement on the mechanical properties of the material. The results show that ultrasonic vibration can significantly refine the grain size of the cladding layer and suppress the macroscopic segregation of elements. With the increase in ultrasonic power, the formation of precipitated phases was further suppressed, and their morphology gradually changed from continuous chain-like and network-like to dispersed granular and filamentous. The average microhardness of the cladding layer had a positive correlation with the increase in ultrasonic power. When the ultrasonic power was increased to 3 kW, a small equiaxed crystal zone appeared at the top of the cladding layer. The area of this zone gradually expanded with increasing ultrasonic power. When the ultrasonic power reached 4 kW, the small equiaxed crystal zone almost covered the entire cladding layer. The average grain size decreased to 36 μm, a decrease of 85.2% compared to no ultrasonic conditions. The proportion of equiaxed crystals increased from 31.7% without ultrasound to 73.7%. The segregation zone phenomenon in the cladding layer basically disappeared, and the enrichment of interdendritic elements was significantly alleviated. The proportion of brittle precipitates decreased by 82.3% compared with the absence of ultrasound. The average microhardness of the cladding layer reached 235.0 HV0.3, an increase of 25.6% compared with the absence of ultrasound. This study analyzed the effects of ultrasound power on the distribution of fine-grained structures and the morphology of precipitated phases in the cladding layer. Research shows that under nonlinear effects, such as acoustic cavitation and acoustic flow generated by ultrasonic vibration, the microstructure of the laser cladding layer had a significant trend of refinement and equiaxement. With the increase in ultrasonic power, the refined equiaxed crystal region gradually expanded downward from the top of the cladding layer. At the same time, the morphology of the precipitated phase under ultrasonic action gradually changed from continuous chain-like and network-like to dispersed granular and filamentous. This study provides a reference for optimizing the laser cladding process and improving the microstructure and properties of the cladding layer.
  • Effect of Heat Treatment on the Tissue Properties of Laser Repair 7075 Aluminum Alloy
    HE Chen, LI Jiadong, WANG Junhao, ZHAO Yuhui, ZHAO Jibin, WANG Zhiguo, HE Zhenfeng
    China Surface Engineering. 2026, 39(4): 249-259. https://doi.org/10.11933/CSE2026151
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    High-strength 7075 aluminum alloy exhibits several disadvantages, including low laser absorption, high laser reflectivity, high thermal conductivity, and a strong tendency toward oxidation. Furthermore, it contains a significant number of low-boiling-point alloying elements and demonstrates a pronounced susceptibility to hot cracking. These factors lead to oxidation of the alloy, volatilization of low-boiling-point elements, pore formation, thermal cracking, warping deformation, and heat-affected zones during laser repair, thereby resulting in reduced mechanical properties of the repaired components. To enhance the mechanical properties in the repair region of 7075 aluminum alloys, laser melting deposition technology was employed in combination with (Ti + B4C) / AA7075 aluminum alloy composite powder. The repaired samples were subsequently treated using a sintering furnace (KSL-1700X) and a vacuum furnace (VBF-1200X). The strengthening of the repaired region was achieved through solution treatment followed by single-stage aging. The effects of various aging durations on the microstructure and mechanical properties of the samples were systematically investigated. The results indicated that solution treatment followed by single-stage aging significantly improved the compositional uniformity of both the repair zone and the heat-affected zone. The process facilitated the phase transition from TiAl3 to Ti3Al in the repair region, thereby enhancing the mechanical properties of the samples. Moreover, heat treatment effectively refined the grain structure in the heat-affected zone, which contributed to improved microhardness and tensile strength in that region. As the aging time increased from 0 h to 6 h, the average microhardness of the repair area was measured at 130.75, 136.93, 142.22, and 149.38 HV, respectively. Correspondingly, the average microhardness of the substrate was recorded as 96, 155.67, 156.88, and 164.28 HV. These findings demonstrated that increasing the aging time led to a continuous increase in hardness in both the repair zone and the substrate, with the substrate showing a significantly higher rate of hardness improvement compared to the repair area. This disparity is attributed to the fact that the 7075 aluminum alloy is a heat-treatable, high-strength aluminum alloy. Following solution treatment, alloying elements such as Zn and Mg, which were originally present in insoluble heterogeneous phases, were transformed into a supersaturated solid solution. During aging, fine η (MgZn2) precipitates formed within the substrate, resulting in increased hardness. In contrast, within the repair area, Zn and MgZn2 present in the aluminum-based repair powder were partially lost during laser repair, thereby diminishing the formation of the η (MgZn2) phase during aging. Additionally, the fine TiAl phase originally present in the repair region transformed into a dendritic Ti3Al phase during heat treatment. Although Ti3Al exhibits high strength, its grain refinement capability is weaker, thereby resulting in a smaller overall hardness increase in the repair area compared to the substrate. As aging time increased from 0 h to 6 h, the tensile strength of the samples improved progressively, with recorded values of 329.59, 372.17, 422.12, and 436.30 MPa, respectively. Compared to the non-heat-treated condition, this represents a 32.4% increase in tensile strength. However, the elongation decreased to 6.86%, 4.23%, 2.86%, and 2.27%, respectively, with the fracture mode characterized as brittle fracture. This behavior is attributed to the gradual transformation of TiAl3 into the stronger yet more brittle Ti3Al phase in the repair region during heat treatment, thereby increasing tensile strength while reducing toughness. With increasing aging time, the width of the grinding marks on the sample surface did not change significantly; however, the depth of the marks progressively decreased from approximately 25 µm (in the untreated condition) to 10 µm after 6 h of aging. This indicates that the dense distribution of the Ti3Al phase precipitated during heat treatment contributes to enhanced wear resistance of the aluminum matrix. After 1 h of solution treatment and 6 h of aging, the mechanical properties of the samples reached optimal levels. Under these conditions, the microhardness and tensile strength of the samples reached approximately 80% of those of forged 7075 aluminum alloy. Compared with the untreated condition, the microhardness of the substrate and repair area increased by 12.7% and 69.1%, respectively. The tensile strength increased by 32.4%, and the wear rate decreased from 10.4 × 10⁻5 mm3·N⁻1·m⁻1 to 4.63 × 10⁻5 mm3·N⁻1·m⁻1, reflecting significant improvement in wear resistance.
  • Microstructure and Wear Properties of ZrO2-reinforced Inconel 718 Alloy Fabricated by Laser-directed Energy Deposition
    CHENG Qing, ZHU Jian, WU Yongling, ZHENG Hongyu
    China Surface Engineering. 2026, 39(4): 260-270. https://doi.org/10.11933/CSE2026123
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    Advanced manufacturing industries demand metallic materials exhibiting both exceptional mechanical properties and wear resistance under extreme service conditions, such as elevated temperatures, corrosive environments, and heavy mechanical loads. Inconel 718, a nickel-based superalloy, has been extensively utilized in critical sectors, including aerospace, nuclear reactors, gas turbines, and other high-performance energy systems, to meet this requirement. This alloy is well recognized for its superior high-temperature strength, corrosion and oxidation resistances, and thermal stability. However, components fabricated via conventional techniques, such as casting or forging, frequently suffer from coarse and directionally solidified microstructures, segregation of alloying elements, and insufficient wear resistance. These limitations significantly restrict the potential of these alloys in demanding operational settings, prompting research on novel reinforcement strategies to overcome such deficiencies. In this context, laser-directed energy deposition (LDED), an advanced additive manufacturing technique that enables localized melting and solidification of metal powders, has been employed to fabricate Inconel 718-based composites reinforced with zirconia (ZrO2) ceramic particles. This study systematically investigated the influence of ZrO2 content—specifically 2.5wt.% and 5wt.%—on the microstructural characteristics, mechanical properties, and tribological performance of the resulting composites. The objective was to enhance the functionality of the material through grain refinement and particle-induced strengthening, thereby addressing the inherent shortcomings of conventionally processed Inconel 718. Inconel 718 powder and yttrium-stabilized ZrO2 powder (2.5wt.% and 5wt.%) were dried, mixed using a ball-mill machine, and fed into the co-axial powder feeder in the laser system. The deposition of the Inconel 718 alloy and composites was performed via a multichannel, multilayer approach. The key process parameters were as follows: laser power of 1 700-2 200 W, scanning speed of 10-20 mm / s, laser beam diameter of 4 mm, powder feeding rate of 1.2 r / min and scan overlap of 50%. A comprehensive suite of advanced characterization techniques was utilized in this study. X-ray diffraction was employed to identify the phase composition of the composite samples, and scanning electron microscopy and energy-dispersive spectroscopy revealed the microstructural morphology and elemental distribution. Electron backscatter diffraction was used to analyze the crystallographic orientation, grain size, and grain boundary characteristics. The mechanical performance was assessed through microhardness testing, and wear resistance was evaluated via dry sliding wear experiments under controlled loading and speed conditions. The incorporation of ZrO2 particles was found to significantly alter the solidification behavior during LDED. Ceramic particles served as effective nucleation sites and hindered the directional growth of columnar grains, thus promoting the development of equiaxed grains and more refined microstructure. The 5wt.% ZrO2 composite exhibited more uniform grain morphology and higher degree of grain refinement. The enhanced metallurgical bonding between the matrix and ceramic phases contributes to improved load transfer and microstructural stability. Mechanical testing results demonstrated an evident improvement in hardness, with the 5wt.% ZrO2 sample exhibiting an average microhardness of 456.3 HV--approximately 1.54 times higher than that of the unreinforced alloy. Tribological testing revealed a substantial enhancement in wear resistance. The wear rate was reduced by 60.5%, from 0.120 mm³·N-¹·mm-¹ in the pure alloy to 0.047 4 mm³·N-¹·mm-¹ in the reinforced composite. Moreover, the dominant wear mechanism transitioned from severe abrasive wear in the unmodified alloy to a combined mechanism of mild adhesion and oxidative wear in the reinforced samples. This indicated improved surface durability and thermal stability under frictional stress. The innovations of this study are two-fold. First, the effects of ZrO2 content on the microstructural refinement and wear behavior of Inconel 718 fabricated via LDED were systematically studied for the first time, offering new experimental evidence for ceramic reinforcement design. Second, the underlying mechanisms of grain morphology modification, hardness enhancement, and tribological transformation induced by ZrO2 particles were elucidated, providing valuable theoretical guidance for optimizing Ni-based superalloys for high-performance engineering applications. This study provides a foundation for the tailored design of advanced composites by using additive manufacturing and demonstrates the feasibility of ceramic-particle reinforcement in enhancing both structural and functional properties of high-temperature Ni-based alloys.
  • Preparation and Air Atmospheric Triboperformance of Magnetron Sputtered WSC Films
    GUO Yuting, LIU Zhonghao, LI Shang, LI Mao, DONG Xuanpu, LI Guona, WEN Feng, CAO Huatang
    China Surface Engineering. 2026, 39(4): 271-281. https://doi.org/10.11933/CSE2026082
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    Tungsten disulfide (WS2) solid lubricant materials are widely used in the aerospace and other industries; however, they exhibit inherent drawbacks such as poor mechanical properties and susceptibility to oxidation, which shorten their service life. To address these limitations under atmospheric conditions and enhance the mechanical performance and longevity of pure WS2, WS2-based nanocomposite films incorporated with carbon (WSC) were prepared by magnetron sputtering using WS2 and graphite targets at different sputtering powers. Microstructural and compositional analyses of the WS2-based films were conducted using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Furthermore, the mechanical properties and friction and wear characteristics were evaluated using nanoindentation, multifunctional tribometer, and white light interferometer. The results show that with an increase in the graphite target sputtering power, the C content in the WS2-based films continues to increase, the deposition rate increases and the ratio of S / W atoms increases as a whole. The surface roughness of the WS2-based films exhibits a notable decrease, resulting in a flatter and smoother texture. However, with an increase in the sputtering power, the surface morphology of the WS2-based composite films exhibits a cauliflower structure, indicating that the C content has no obvious effect on the surface structure of the films. In addition, all cross-sections are columnar, and the thickness of the film increases with the increase of the sputtering power of the target, reaching a maximum of 2.18 µm when the sputtering power is 400 W. XRD analysis reveals that a wide and weak convex peak with no other diffraction peaks can be observed in the carbon-doped composite films in the range of 2θ=30°-45°, showing a typical amorphous structure. In addition, nanoindentation testing reveals that the hardness and elastic modulus of the carbon-doped films are significantly higher than those of the pure WS2 films; however, these mechanical properties show minimal dependence on the sputtering power of the graphite target. Specifically, at a sputtering power of 400 W, the WS2-based film demonstrates peak hardness and elastic modulus, measured at 6.1 GPa and 80 GPa, respectively. Furthermore, the H / E to H3 / E2 increases significantly with the sputtering power of the graphite target and reaches its maximum at 400 W, mainly because the element is more evenly distributed in the film, which improves the density of the film, thus improving its wear resistance and plastic deformation resistance. In addition, the friction of coefficient and wear rate of WS2-based films exhibit a decreasing trend as the sputtering power increases, achieving their lowest values at 400 W, where the friction factor is measured at 0.18 and the wear rate is recorded at 3.12×10-6 mm3 / (N·m), which may be due to its high hardness, good densification, less abrasive chips and good wear resistance, and thus, the wear rate is effectively reduced. The frictional characteristics of the 400 W WS2-based films further analyzed through wear tracks via Raman spectroscopy reveal that under atmospheric conditions (approximately 50% relative humidity-50%RH), the wear marks of the WS2-based film are narrow, shallow, and smooth. The potential reason for this is that the surface of the WS2-based film is flat and dense during the tribological process, inhibiting the penetration of water molecules into the films. Additionally, amorphous carbon can passivate the active sites on the films, thereby diminishing the dissociation and adsorption of water molecules. This reduction in molecular interactions decreases the likelihood of chemical reactions. The enrichment of sp2 in amorphous carbon also enhances the tribological properties of the WSC films. This research provides a theoretical basis and technical guidance for the development of coatings with excellent wear resistance and friction-reduction performance.
  • Effects of Process and Structural Control on the Room Temperature Friction and Wear Properties of Plasma-sprayed AT13 / NiCrAl Composite Coatings
    XU Shiyao, ZHANG Xin, WANG Zihan, YU Rui, XIONG Yiming, ZHANG Kaicheng, WU Lintao
    China Surface Engineering. 2026, 39(4): 282-295. https://doi.org/10.11933/CSE2026079
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    The structure of an Al2O3-13wt.% TiO2(AT13) / NiCrAl composite coating was systematically tailored by improving the dual powder feed plasma spraying process. This study focused on optimizing both the process parameters and coating microstructure. The friction and wear properties of the coatings with different structural configurations were investigated under controlled conditions of a load of 50 N and sliding speed of 50 mm / s, using dry reciprocating friction tests. The results showed that, compared with a layer-by-layer spraying process, the simultaneous powder feed method significantly reduced the coating porosity from 3.42% to 3.10%, with the dispersed structure coating exhibiting the lowest porosity of 2.88%. Reduced porosity leads to improved wear resistance by minimizing localized stress concentrations, which could otherwise result in premature coating failure. Coatings with lower porosity exhibit enhanced structural integrity under wear conditions, thereby substantially increasing their abilities to resist friction and wear. Multilayer coatings prepared using layer-by-layer spraying often exhibit internal stress accumulation. During the friction and wear tests, microcracks within these coatings rapidly propagated, leading to a decrease in the bonding strength within the coating and an increase in the surface roughness, which thereby increased the friction coefficient. In contrast, the coatings prepared using the dual-powder feed-spraying process exhibited a more uniform internal stress distribution and thus significantly reduced the risk of crack formation and coating delamination, resulting in a lower friction coefficient and reduced porosity. The influence of the internal interface layers on the wear resistance of the composite coatings was examined. The introduction of such layers created a layered structure within the coating, which produces a “lamination effect”. This effect was critical to the improvement of the mechanical properties of the coating because the presence of more layers acted as a barrier to crack propagation. These findings suggested that increasing the number of layers in the coating significantly enhanced its resistance to wear. The multilayer coatings exhibited better durability under frictional loads because the layered structure impeded the spread of cracks, which thereby lowered the overall wear rate. The improvement in wear resistance observed in the multilayer coatings was particularly notable under high mechanical stress, and the wear mechanisms operating under these conditions were analyzed. Under high loads, the primary wear mechanism was adhesive wear, which was characterized by the formation of a bonding layer between the coating and counterface material during sliding. This bonding layer primarily consists of an oxide structure that acts as a lubricant and offers a degree of protection to the coatings. The bonding layer also facilitated metallurgical bonding with the coatings, which enhanced the adhesion strength, and thereby reduced the damage incurred during the wear process, thus leading to a lower wear rate and volume loss. However, under sustained frictional stress, the brittle nature of the bonding layer eventually led to its failure and caused extensive delamination and damage. In the later stages of wear, the protective effect of the bonding layer diminished. In contrast, the coatings produced using the dual-feed spraying process exhibited abrasive wear. Elevated temperatures during friction processes can induce thermal stress. Coatings with lower porosity and more uniform microstructure can better withstand the effects of thermal stress during sliding. The layered structure of the coating can partially impede the diffusion of heat and thereby reduce the possibilities of thermal damage to the coatings. This difference in wear mechanisms further highlights the influences of the coating structure and spraying processes on the tribological behavior of the coatings. The results of microstructural analyses via scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) showed that the simultaneous powder feeding process not only reduced porosity but also improved the stress distribution within coatings. The coatings produced by this process exhibited a more homogeneous distribution of ceramic and metallic phases. This homogeneity contributed to improved mechanical stability during wear, as the stress was distributed more evenly, thus reducing the formation and propagation of microcracks, which often precede failure in composite coatings that are subjected to high friction loads. A three-dimensional surface morphology analysis quantitatively assessed the influence of the coating structure on the wear rate. The results indicated that multilayer coatings exhibited significantly lower wear scar depths and widths than did the simpler structures. The multilayered coatings produced by the dual-feed process demonstrated superior wear resistance, as evidenced by their lower wear rates and reduced material losses during friction tests. The findings suggest that optimizing the spraying parameters combined with structural regulation is critical for enhancing the tribological performance of AT13/NiCrAl composite coatings. Moreover, optimizing the coating structure, particularly by reducing the porosity and incorporating internal interfaces, can substantially improve the wear resistance. The dual-feed spraying process shows promise for the fabrication of advanced composite coatings with enhanced mechanical properties and increased process efficiency. These coatings have potential applications in aerospace and automotive industries, where components are exposed to extreme wear conditions.
  • Influence of Interlayer Thicknesses on the Tribo-corrosion Behaviors of Cr3C2-NiCr / DLC Duplex Coatings
    HE Dongqing, LIANG Ruirui, FENG Zihan, SHANG Lunlin
    China Surface Engineering. 2026, 39(4): 296-311. https://doi.org/10.11933/CSE2026075
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    The working surfaces of the core components of machinery operating in marine environments, such as gears, bearings, valves, fastening devices, and drive chains, inevitably suffer from both corrosion and wear. Compared to damage caused by either corrosion or wear, the combined interaction of mechanics and electrochemistry significantly accelerate deterioration. The degree and rate of damage caused by this composite damage mode are significantly higher, thus limiting the long and reliable operation of marine equipment. An effective way to address these shortcomings is to use high-velocity oxygen-fuel (HVOF) technology to deposit a Cr3C2-NiCr cermet coating with high metallic toughness and ceramic hardness between the metal substrate and Diamond-like carbon (DLC) film to support the top layer of the DLC film. The overall performance of the coating was optimized by precisely controlling the thickness of the intermediate layer to satisfy the demands of different operating conditions. Scanning electron microscopy (SEM), a non-contact 3D surface profiler, a Raman spectrometer, and a tribometer in reciprocating motion mode, in combination with an electrochemical workstation, were used to investigate the corrosion behavior of Cr3C2-NiCr / DLC duplex coatings with different interlayer thicknesses in a 3.5wt. % NaCl solution. Additionally, tribo-corrosion behaviors were examined under open circuit potential (OCP), kinetic potential polarization, and cathodic protection conditions, and the synergistic relationship between corrosion and wear was analyzed, thus revealing tribo-corrosion mechanism. The results show that, because the corrosion resistance of the coatings under static corrosion conditions mainly depends on their structural densities, changes in the thickness of the intermediate layer have little effect on the electrochemical properties of the duplex coatings when the group distribution ratio remains unchanged. During the tribo-corrosion process, with an increase in the thickness of the intermediate layer, the material loss caused by the interaction between corrosion and wear gradually decreases. Specifically, at an intermediate layer thickness of 100 μm, the promotion of corrosion by friction is minimized (1.738%), and the duplex coatings show the most excellent corrosion and wear resistance performance. By comparing the results under static conditions with under dynamic potential polarization, it was found that all the duplex coatings exhibited more negative corrosion potential (Ecorr) values and higher corrosion current densities (icorr) under dynamic potential polarization. Compared to the duplex coatings under dynamic polarization conditions, those with an applied cathodic protection potential of OCP-0.8 V had narrower and shallower wear marks; however, pitting was still observed. Analysis of the microstructure within the wear marks of the duplex coatings under dynamic polarization and cathodic protection conditions revealed that corrosion played a dominant role when the thickness of the intermediate layer was small, whereas wear gradually dominated as the thickness of the intermediate layer increased. In the overall tribo-corrosion assessment of the Cr3C2-NiCr / DLC duplex coatings, both pure and friction-promoted corrosion resulted in a small percentage of material loss, indicating that wear is the main cause of material loss in the tribo-corrosion process. Finite element analysis software was used to simulate the equivalent stresses and shear stresses of the duplex coatings with intermediate layer thicknesses of 25 and 100 μm. The results confirmed that increasing the thickness of the intermediate layer increases the contact stresses of the DLC films, promoting the graphitization of the top layer of the DLC film. This transformation effectively both the friction coefficient and wear rate of the duplex coatings, thereby optimizing the overall structure of the coatings. This research is expected to promote the composite application of cermet coatings and carbon-based films in marine environments and provide new ideas and approaches for the development of high-performance marine tribo-corrosion resistant HVOF / PVD duplex protection systems.
  • Effect of CaF2 Content on Friction and Wear Properties of NiCrAlY Coating at High Temperature
    LIU Hongge, JING Jiannong, CUI Xiangzhong, LI Jing, CUI Xiufang, JIN Guo, ZUO Ping
    China Surface Engineering. 2026, 39(4): 312-321. https://doi.org/10.11933/CSE2026192
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    With the continuous increase in the thrust-to-weight ratio of next-generation aero-engines, more stringent requirements are being placed on the service temperature of internal friction pairs. Consequently, the development of advanced high-temperature lubricating and wear-resistant coatings has become critical for ensuring the reliable operation of key components under extreme conditions. This demand has intensified the need for solid lubricating and wear-resistant coatings capable of maintaining stability at elevated temperatures. Among existing materials, NiCrAlY coatings are widely employed as thermal protective layers owing to their excellent high-temperature oxidation resistance and favorable mechanical properties. However, their inherent friction and wear performance at elevated temperatures remains insufficient and requires improvement. In this context, calcium fluoride (CaF2) has emerged as a promising high-temperature lubricant, owing to its broad operational temperature range and cost-effectiveness. This study aims to systematically investigate the influence of CaF2 content on the high-temperature friction and wear behavior of NiCrAlY coatings, thereby providing a theoretical basis for optimizing high-temperature lubricating coatings for aero-engine applications. Three types of coatings were prepared using APS-3 000 atmospheric plasma spraying equipment: a pure NiCrAlY coating (Group O, control), NiCrAlY coating containing 6 wt.% CaF2 (Group A), and NiCrAlY coating containing 12 wt.% CaF2 (Group B). The substrate material was GH5188 superalloy, which was subjected to sandblasting prior to deposition to enhance coating adhesion. The spraying process was conducted under strictly controlled parameters: primary gas flow of 45 L / min, secondary gas flow of 8 L / min, voltage of 550 V, current of 70 A, and power of 36 kW. The powder feeding rate was maintained at 30 g / min, resulting in a coating thickness of approximately 300-320 μm. Friction and wear tests were conducted over a temperature range from room temperature to 800 ℃ using a pin-on-disk tribometer in accordance with the CSTM standard for high-temperature wear testing. The counterpart material was an IC21 alloy ball (φ10 mm) with a load of 10 N, rotation speed of 30 r / min, friction radius of 5 mm, and test duration of 30 min. Microstructural characterization of the coatings was performed via scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS), and phase analysis was conducted using X-ray diffraction (XRD). Mechanical properties, including hardness and bonding strength, were measured using a Vickers hardness tester and tensile testing machine, respectively. The results revealed distinct temperature-dependent friction and wear behaviors. In the low-temperature range (≤400 ℃), both the friction coefficient and wear rate of Groups A and B initially increased with temperature, peaking at 400 ℃, before subsequently decreasing. Specifically, Group A exhibited a maximum wear rate of 8.07×10-4 mm³ / (N·m), whereas Group B reached 9.59×10-4 mm³ / (N·m) at 400 ℃, primarily owing to severe abrasive wear and adhesion effects. At 200 ℃, prominent plowing grooves and wear debris were observed on the wear tracks, with partial debris compacted into island-like friction layers. In the high-temperature range (≥600 ℃), the friction and wear performance improved significantly. At 600 ℃, CaF2 underwent a ductile-brittle transition (softening above 500 ℃) and began to provide effective lubrication, thereby reducing friction. By 800 ℃, XRD analysis confirmed the complete conversion of surface CaF2 into CaCrO4, a high-performance solid lubricant at elevated temperatures. This transformation resulted in significantly reduced friction coefficients of 0.25 for Group A and 0.28 for Group B, in conjunction with corresponding wear rates of 1.13×10-4 mm³ / (N·m) and 1.7×10-4 mm³ / (N·m), respectively. EDS results revealed that the wear tracks at 800 ℃ were covered with oxide films enriched in O (27%) and Ca (20%), forming a protective layer. Mechanical property measurements further indicated that increasing CaF2 content led to a reduction in coating hardness (290.3 HV0.5 for Group A vs. 254.2 HV0.5 for Group B) and bonding strength (39.4 MPa for Group A vs. 30 MPa for Group B). In conclusion, the incorporation of CaF2 effectively enhanced the high-temperature lubricating performance of NiCrAlY coatings, with the formation of CaCrO4 at 800 ℃ identified as the key mechanism underlying friction reduction. Nevertheless, the addition of CaF2 slightly compromised low-temperature performance owing to increased coating brittleness. These findings not only provide viable options for the development of high-temperature lubricating and wear-resistant coatings but also offer valuable data to guide the compositional design of next-generation coatings for aero-engine applications.
  • Effect of Aging Treatment on Surface Pitting Corrosion Behavior of Solid Solution / as-rolled UNS S32304 Duplex Stainless Steel
    HE Fushan, CHEN Junlin, ZHENG Kaikui, LIANG Yiming, XIANG Hongliang, HU Wenfu
    China Surface Engineering. 2026, 39(4): 322-331. https://doi.org/10.11933/CSE2026125
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    Duplex stainless steel (DSS), characterized by a microstructure comprising approximately equal proportions of body-centered cubic ferrite (α) and face-centered cubic austenite (γ), exhibits a synergistic combination of enhanced mechanical properties and corrosion resistance, rendering it suitable for diverse applications in chemical, marine, and other critical industrial sectors. Industrially, DSS is broadly classified into solution-treated and as-rolled conditions. However, even within the same alloy grade, variations in processing history, particularly heat treatment methodologies, can lead to significant differences in microstructure and resultant mechanical and electrochemical properties. The aging-induced precipitation behavior in DSS is a critical factor influencing its corrosion resistance. This study investigates the microstructural evolution and pitting corrosion behavior of UNS S32304 DSS in both the solution-treated (S2304) and as-rolled (R2304) states following isothermal aging at 700 ℃ for durations of 0.5, 1, 2, 4, 8, 16, 24 and 32 h. Microstructural characterization and pitting corrosion morphology were assessed using optical microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The pitting corrosion resistance in a 3.5% NaCl solution was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization results revealed that for both S2304 and R2304, increasing aging time at 700 ℃ led to a progressive decrease in the self-corrosion potential and pitting potential, accompanied by an increase in corrosion current density. These findings indicate that the pitting corrosion resistance of S2304 and R2304 progressively weakened with prolonged aging. Under the same aging time, R2304 exhibited a lower self-corrosion potential and pitting termination potential as well as a higher corrosion current density than S2304, demonstrating that R2304 is more susceptible to chloride ion corrosion than S2304. EIS results indicated that both S2304 and R2304 displayed a single capacitive arc at each aging time. As the aging time increases, the radius of the capacitive arc for both alloys gradually decreases. The EIS fitting results revealed that the double-layer capacitance of the electrode surface for S2304 and R2304 increased with aging time, whereas the charge-transfer resistance of the passive film decreased. Thus, the stability of the passive films on S2304 and R2304 gradually declined over time, leading to a weakened pitting resistance and an increased tendency to form stable pitting cavities. For the same aging time, R2304 exhibited a smaller capacitive arc radius and lower charge-transfer resistance than S2304, along with a higher double-layer capacitance on the electrode surface. Therefore, the passive film stability of R2304 was inferior to that of S2304 under identical aging conditions, resulting in a relatively poor pitting resistance. Pitting morphology analysis indicated preferential nucleation of pits within the α-phase for both S2304 and R2304. With increasing aging duration, micro-pores within the ferrite phase evolved into larger pitting cavities. In R2304 aged for shorter durations (0.5, 1, and 2 h), a high density of fine pitting pores was observed within the α-phase, a feature absent in S2304 under identical aging conditions. Following 4 h of aging, fine pitting pores initiated at the α / γ phase boundaries in both S2304 and R2304, with their accumulation intensifying with longer aging times. This phenomenon is attributed to the precipitation of a chromium-depleted secondary γ2 phase at the α / γ interfaces, thereby promoting the nucleation and subsequent growth of pitting pores along these boundaries over time. In conclusion, this systematic investigation elucidates the influence of aging time on the microstructure and pitting corrosion resistance of solution-treated and as-rolled UNS S32304 DSS, clarifying the temporal evolution and underlying mechanisms. This study characterized the precipitation of secondary phases as a function of aging time, providing fundamental insights for optimizing the practical application of UNS S32304 DSS in corrosive environments.
  • Effects of Sliding Velocity-induced FeS / Cu Interface Bonding on the Tribological Properties of Pb-free FeS / Cu-Bi Composites
    LIU Cong, WANG Haoping, HE Chao, ZHANG Guotao, YIN Yanguo
    China Surface Engineering. 2026, 39(4): 332-343. https://doi.org/10.11933/CSE2026094
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    Pb is a soft metal with a low melting point and can impart favorable antifriction properties to Cu-based sliding bearing materials; however, it is toxic and harmful to human health and the environment. Nevertheless, the development of Pb-free materials has considerably progressed. Bi as a substitute for Pb in Cu matrices can improve the tribological properties of Cu-based composites; however, the inherent brittleness of Bi and its network-like distribution in Cu alloy matrices lead to the formation of large sheet-like wear debris along the Bi-rich regions during sliding friction, considerably reducing wear resistance. The incorporation of the hexagonal-layered solid lubricant FeS, which has a low shear strength, into Cu-Bi materials enables the preparation of Pb-free self-lubricating FeS / Cu-Bi materials. FeS can prevent cracks from propagating along a continuous Bi network, thus inhibiting the formation of matrix regions where Bi fragments may peel off. The FeS and Bi phases play an important role in synergistic lubrication, strengthening interfaces and mitigating crack propagation. However, FeS exhibits poor wettability with the Cu matrix, and introducing FeS lubricant phases into Cu matrices can disrupt the continuity of the metal matrices, considerably reducing the mechanical properties and reliability and limiting the effective utilization of the tribological and mechanical properties of composite materials. The interfacial bonding strength of heterogeneous phases plays a crucial role in self-lubricating composite materials containing solid lubricating phases. Therefore, controlling the interfacial properties between the phases in composite materials remains a considerable challenge in enhancing tribological performance and achieving efficient lubrication. The bonding strength between FeS and a Cu interface critically influences the tribological properties of Pb-free Cu-based composites. Therefore, tailoring the interfacial properties to match the service conditions is of great importance for the effective utilization of the frictional and wear properties of Pb-free FeS / Cu-Bi materials. The effect of sliding velocity-induced FeS / Cu interface bonding on the tribological properties of Pb-free FeS / Cu-Bi materials was investigated for two types of Pb-free FeS / Cu-Bi composites prepared using a powder metallurgy technology. The composites were composed of FeS or Ni-plated FeS particles, and FeS modification was achieved using electroless nickel plating technology. Both composites were subjected to sliding friction tests on a ring block friction testing machine, and self-lubricating material ring block sliding friction finite element models were established for the weak and strong interfacial bonds of the heterogeneous FeS / Cu phases. The internal stress field of the material, interface damage between the FeS particles and Cu alloy, and FeS migration were accurately simulated during the friction process. The simulations overcame the limitations of traditional experimental methods that restricted the observation of solid lubricant precipitation inside materials. Meanwhile, the deformation mechanism of the matrix and lubricating phase particles was revealed from a microscopic perspective, and the effect and mechanism of sliding velocity-induced FeS / Cu interface bonding on the antifriction and wear resistance of Pb-free FeS / Cu-Bi materials were elucidated. The results demonstrated that enhancing the FeS / Cu interface bonding considerably improved the antifriction and wear resistant properties of the FeS / Cu-Bi materials. The friction coefficient and wear rate of the FeS / Cu-Bi materials with weak and strong interface bonding decreased and then increased with increasing sliding speed, mainly because of the close relationship between the adhesion of FeS at the friction interface, bonding strength at the FeS / Cu interface, and sliding speed of the material. In materials with weak interfacial bonds between FeS and Cu, FeS particles precipitated as large particles resembling “intergranular fracture”, that restricted their adhesion at the friction interface. Following the enhancement of FeS / Cu interfacial bonding, FeS particles in the material precipitated as fine particles resembling “transgranular fracture”. These fine fragments containing solid lubricants completely filled the worn surface. At moderate sliding speeds, the precipitated fine FeS filled the friction interface and adhered to Bi to form a good friction film. The research aims to provide a theoretical basis and practical guidance on the influence and mechanism of lubricant-particle interface strengthening on the tribological properties of materials.
  • Effects of Different Strengthening Treatments on Wear Performance of ZL109 Alloy with Similar Hardness Level
    XING Luchao, ZHANG Chunxia, SUN Weitao, LIU Xiaoliang, ZHANG Jian, WANG Bin
    China Surface Engineering. 2026, 39(4): 344-353. https://doi.org/10.11933/CSE2026143
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    ZL109 alloy, a critical material used in piston fabrication, faces significant challenges regarding wear life under increasingly severe operating conditionsI edited this sentence for conciseness. Please check.. Enhancing material hardness through various strengthening methods is a primary approach to improving wear resistance; however, under high-temperature and high-pressure environments, material performance inevitably deteriorates. To date, the resistance to degradation and the underlying mechanisms associated with different strengthening strategies require further systematic investigation. In this study, three distinct strengthening methods—grain refinement, strain hardening, and heat treatment—were applied to ZL109 alloy, with all strengthened samples adjusted to exhibit the same hardness level. Subsequently, wear tests were performed using a reciprocating ball-on-disk tribometer under varying Since “varying” is already used here, there is no need to use “high-temperature/load” further down the sentence.temperatures (room temperature and 250 ℃) and loads (5 N and 15 N). After the wear tests, the morphologies of the worn surfaces were analyzed to identify the dominant wear mechanisms. Additionally, the microstructural evolution of the surface during friction was characterized to elucidate the mechanisms underlying performance degradation. The chemical compositions of the worn surfaces were also examined to assess the role of mechano-chemical reactions in high-temperature wear resistance. Furthermore, friction coefficients were recorded for all samples under the various testing conditions. The results indicate that all three strengthening methods improve the wear resistance of ZL109 alloy, regardless of the operating conditions. Under ambient temperature and low load, hardness was found to be the primary factor governing wear behavior, resulting in all strengthened samples exhibiting a similar wear rate of approximately 1.3 × 10-5 mm3 / N·m. In this regime, abrasive wear was identified as the dominant mechanism. However, with increasing temperature and load, the prevailing wear mechanism gradually shifted from abrasive wear to adhesive wear, leading to more severe material loss. This transition was particularly pronounced in as-cast samples. The increased surface deformation and higher viscoelasticity under tribological loading promoted the formation of adhesive junctions. Under ambient temperature and high load, wear performance varied among the strengthened samples. The grain-refined samples demonstrated superior wear resistance compared to the other two, primarily due to the formation of larger wear debris at the tribological interface, which enhanced third-body abrasive wear behavior. In the case of strain-hardened samples, the generation of larger debris was attributed to pre-existing defects, such as fractured Si phases, which facilitated crack initiation. For heat-treated samples, debris formation was associated with peeling of the Mg₂Si phase under severe stress concentration during reciprocating friction. Under high-temperature conditions, the wear resistance of all strengthened samples declined, although the heat-treated samples exhibited the best overall wear performance. This improvement was attributed to the precipitates' pinning effect on dislocation movement. In contrast, the reduced wear resistance observed in grain-refined samples at elevated temperatures resulted from grain coarsening, which diminished the effectiveness of grain boundary strengthening. Please check if the changes made here retain your intended meaning.For strain-hardened samples, dynamic recovery and recrystallization were the principal causes of performance degradation at high temperatures. In addition to mechanical wear, oxidative wear was observed at elevated temperatures and significantly contributed to the accelerated wear process. However, the extent of oxidative wear was strongly dependent on the severity of mechanical wear. Mechanical damage compromised the surface integrity, providing oxygen with easier access to subsurface regions, thereby facilitating oxidative reactions. In summary, the more severe the mechanical wear, the more pronounced the oxidative wear. The findings of this study offer direct experimental evidence and theoretical insights that can support the improvement of piston service life under extreme operating conditions.
  • Magnetic Abrasive Finishing Process under Electromagnetic-permanent Magnet Double Alternating Combined Magnetic Field
    DING Yunlong, MA Long, YAN Yuhang, HAN Bing, CHEN Yan
    China Surface Engineering. 2026, 39(4): 354-365. https://doi.org/10.11933/CSE2026193
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    A combined alternating magnetic field system was developed to overcome the limitations of traditional magnetic particle grinding processes, such as single abrasive grinding trajectories and inefficient cutting-edge recycling, which result in low processing efficiency. This system integrates permanent-magnet alternating fields with alternating electromagnetic fields. During operation, the permanent magnet and electromagnet alternate cyclically; when one is magnetized, the other is not, ensuring consistent magnetic induction intensity in the processing area. This cyclical switching promotes continuous tumbling and renewal of abrasives, thereby enhancing processing efficiency. Simulations were conducted to model various states within the combined alternating magnetic field, achieving cyclic switching between four distinct magnetic field states. Due to the complex magnetic configuration, magnetic abrasives inside the pipe fitting dynamically alternate between aggregating and shedding on one side before reaggregating on the opposite side. This study explores the processing effects of combined alternating magnetic field particle grinding and examines how the combined alternating frequency influences processing outcomes. A grinding time of 15 min was selected for the experiments. Using a three-factor, three-level response surface methodology, an optimization experiment was designed with voltage amplitude, frequency, and abrasive mesh size as test variables. A linear regression model relating surface roughness (response variable) to the independent variables was fitted using specialized software. Analysis of the response surface data revealed the relative influence of the test factors on the inner surface roughness of the brass tubes, ranked as follows: voltage amplitude > abrasive mesh size > frequency. Comparative tests were performed under identical conditions, grinding brass tubes using both permanent and combined alternating magnetic fields. The inner surface profile, morphology, and roughness of the pipe fittings were characterized using a white light interferometer, an ultra-deep field 3D electron microscope, and a horizontal surface roughness measuring instrument. After grinding with the combined alternating magnetic field, the surface roughness improved to Ra 0.059 μm, compared to Ra 0.102 μm after grinding with the permanent magnetic field. The optimal process parameters identified via the response surface method were a voltage amplitude of 5.2 V, a frequency of 4 Hz, and an abrasive mesh size of 80#. Under these conditions, the inner surface roughness of the brass tube decreased significantly, from Ra 0.594 μm to Ra 0.044 μm. Morphological analysis showed that major defects present on the original surface were completely eliminated, revealing clear and uniform textures on the processed surface. Furthermore, the surface contour height was reduced from 2.5 μm to less than 1 μm, achieving a stable and smooth profile. These findings demonstrate the effectiveness of the response surface methodology in optimizing grinding process parameters. Experimental results confirm that, under sufficient magnetic induction intensity, the combined alternating magnetic field particle grinding process enables abrasives to follow more complex trajectories within the pipe fitting. This significantly improves the utilization of abrasive cutting edges, enhances processing efficiency, and markedly elevates the inner surface quality of the pipe fittings.
  • Analysis and Predictive Modeling of Material Removal Profile Evolution in Magnetic Abrasive Finishing of Ti-6Al-4V Planar Surfaces
    ZHAN Jiawei, YING Jun, ZHANG Peng, DING Yunlong, ZHANG Yue, HAN Bing
    China Surface Engineering. 2026, 39(4): 366-378. https://doi.org/10.11933/CSE2026135
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    Magnetic abrasive finishing is a flexible processing technology that governs the material removal of magnetic abrasives from the surfaces of components. This enables the attainment of a superior surface quality with minimal surface material removal. The flexible contact nature of magnetic abrasive finishing has prominent advantages in the precision manufacturing of aerospace parts. Nevertheless, the semi-free state of the flexible “abrasive brush” composed of magnetic abrasives also presents issues such as an indistinct processing mechanism and the incapability of precisely quantifying the material removal. Consequently, this study presents a material removal model for magnetic abrasive finishing, which can predict the material removal quantity and surface contours of parts following magnetic abrasive finishing. First, the magnetic induction intensity of the magnetic pole and the energy accumulation outcomes during processing are analyzed through finite element and discrete element simulations. The magnetic abrasives converge towards the outer side of the circular magnetic pole owing to the influence of the magnetic induction intensity and rotational speed of the magnetic pole. The effective grinding area of the magnetic pole is the outer side, and the formation mechanism of the surface contour of the part after magnetic abrasive finishing is clarified. A constant pressure single-point test that solely modifies the grinding force is devised by analyzing the effective grinding area on the magnetic pole. To ensure the accuracy of the test results, three sets of tests are designed for each test condition in the constant-pressure single-point test. The material removal quantity after grinding is measured using a white-light interferometer, and the average value is regarded as the final test result. Based on the constant-pressure single-point test results of magnetic abrasive finishing, a pressure distribution coefficient model for the circular magnetic pole in magnetic abrasive finishing is proposed to obtain the distribution of the grinding force and material removal coefficient. By analyzing the grinding speed of each point on the magnetic pole during the magnetic abrasive finishing process, calculating the effective grinding force distribution, and analyzing the accumulation of material removal in the processing area, an analytical model of the abrasive motion for the circular magnetic pole in the magnetic abrasive finishing plane is established. Based on this model, a material removal model for magnetic abrasive finishing based on Preston's equation is proposed to predict the material removal quantity and surface contours of the parts after processing. A three-axis magnetic abrasive finishing constant-pressure processing platform capable of measuring the grinding force is constructed. Additionally, based on the three test factors of grinding force, rotational speed of the magnetic pole, and processing time that influence magnetic abrasive finishing, a magnetic abrasive finishing and polishing test for the Ti-6Al-4V plane is designed. The changes in the surface contour of the part during processing are measured using a white-light interferometer, and the evolution of the surface contour of the part during magnetic abrasive finishing is analyzed. The measured material removal quantity in the actual processing and the material removal quantity predicted by the material removal model are compared. The surface contour of the part after grinding predicted by the material removal model and the actual measured surface contour are compared to verify the accuracy of the proposed model. The test results indicate that the average error between the proposed material removal model and the actual processing measurement values is 8.39%. The predicted results align well with the actual processing results. Compared with the average error of the existing material removal models for magnetic abrasive finishing, it falls within an acceptable range and can provide a theoretical foundation for an in-depth study of magnetic abrasive finishing.
  • Influence of Grinding Wheel Dressing on Surface Integrity of HT250
    ZHOU Jinggang, ZHANG Ning, HUANG Dong, LIU Liangbao, LI Xun
    China Surface Engineering. 2026, 39(4): 379-387. https://doi.org/10.11933/CSE2026194
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    Cast iron HT250 is considered an ideal material for manufacturing guideways due to its excellent wear resistance and relatively high mechanical strength, which meet the requirements for high precision and stability. Grinding is one of the most effective finishing techniques for producing high-quality machine tool guideway surfaces. The dressing condition of the grinding wheel is the most direct and critical factor influencing both the surface quality of the workpiece and the grinding performance of the wheel. Currently, studies on the wear resistance of ground guideway surfaces and its influencing factors remain limited in scope and lack systematic integration. This study investigates the impact of surface integrity and grinding wheel dressing parameters on ground surface the wear resistance of ground surfaces to support the development of ultra-precision equipment. By appropriately selecting dressing parameters, the surface roughness, surface microhardness, and plastic deformation layer of the ground workpiece can be effectively controlled. This also helps identify the optimal grinding stage at which the grinding wheel performs best. To explore trends in surface integrity and their underlying mechanisms, surface integrity indicators were measured while grinding HT250 specimens using varied dressing parameters of a SiC grinding wheel. Correlations between dressing parameters and grinding performance were established, allowing for the evaluation of their impact on grinding wheel life. The results indicate that, within the range of experimental conditions, the surface roughness of the ground specimens increased with the single-pass dressing depth h, which ranged from 10 μm to 30 μm. The greatest plastic deformation and maximum microhardness were observed at h = 20 μm. Furthermore, as the dressing feed rate and dresser apex angle increased, the surface roughness first decreased and then increased, while the surface microhardness first increased and then decreased. The hightest surface microhardness was achieved when the dressing feed rate was vp = 10 mm / min and the dresser apex angle was α = 100°. Additionally, when the dressing parameters were set to α = 100°, vw = 10 mm / min, and h = 20 μm, the ground surface exhibited clear and uniform grinding textures without pits, and the grinding wheel achieved a service life of T = 20 min, an improvement of approximately 50% compared to other dressing conditions. Under these parameters, the grinding surface roughness and microhardness during the rapid wear stage of the wheel were also unstable. Moreover, when the grinding time exceeded the wheel’s service life, thermal damage such as surface burns occurred on the workpiece. During the stable wear phase of the grinding wheel (2 min ≤ T ≤ 20 min), the surface microhardness of the ground specimens consistently remained above 300 HV, and the residual stress of the ground surface was compressive. Under these conditions, the wear resistance of the ground HT250 surface significantly improved, characterized by a higher microhardness and more pronounced plastic deformation, while maintaining the required surface roughness. Through a systematic study of the effects of spherical diamond dressing parameters on the surface integrity of cast iron HT250 and the grinding performance of the wheel, an optimization model for dressing parameters was developed. This provides a valuable reference for precision grinding of guideways in high-end machine tool equipment.
  • Simulation on Fatigue Life of Cylinder Block Extrusion Enhanced Finishing Treatment
    ZHANG Baoqing, ZHAO Shuai, SUN Yanbo, ZHANG Chaoyi, SUN Lihua
    China Surface Engineering. 2026, 39(4): 388-397. https://doi.org/10.11933/CSE2026195
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    After mechanical extrusion, the inner walls of cylindrical bodies undergo irregular deformation. If a cylindrical body with such deformation is used directly without treatment, it becomes more prone to cracking during operation, resulting in leakage of the cylinder body and potential casualties. Therefore, it is necessary to finish the inner wall of the cylinder block after mechanical extrusion. However, the influence of the finishing allowance on the fatigue life of the cylinder block remains unclear. It is of great significance to explore the influence of the finishing allowance on the fatigue life of a cylinder block for the design and processing of high-pressure cylinder blocks. Due to the limitations of long-cycle fatigue tests, poor repeatability, and unclear internal failure phenomena, this study combines the Shigley approximation method with fatigue simulation to estimate and analyze the fatigue life of the cylinder block after finishing. A finite element model of the cylinder block and mandrel was developed using ABAQUS finite element simulation software. Based on a bilinear strengthening material model that accounts for material strain hardening and the Bauschinger effect, the material removal process was simulated by integrating element birth and death techniques with multiple analysis steps. Taking the cylinder body after finishing as the research object, the material removal of different finishing allowances was carried out on the cylinder body, and the corresponding stress cloud diagram of the cylinder body after different finishing allowances was obtained. Based on these stress cloud diagrams, fatigue life simulation of the cylinder block after finishing was performed using fatigue analysis software, analyzing the influence of finishing allowance on fatigue life. An error analysis between the theoretical and simulation results were conducted to verify the feasibility of using the finite element method for fatigue life prediction. The results show that the weakest area of the cylinder block after finishing is located at the elastic-plastic interface. Material removal caused this interface to shift toward the outer wall of the cylinder block, with the largest offset observed when the finishing allowance was 2 mm. After material removal, residual stress in the cylinder body was released, which reduced the fatigue life of the cylinder body. With increasing finishing allowance, the fatigue life of the cylinder body continuously declined. A negative linear relationship was observed between the finishing allowance and the fatigue life of the cylinder body. Among the various finishing allowances examined, the cylinder block with a 0.5 mm finishing allowance exhibited the highest fatigue life. In contrast, when the finishing allowance was 2 mm, the fatigue life of the cylinder block was significantly reduced and was much lower than that of the untreated cylinder. Therefore, it can be considered that the simulation results lack reference value when the finishing allowance exceeds 2 mm. It is recommended to control the finishing allowance within 1.5 mm for industrial applications. In this study, the Shigley approximation method was used to estimate the fatigue life of the cylinder after finishing, and the error between the theory and the simulation results was compared and analyzed, which confirmed the feasibility of using finite element simulation to predict the fatigue life. Through the combination of theory and simulation, the influence is analyzed comprehensively, which provides a theoretical basis for the design and processing of high-pressure cylinder block.
  • Numerical Simulation of Film Forming Characteristics of Ring Plane Spraying
    WANG Yihao, ZENG Yonglong, HU Jinglei, DAN Binbin, FENG Pengyun, DU Liping
    China Surface Engineering. 2026, 39(4): 398-408. https://doi.org/10.11933/CSE2026144
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    Grain-oriented silicon steel, also known as oriented electrical steel, is a critical soft magnetic alloy widely used in the manufacturing of large- and medium-sized transformers as well as large motors. Following extensive technical analysis and practical process validation, a specialized MgO inhibitor layer was applied to the end face of the steel coil prior to high-temperature annealing in a ring furnace. This layer effectively suppresses the coarsening of edge grains, thereby enhancing the material plasticity at the edges of the oriented silicon steel and significantly reducing the incidence of edge cracks. After coating the coil’s end face with MgO, the interlayer isolation effect under high-temperature conditions was improved, which in turn effectively enhanced interlayer bonding after annealing and increased the yield during the tensile annealing process. To investigate the film-forming characteristics at different spraying positions on the annular end face of the steel coil, the Euler-Lagrange method was employed to develop an annular plane flow field model. This approach comprehensively analyzed the interaction between the gas and liquid phases during spraying and their influence on the film formation characteristics. The diffusion and film-forming zones during spraying were studied in detail through the construction of spray atomization flow field and spray liquid film models. By examining the evolving features of the gas-phase flow field alongside the shape and thickness distribution of the liquid film in various regions, differences in gas-phase flow characteristics and coating thickness deposition patterns at different spraying positions on the annular end face were compared and analyzed. Through this multidimensional analysis, the film-forming characteristics of the annular plane boundary area during spraying and their impact on spraying quality are systematically revealed. This provides a critical theoretical foundation and reference for optimizing spraying process design, as well as improving coating uniformity and adhesion. The results indicate that, regarding flow field characteristics in the diffusion zone, the gas velocity distributions for the three different spraying positions across the long- and short-axis sections are essentially similar. The long-axis section exhibits a fan-shaped distribution, whereas the short-axis section presents a jet-shaped distribution. Within the film-forming area, due to the influence of the sprayed surface geometry, significant differences in gas velocity distribution exist between the long- and short-axis sections at the three spraying positions. Regarding coating characteristics, the liquid film at the middle diameter position is elliptical, while the liquid films at the inner and outer diameter positions are semi-elliptical. Compared to the middle diameter position, the liquid films at the inner and outer diameters display diffusion along the boundaries. The film thickness variation along the long-axis direction at all three spraying positions is single-peaked, whereas the thickness variation along the short-axis direction is single-peaked at the middle diameter position and double-peaked at the inner and outer diameters. Based on these findings, the film-forming characteristics exhibit significant spatial variation depending on the spraying position on the ring plane. This variation is primarily governed by the coupling effects of multiphase fluid flow during the spraying process. A systematic investigation of these differences has elucidated the underlying mechanisms driving film formation in annular plane spraying. The research outcomes provide a vital theoretical basis for further exploration of multiphase flow coupling and liquid film deposition dynamics during spraying, holding important implications for optimizing spraying processes.
  • Preparation of High-quality Patterned Copper Layer by Ultra-high-speed Direct Current Electrodeposition
    LI Tianxiang, YUAN Hao, CAI Wentong, PENG Yang, WANG Qing, CHEN Mingxiang
    China Surface Engineering. 2026, 39(4): 409-421. https://doi.org/10.11933/CSE2026162
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    In high-power device packaging, patterned copper coatings are essential for redistribution layers and the formation of functional microstructures. The patterned copper coating is generally produced via electrodeposition, with direct current (DC) electrodeposition identified as the most efficient and economical technology. Nevertheless, the present electrodeposition rate is comparatively low. Faraday’s law states that the rate of copper electrodeposition is directly proportional to the current density; however, the performance of the electrolyte establishes a limit on the highest permitted current density. Excessive current density can lead to common copper electrodeposition problems, including burning and nodular coating formation. Consequently, the high-speed, high-quality production of patterned copper coatings remains a significant challenge in modern packaging technologies. To simultaneously enhance both copper electrodeposition rate and copper coating quality, a novel electrolyte formulation was proposed for ultra-high-speed DC electrodeposition of patterned copper coatings, comprising 120 g / L copper sulfate, 60 g / L sulfuric acid, 300 mg / L Polyethylene glycol (PEG, molecular weight 8000), and 6 mg / L Thiazolinyl dithio propane sulfonate (SH110). Incorporating elevated copper sulfate concentrations alongside a precisely calibrated additive system brought about notable improvements in limiting current density and overall copper coating quality. In the Haring cell, the cathode was placed horizontally to improve the uniformity of the copper electrodeposition flow field distribution in the patterns and to minimize mass transport limitations. Additionally, the study incorporated flow field simulations within a Haring cell, along with electrochemical characterization and patterned deposition experiments. Flow field distributions across patterns of varying widths were systematically analyzed. The interactions between additives under different flow intensities and current densities were thoroughly investigated. Optimal conditions for achieving ultra-high-speed, high-quality patterned copper electrodeposition were subsequently identified. The results demonstrate that the photoresist encasing the pattern significantly hinders fluid flow, leading to a marked decrease in flow intensity within the pattern relative to the bulk electrolyte. The flow field indicates a particular distribution, characterized by a lower flow rate at the center and a higher flow rate at the edges, with intensity increasing in relation to greater pattern width and extended electrodeposition time. Regarding additive functionality, PEG functions as a wetting agent and an inhibitor, thereby promoting interfacial adsorption dynamics, facilitating additive dispersion, refining grain structure, and enhancing the thickness uniformity of the patterned copper coatings. SH110 serves as an accelerator, demonstrating particular efficacy in low-convection zones by improving copper electrodeposition rates and reducing the occurrence of voids or seams during pattern formation. PEG and SH110 exhibit a synergistic effect under enhanced convection, which strengthens the electrochemical kinetics and surface morphology control, increasing the limiting current density and cathodic polarization of the electrolyte, which facilitates simultaneous enhancements in the copper electrodeposition rate and coating quality. Regarding the electrodeposition of patterned copper coatings, the process is closely influenced by the time-dependent flow field distributions within the patterns. Initially, copper is deposited at a higher rate at the edges than at the center, followed by a slower rate at the edges. This dynamic ultimately leads to a relatively uniform thickness across the patterned copper coatings. Through a systematic comparison of various electrodeposition parameters, the optimal conditions were identified: a gas flow rate of 0.6 L / min and a current density of 6 A / dm2. Under these conditions, the copper electrodeposition rate exceeds 80 μm / h, producing a dense and uniform coating with a mirror-like surface. For patterns with a line width of 200 μm, the deposition rate surpasses 120 μm / h, achieving a surface roughness of 51.78 nm and a thickness standard deviation of less than 7.33 μm. This advanced patterned copper electrodeposition technology significantly improves the fabrication efficiency of next-generation electronic packaging substrates while offering enhanced reliability and scalability for industrial manufacturing applications.
  • Effect of Substrate Bias on Microstructure and Properties of TiVCrNiSi(N) High-entropy Coating Deposited by Arc Ion Plating
    CUI Menghui, DING Xiaoyun, WU Yawen, CHENG Yingchun, LIAN Yong, ZHANG Jin
    China Surface Engineering. 2026, 39(4): 422-433. https://doi.org/10.11933/CSE2026115
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    Titanium alloys are widely used in the aerospace industry because of their low density, high melting point, and excellent corrosion resistance. However, titanium alloys exhibit low hardness and unsatisfactory wear resistance, thus limiting their application range. Generally, the wear failure of materials begins at the surface. Therefore, the performance of titanium alloys can be effectively improved by preparing high-hardness, wear-resistant coatings on their surface. In this study, a TiVCrNiSi(N) high-entropy coating is prepared on the surface of TC4 via arc ion plating and by changing the substrate bias (0, -100, and -200 V). Scanning electron microscopy and energy-dispersive X-ray spectroscopy are performed to analyze the coating’s cross-sectional morphology, element distribution, and surface morphology after wear. X-ray diffraction (XRD) is performed to determine the phase composition and orientation of the coatings at different bias voltages. X-ray photoelectron spectroscopy (XPS) is performed to determine the form of N in the coating. Transmission electron microscopy (TEM) is performed to observe the fine structure of the coating, and three-dimensional laser confocal microscopy is performed to observe the surface roughness and wear morphology of the coating. A microhardness machine is used to determine the cross-sectional hardness of the coatings. A friction-and-wear testing machine is used to test the wear resistance of the coatings under different substrate bias based on the reciprocating wear. The results show that as the substrate bias increases, the surface roughness of the coating decreases from 0.792 to 0.601 µm, the coating density increases significantly, and the deposition rate decreases from 250.9 to 142.4 nm / min. Owing to the characteristics of arc ion plating and the difference in melting points between the different components in the alloy target, the elements are enriched in different areas of the coating. TEM results show that the coating is composed of columnar crystals and forms amorphous regions composed of Ti, Ni, and Si. XRD results show that the surface coatings under different substrate bias are composed of body-centered cubic (BCC) and amorphous phases, among which the BCC phase grows preferentially along the normal direction of the (110) crystal plane. The N content in the coating decreases from 30.09at.% to 15.33at.% as the substrate bias increases. These results combined with the XPS results suggest the existence of N atoms in the solid solution under -100 V and -200 V substrate biases, as well as N atoms in the form of nitrides under a 0 V substrate bias. Owing to the low nitride content, no diffraction peaks of nitrides are detected in the XRD results. The existence of nanocrystals and the amorphous solid-solution strengthening of N increase the hardness of the coatings. The hardness values of the three coatings deposited under different substrate bias exceed 1 500 HV, which is approximately five times that of the TC4 substrate. The indentation method is used to measure the coating adhesion in accordance with the VDI-3198 Rockwell standard. The adhesion ratings of the three coatings deposited under different substrate bias are HF1, which indicates their excellent adhesion. Owing to the high surface roughness of the coatings prepared via arc ion plating, a large friction coefficient is observed during the wear process. As the substrate bias increases, the wear resistance of the coating increases, and the coating composition is detected on the ZrO2 grinding ball. The layer wear mechanism changes from abrasive to adhesive wear. Under a -200 V bias, the coating demonstrates the lowest wear rate (0.8×10-6 mm3 / (N·m)), which is only 1% that of the TC4 substrate. The TiVCrNiSi(N) high-entropy coating prepared via arc ion plating can effectively improve the wear resistance of TC4 titanium alloys.
  • Optoelectronic Properties of Metal Al, Bi, and Zn Doped CdSe Thin Films
    XUE Yulong, LIU Hui, ZHANG Liuchao, LI Peng, ZHANG Ruiduan, DENG Lechun, LUO Fa
    China Surface Engineering. 2026, 39(4): 434-443. https://doi.org/10.11933/CSE2026196
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    Cadmium selenide (CdSe) is a typical II-VI semiconductor material with excellent photoelectric properties, and is widely used in solar cells, photodetectors, LEDs, and other fields. However, the high resistivity of intrinsic CdSe significantly hinders its application in photoelectric devices. Doping is an effective method for modifying or enhancing the properties of semiconductors. Magnetron sputtering offers advantages such as high repeatability, broad applicability, and high sample purity. Doped CdSe thin films were prepared using radio-frequency magnetron sputtering, and the effects of Al, Bi, and Zn doping on their photoelectric properties were investigated. The phase, morphology, resistivity, carrier concentration, mobility, infrared emissivity, and optical reflectivity of the thin-film samples were characterized using X-ray diffractometry, scanning electron microscopy, four-point probe testing, semiconductor characteristic analysis, ultraviolet-visible-near-infrared spectrophotometry, and dual-band infrared emissivity testing. The results showed that all doped thin-film samples covered the substrate well, exhibited dense growth, had continuous and smooth surfaces, and displayed thickness ranging from 0.37 to 0.42 μm. With increasing Al doping, the grain size of the films changed slightly, remaining smaller than that of the undoped film, with sizes close to 17.50 nm. As the Bi doping level increased, the grain size decreased more significantly. Zn incorporation also led to a slight reduction in grain size. These observations further support the notion that metal impurity atoms hinder grain boundary migration, leading to the formation of smaller grains. As the Al doping level increased, the resistivity of the thin films decreased, due to defect compensation, while the visible-infrared reflectivity remained largely unaffected. In contrast, low levels of Bi doping slightly increased resistivity. However, when the Bi content reached 21.4%, the resistivity decreased significantly. Increasing Bi doping also led to a marked reduction in the visible-infrared reflectivity particularly in the near-infrared region. This is because near-infrared light, which has relatively low photon energy, cannot induce intrinsic excitation in the semiconductor, resulting in low absorption. In contrast, visible light has higher photon energy, which interacts with the semiconductor and is partially absorbed, leading to reduced reflectivity. When the Bi doping level exceeded 7.17%, the infrared emissivity of the thin films in the 3-5 μm wavelength range decreased significantly due to the reduced resistivity. With increasing Zn doping concentration, the resistivity of the thin films first decreased and then increased. Zn incorporation did not significantly affect the electrical conductivity of the films but reacted with Se in CdSe to form ZnSe, which increased the bandgap and reduced reflectivity in the near-infrared range. At a Zn doping concentration of 14.2%, the minimum resistivity of the thin film was 40.7 mΩ·cm. In addition, it was observed that the conductivity of undoped CdSe thin films, as well as those doped with Al and Bi, increased with rising light intensity. As both light intensity and temperature increased, carrier diffusion rates and mobility also increased, enhancing conductivity. However, the conductivity of Zn-doped films was less sensitive to light intensity, likely due to scattering effects from impurity particles that reduce carrier mobility. Overall, the approach of tuning dopant concentrations to modify the photoelectric properties of CdSe thin films is technically viable and holds promise for industrial applications.
  • Application of Galvanic Cell-driven Room-temperature Electroless Nickel Plating for the Development of Oily Latent Fingerprints
    YAO Kunman, WEI Hao, ZHENG Zexiong, LIAO Ying, FENG Caining, ZHONG Dongrong, PENG Jianxin
    China Surface Engineering. 2026, 39(4): 444-451. https://doi.org/10.11933/CSE2026197
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    To address the technical challenges inherent in conventional electroless nickel deposition, particularly the high-temperature requirements that risk damaging the morphological integrity of latent fingerprints and the reliance on complex electrochemical instrumentation requiring specialized infrastructure, this study introduces a galvanic cell-driven, room-temperature electroless nickel plating method for efficient visualization of oily latent fingerprints. This novel approach provides a practical and low-cost solution for developing oil-based latent fingerprints. The core principle of the method lies in the construction of a short-circuited galvanic cell. When a zinc sheet is brought into contact with a metal substrate (e.g., copper or stainless steel), a galvanic cell spontaneously forms due to the difference in metal activity. At the anode, zinc is oxidized, releasing electrons that flow directionally through the external circuit and enhance nickel ion reduction and deposition. This method uses the galvanic cell effect to overcome the dependence of traditional electroless nickel plating on high temperatures or external power supplies and significantly improves imaging efficiency and resolution. This technique has several advantages. During fingerprint development, lipid residues selectively maintain papillary ridge areas in their original substrate coloration, whereas the adjacent furrow regions, which are fully exposed to the deposition environment, accumulate a distinctive silver-gray nickel-phosphorus alloy coating through autocatalytic reduction. The Ni layer is composed of many small cauliflower-shaped particles. The nickel coating forms a continuous deposit in the small furrow area, indicating direct contact between these areas and the plating solution. In this environment, the reduction reaction of NaH2PO2·H2O occurs efficiently, with metallic nickel preferentially depositing to form a coating. This nickel deposition layer is neither uniform nor dense but can form a color difference to reveal fingerprints, clearly revealing secondary / tertiary features such as termination points and sweat pores. To evaluate imaging performance, a computer vision analysis system developed in Python applied a gray gradient algorithm to quantify contrast objectively. The method proved effective on oily fingerprints from various substances (e.g., engine oil, peanut oil, Vaseline). Imaging quality was influenced not just by oil content but also by physical properties like viscosity, film formation, and volatility. High-viscosity oils such as peanut oil achieved the highest contrast (up to 3.004) due to superior shielding. Tests across substrates, including iron sheets, stainless steel, and nickel-plated coins, demonstrated imaging contrast above 2.5. Catalytically active substrates further enhanced deposition rates and vein contrast. Compared with traditional room-temperature electroless nickel plating, which requires approximately 30 min, the galvanic cell-driven method achieved complete deposition in just 4 min, delivering an 85% improvement in operational efficiency without external heating or power. These findings establish a robust foundation for rapid, nondestructive extraction of oily latent fingerprints on various metallic substrates at crime scenes. This technique not only improves evidence preservation but also increases recovery efficiency. Future work will focus on optimizing bath stability and extending compatibility to non-metallic substrates such as plastics, ceramics, and composites, broadening the method’s forensic applicability to diverse materials and scenarios.
  • Tribological Properties of the Bionic Weave of Pangolin Scales in Southern Soil Environments
    DAI Binggui, CHEN Wengang, XIE Xiaoming, LI Zuyang, YANG Xiaodong, ZHANG Yao, ZHANG Jihao, LIU Xiubo
    China Surface Engineering. 2026, 39(4): 452-463. https://doi.org/10.11933/CSE2026198
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    Wear and tear during the operation of agricultural soil tillage implements is one of the most important challenges in agricultural machinery use. However, studies applying 1:1 bionic texture mathematical modeling to examine friction performance are limited. To meet the development needs of agricultural machinery, this study combines a bionic weaving mathematical model with experimental analysis to explore its tribological properties under southern soil conditions. The surface weave structures of pangolin scales were extracted using a three-dimensional morphometer. Through quantitative analysis, a mathematical model of the surface texture of pangolin scales was established. Based on the direction of soil movement over the pangolin scales, a mathematical model of the texture was prepared on the surface of 65Mn steel in a wrap-around manner with a curved cross-section and a 45-degree angle. The horizontal direction of the deep pine shovel was analyzed, and the test load was determined by converting force per unit area. Comparative friction and wear tests of bionic weave 65Mn steel and non-textured 65Mn steel were carried out in a soil environment using a soil sample from Yunnan as the test medium. The effect of rotational speeds (200, 250, and 300 rpm) on the tribological properties of the bionic pangolin weave was investigated under southern soil conditions. The tribological performance of the bionic pangolin fabric at different rotational speeds was evaluated by measuring the friction coefficient and analyzing wear patterns. Results show that the bionic weave reduces fluctuations in the friction coefficient during the friction process at 200, 250, and 300 rpm under southern soil conditions. The friction coefficient of the bionic fabric was smaller and more stable than that of the non-textured 65Mn steel, with a maximum reduction of 19.77% under the same conditions. In addition, the bionic fabric effectively controlled wear, and the amount of wear remained stable at approximately 0.004 g even as rotational speed increased. In contrast, wear on the non-textured 65Mn steel increased with rotational speed. The bionic fabric reduced wear by 28.07% to 79.19% compared with the non-textured samples. The bionic perforated scale weave can trap abrasive particles and block furrow formation, which not only reduces abrasive wear but also protects the oxide layer and soil film formed on the friction surface, thus inhibiting oxidative and fatigue wear. In addition, due to its unique surface structure, the bionic pangolin-scale weave reduces frictional heat on the contact surface. This study analyzed the tribological properties of pangolin scales in the context of their living environment and the working conditions of deep pine shovels. A mathematical model of the pangolin scale texture was developed, and its anti-wear performance was experimentally evaluated during deep pine shovel operation. The results demonstrate that the bionic scale weave significantly improves wear resistance and friction stability, offering valuable insights for designing agricultural soil engagement tools.
  • Wear Degradation Evaluation of Hydraulic Excavator Bucket
    WANG Linlin, WEI Xuefeng, LI Chenchen, WANG Dagang, SUN Yuan
    China Surface Engineering. 2026, 39(4): 464-480. https://doi.org/10.11933/CSE2026154
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    Hydraulic excavators play a vital role in open-pit mining operations. The bucket, as the working component that directly interacts with mineral materials, frequently encounters issues such as poor wear resistance and a limited service life. Moreover, the variability of the excavated materials significantly influences the wear behavior of critical bucket structures. Addressing these challenges, research on the evaluation of wear deterioration in hydraulic excavator buckets is essential for improving wear resistance and extending service life. This study followed a multi-step approach. First, a three-dimensional model of the excavation device was developed with reference to a 120-ton extra-large mining backhoe hydraulic excavator. While retaining the key structural features, components such as the walking device, boom, and arm were simplified. The bucket structure was modeled in details, with auxiliary parts omitted to reduce simulation complexity. A dynamic simulation model was then constructed based on analysis of excavation video footage. The excavation process was divided into four stages, with motion pairs and drivers added to simulate realistic motion trajectories. Material selection for each component was carried out appropriately. To build the material discrete element simulation model, field studies were conducted at four open-pit mining sites. The physical properties of four ore types were measured and applied in the simulations. Contact coefficient measurement devices were independently developed to determine collision restitution, static friction, and rolling friction coefficients. In the EDEM environment, three-dimensional ore models were created, with defined material properties and contact parameters. A slope-material pile model was then established. An ADAMS-EDEM coupling simulation was used to analyze excavation resistance and calculate the distributions of contact forces on the bucket surface. The results showed that the forces were concentrated in regions such as the bucket teeth, main cutting edges, side cutting edges, bottom plates, and side plates. For the wear deterioration analysis, friction and wear experiments were performed between different ore types and the bucket steel material. Experimental parameters were determined based on the simulation outputs. A custom test platform, i.e. an ore-bucket steel material friction wear machine, was designed for this purpose. Results indicated that wear severity increased with increasing friction cycles. Higher contact pressure led to greater wear depth. The extent of wear varied among the ore types: Pingshuodong coarse sandstone caused the most severe damage due to its high hardness and density, while Red Shaquan fine sandstone caused the least wear owing to its relatively low hardness and loose structure. To evaluate wear deterioration, a theory model was developed based on Archard’s wear theory. The wear coefficient was calculated, and wear deterioration models were established for both single- and multi-material scenarios. Model validation was conducted by comparing predicted wear depths with experimental results. Both models demonstrated predictive accuracy exceeding 90%, with the multi-material coupled model, incorporating contact pressure and ore hardness, showing slightly higher precision. The innovation of this research lies in its integrated methodology, combining dynamic simulation, discrete element modeling, and empirical friction and wear experiments to develop a robust wear deterioration model for bucket steel materials. This approach offers valuable guidance for predicting bucket service life. Furthermore, the development of customized contact coefficient measurement tools and friction wear test machines enhances experimental capabilities. The application of Archard’s theory, along with the proposed evaluation models, provides practical solutions for improving the durability and performance of hydraulic excavator buckets in open-pit mining environments.
  • Effect of Deep Cryogenic Treatment Duration on the Microstructure and Tribological Properties of Al0.5CoCrFeNb0.5Ni High-entropy Alloy
    MEI Sikai, YAN Lei, CAI Zhaobing, DONG Yinghui, LIN Guangpei, WANG Bingxu, GU Le
    China Surface Engineering. 2026, 39(4): 481-494. https://doi.org/10.11933/CSE2026148
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    Deep cryogenic treatment (DCT) is an effective method for improving the performance of materials, particularly alloys, as it modifies their microstructures and improve their tribological properties. This technique involves immersing materials in liquid nitrogen at extremely low temperatures, typically -196 ℃, and has attracted attention because of its ease of operation, cost-effectiveness, and environmental benefits. High-entropy alloys (HEAs), which comprise five or more principal elements in nearly equimolar ratios, exhibit excellent mechanical properties. Their potential for various advanced applications has been investigated, particularly regarding their tribological behavior under different treatment conditions. In this study, the Al0.5CoCrFeNb0.5Ni HEA was subjected to DCT via liquid nitrogen immersion at -196 ℃ for varying durations to examine the effect of DCT time on its microstructure, hardness, and tribological properties. Several characterization techniques, such as X-ray diffraction, field-emission scanning electron microscopy, X-ray energy dispersive spectroscopy, microhardness testing, and tribological wear testing, were employed to reveal the structural and mechanical properties of HEA. The experimental results show that the microstructure of the Al0.5CoCrFeNb0.5Ni HEA changed significantly with the duration of DCT. Initially, the grain size increased with treatment time, reached the maximum value, decreased, and then increased again. However, no new phases were observed. Instead, the amount of the BCC phase decreased gradually, indicating that the DCT primarily affected the existing phases rather than introducing new phases. The microhardness of the HEA increased with increasing DCT time because of grain refinement strengthening and solid-solution strengthening. Grain refinement strengthening arises from a reduction in the grain size, which impedes dislocation motion and enhances the hardness of the material. Solid-solution strengthening is attributed to an increase in the solute concentration within the alloy matrix owing to the treatment, further improving its resistance to deformation. The maximum microhardness was 604.01±6.62 HV for the sample treated for 48 h, representing a 10% increase compared to that for the untreated sample, which indicates that prolonged DCT positively influences the microhardness of the Al0.5CoCrFeNb0.5Ni HEA. The tribological performance of HEA is influenced by several factors rather than the direct correlation with variations in microhardness. The sample treated for 6 h exhibited the lowest wear rate ([3.13±0.87] × 10-5 mm3 / N·m), which is 70% lower than that of the untreated sample. In contrast, the sample treated for 12 h exhibited the highest wear rate ([16.63±1.02] × 10-5 mm3 / N·m), which is 60% higher than that of the untreated sample. These findings suggest that other factors, such as phase stability, microstructural evolution, and treatment-induced stresses, also play significant roles in determining the wear behavior of HEA. The wear mechanism changed with the duration of DCT. For samples subjected to shorter treatment times (for example, 6 h), the primary wear mechanisms were oxidation, adhesion, and abrasive wear. These mechanisms occurred owing to interactions between the material surface and the counter bodies under high loads. However, for samples treated for extended durations (for example, 12 h and longer), the wear mechanism shifted towards oxidation wear and fatigue wear. This shift is attributed to prolonged exposure to low temperatures, which induces internal stresses and microstructural changes, making the material more susceptible to fatigue failure under wear conditions. By analyzing the effects of DCT on the microstructure, mechanical properties, and tribological behavior of the Al0.5CoCrFeNb0.5Ni HEA, valuable insights were gained: DCT can improve the hardness and wear resistance of the Al0.5CoCrFeNb0.5Ni HEA, and the optimal treatment time depends on the specific application and desired performance characteristics. These findings contribute to the advancement of HEAs for use in cryogenic environments, such as aerospace, automotive, and cryogenic engineering applications.
  • Fabrication and Tribological Behaviors of Al2O3 / GNPs Coatings
    ZHANG Hua, SUN Junlong, LIU Changxia, WEI Xudong, LI Changye, WANG Huantao, ZHAO Chengliang, LI Xiaoyan, SUN Haobin
    China Surface Engineering. 2026, 39(4): 495-506. https://doi.org/10.11933/CSE2026199
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    With the rapid advancement in industrial production, the demand for wear resistance of key equipment components has become increasingly stringent. In harsh working environments, such as high loads, high speeds, and frequent friction, traditional wear-resistant coatings cannot satisfy the long-term stable operation requirements of industrial equipment. Therefore, the development of new high-performance wear-resistant coatings is urgently required. To address this challenge, suspension high-velocity oxy fuel (SHVOF) thermal spraying technology was employed to deposit Al2O3+1wt.% graphene nanoplatelets (GNPs) coatings on 316 stainless steel substrates. A series of comprehensive performance evaluations were conducted to systematically assess the functionality of the coatings. These included tests on microhardness using a Vickers indenter with a 100 g load and dwell time of 15 s and fracture toughness measurements using indentation methods to evaluate the resistance to crack propagation. Tribological behaviors were investigated using a ball-on-disk tribometer under ambient conditions, with the sliding speed set at 0.5 m/s and the sliding distance set at 1 000 m to simulate real-world wear conditions. The wear trajectory was measured using an Alicona Infinite Focus Advanced 3D system (Raaba/Graz, Austria) to determine the specific wear rate. Five cross-sectional profiles at different positions along the length of the worn track were chosen to obtain the effective area of material loss, which was then multiplied by the track length to calculate the volumetric material loss, thereby providing quantitative data on wear resistance. Multiple characterization techniques were used to analyze the performance and structures of the coatings at various scales. Optical microscopy and scanning electron microscopy were used to observe the wear scar morphology of a sliding alumina ball (6 mm diameter, 99.9% purity) and wear tracks of the coatings, thereby providing direct visual evidence of the wear processes and material transfer mechanisms. X-ray diffraction with Cu Kα radiation was performed to enable phase composition analysis, which verified the stability of the crystalline structures of the coatings after spraying. Electron spectroscopy (EDS) was employed to characterize the elemental distributions in the coatings. Raman spectroscopy was employed to verify the survival of GNPs during the thermal spraying process, detecting characteristic D and G bands at 1 350 cm-1 and 1 580 cm-1, respectively, which confirmed the retention of the intrinsic properties of graphene despite the extreme thermal conditions. The coating thickness, micro Vickers hardness, fracture toughness, and porosity of the alumina+1wt.% graphene coatings were 30 µm, 9.5 ± 2.0 GPa, 2.0 ± 0.7 MPa·m1/2, and 3.5 ± 0.3%, respectively. A surface microstructure image showed that the sprayed alumina+1wt.% graphene coatings underwent certain deformation, mostly presenting as thin flakes. EDS elemental analysis detected the presence of Fe, O, and Al elements. Fe mainly originated from the substrate, whereas O and Al originated from the coatings. The friction and wear results showed that the wear rate of 316 stainless steel after surface coating decreased by an order of magnitude under a load of 5-20 N compared to that before coating. The alumina+1 wt.% graphene coatings greatly improved the wear resistance of 316 stainless steel. Analysis of the wear mechanisms revealed distinct differences: the wear mechanism of 316 stainless steel was plowing and adhesive wear, whereas the wear mechanism of the alumina+1wt.% graphene coating was abrasive wear and coating peeling. This research was the first application of SHVOF technology for preparing alumina/graphene coatings and confirmed the survival of graphene during high-temperature spraying, thereby offering a promising solution for improving the wear resistance of metallic substrates. The superior performance of the developed coatings highlights their significant application prospects in key industrial fields requiring high wear resistance. Some examples are ship propellers operating in marine environments where saltwater accelerates wear, hydraulic blades in heavy machinery subjected to continuous loading, and exhaust valve stems in engines exposed to high temperatures and mechanical stress. These are areas where enhanced wear resistance can deliver substantial economic and safety benefits.
  • Investigation and Improvement of Latent Defects of Ablative Thermal Protection Coatings for Airborne Missiles
    XIAO Jun, LIAO Zhizhong, CHEN Jianmin, ZHOU Huidi, LIU Jie, YU Zhimin, LI Chenguang, CHENG Gong
    China Surface Engineering. 2026, 39(4): 507-519. https://doi.org/10.11933/CSE2026339
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    Thermal protection materials and manufacturing technologies underpin the tactical and technical performance, mass production, delivery, deployment readiness and integrated logistical support of high-speed airborne missiles. Independent development and batch production are frequently plagued by various defects and faults. Among them, random, recurrent, latent blistering failures of thermal protection coatings are typical concealed failures. This paper analyzes the adverse effects of such failures on development progress, performance and critical airborne testing activities of the missile system, as well as potential risks to normal operation, combat effectiveness and integrated logistics support in harsh service environments, special mission profiles and life-cycle profiles. Where conventional methods for rectifying common and apparent faults are ineffective for such failures, and considering the technical difficulty and inherent complexity of the engineering issue, a set of fault closure and technical tackling breakthrough measures, including 4M1E analysis, fault tree analysis and environmental verification tests is adopted. Focusing on the identified fault causes, corrective actions and improvement schemes, the main experimental studies are implemented as follows: (1) Control ambient temperature and humidity at the construction site during coating processes to eliminate failure risks induced by moisture ingress during coating process; (2) Pre-dry the fillers for coating to remove the adverse effects of inherent moisture inside the coatings; (3) Select and optimize three-proof coating (outer protective coating for environmental adaptability) for the thermal protection coatings to enhance environmental adaptability; (4) Investigate anti-blistering technologies by increasing or decreasing the thickness of three-proof coating films; (5) Analyze coating components, coating formulation and their hygroscopic characteristics, and develop anti-blistering technologies via filler particle size control, grinding, sieving treatments and hydrophobic modification of hygroscopic fillers; (6) Explore supplementary thermal curing techniques to enhance the crosslinking degree of coating resins; (7) Adopt waxing, polishing and film coating techniques to inhibit blistering failures; (8) Add fillers such as graphene and mica into coatings to improve moisture and water resistance; (9) Construct gradient anti-permeability layers composed of multiple primers, topcoats and transition layers to prevent blistering defects; (10) Conduct environmental verification tests and corresponding data analysis; ⑾ Carry out research on failure mechanisms, including the correlation between latent blistering failures in damp heat environments, surface defects of coatings and failure formation mechanisms. The above blistering failures show a moderate correlation with temperature and humidity, while cross-contamination during coating processes is identified as the dominant cause. The location, type and severity of failures are closely correlated with multiple factors related to the product contamination history, including placement position, posture, contamination mode, category and quantity of adhered contaminants, as well as working procedures and ambient conditions. Contamination may arise from single or multiple coating stages: post-cleaning drying, priming, thermal coating, topcoating and rework procedures, resulting in blisters on primer blistering, thermal layer blistering, three-proof coating blistering and composite blistering in damp heat environments. Under high-temperature ablation, contaminated interfaces among thermal protection coatings and shells or primers suffer debonding, bulging and peeling, which are consistent with the abnormal phenomena observed in previous hot wind tunnel and aerial flight tests. Distinguished from conventional laboratory material tests and simple process verification studies, this work features prominent engineering practicality in latent failure characterization, technological tackling, multi-surface engineering tests, environmental assessment and applied exploration. The clarified failure mechanisms reveal the origins and formation principles of random, latent blistering in damp heat environments, as well as blistering and peeling anomalies occurring during high-temperature ablation. The research findings explain all failure phenomena, laying a solid foundation for closed-loop fault rectification, advancing the development progress, and achieving high-quality and high-reliability batch production, product delivery and integrated support. They also provide a basis for preventing potential risks and losses of manufactured and delivered products with hidden defects. The relevant engineering experiences provide technical support for the R&D of new materials and new processes, and have favorable engineering reference value.
  • Early Failure Law of Typical Offshore Wind Power Coating Systems Based on Electrochemical Impedance
    WANG Jun, LIU Miaoran, JIE Ganxin, ZHONG Zhenkun, GUAN Lei
    China Surface Engineering. 2026, 39(4): 520-529. https://doi.org/10.11933/CSE2026091
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    In recent years, the offshore wind power industry has developed rapidly. Anticorrosion work has become a key and difficult task in the wind power industry. Currently, coating offshore wind turbines in atmospheric areas is the primary anticorrosion measure. However, marine atmospheric coatings are prone to aging failure owing to harsh environmental factors, such as salt spray, humidity, and light, whereas the topcoat, which is the outermost layer of the coating system, is susceptible to erosion by corrosive factors, which results in aging damage or even failure. If the coating system is not maintained in time, once the coating system fails as a whole, the pile of the wind turbine will be corroded and damaged, resulting in heavy losses. Therefore, it is necessary to effectively monitor and warn of early coating failures to achieve timely and efficient maintenance. Monitoring and early warning technology is mainly based on electrochemical impedance technology. The evolution law of coating aging and failure is proposed, and the corresponding characteristic parameters are monitored and warned early. Therefore, accelerated indoor cyclic aging experiments of ultraviolet condensation, high-humidity salt spray, and low-temperature exposure were carried out on four typical organic anticorrosion coating systems for offshore wind power towers. These experiments were combined with existing standards and experimental characterization methods to highlight the early aging phenomenon of the coating. The scratch expansion width, macroscopic morphology, and cross-sectional morphology were observed, the color difference of the loss rate was determined according to the standard, the aging grade was evaluated, the topcoat composition was determined, and a nondestructive electrochemical impedance test was carried out. Combined with the experimental results, the early aging evolution of the electrochemical impedance test parameters of the coating was explored, and a characteristic parameter that conforms to the early aging of the coating was proposed according to the evolution law. The early aging state of the coating was evaluated according to this characteristic parameter, which provided a theoretical basis for monitoring the early aging failures of organic coatings. Combined with the results of previous studies, the characteristic parameters that do not require fitting treatment and can be obtained quickly are selected, and the universal electrochemical impedance characteristic parameter evaluation table for the rapid evaluation of the protective performance of the coating system for offshore wind power towers is summarized, laying a foundation for the intelligent online monitoring of the aging states of the coatings of offshore wind power towers. The results showed that after 16 cycles of accelerated indoor cyclic aging, the D, P, and Z coating systems were in a good nondestructive state and still had good corrosion resistance, whereas the N coating was in an early damage state and showed signs of deterioration and reduced corrosion resistance. The phase angle of the electrochemical impedance parameter and its change rate with the test period are closer to other experimental results than is the low-frequency impedance modulus. Thus, the phase angle and its change rate with the test period can be used as a basis for judging the early aging failure information of the coating as well as facilitating the judgment of the aging state of the coating topcoat to accurately provide early damage warnings for coatings. Based on photoaging and water-aging mechanisms, it is proposed for the first time that the combination of the phase angle in the electrochemical impedance parameters and its rate of change with the test period and low-frequency impedance modulus can be used as a criterion for predicting the early damage of coatings.
  • CFD-DEM Coupling Magnetic Field-assisted Magnetorheological Finishing Process for Variable Diameter Tube Experiment
    SHEN Qiushi, GUO Longwen, CUI Zihan, XIAO Chunfang, HAN Bing
    China Surface Engineering. 2026, 39(4): 530-541. https://doi.org/10.11933/CSE2026147
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    Pipe reduction is crucial in fluid transport systems, where flow rate and velocity regulations are achieved by adjusting the diameter of the flow path. However, defects such as wrinkles, cracks, and burrs often form on the inner surface of pipes during manufacturing. These surface imperfections can lead to increased energy loss during fluid transport as turbulent flow and friction intensify owing to the uneven inner surface. This reduces the efficiency of fluid transfer and accelerates wear and tear, ultimately shortening the lifespan of the pipeline. As a result, the presence of these defects significantly limits the practical applications of concentric reducer, particularly in industries where energy efficiency and durability are critical. To overcome the challenges of achieving a smooth finish and maintaining uniformity on the inner surface of concentric reducer, a magnetic-field-assisted abrasive-flow-finishing method is employed in this study. This technique uses magnetic abrasive particles as the finishing medium, with the particles transported by fluid flow. The rotating magnetic poles provide the driving force necessary for polishing, and by adjusting the inlet pressure, the renewal of magnetic particles within the pipe is achieved. A finite element method (FEM) is used to simulate the rotating magnetic field, compile the data, and load it into a computational fluid dynamics-discrete element method (CFD-DEM) multifield coupling model. This coupling model enables simultaneous simulation of magnetic, particle, and flow fields, providing insights into their interactions and effects. By solving for the motion state and behavior patterns of magnetic abrasive particles within the coupled magnetic flow fields, a dynamic simulation of magnetic field-assisted abrasive flow finishing on the concentric reducer is achieved. The process is particularly challenging in smaller-diameter sections of the pipe because of their distance from the magnetic poles, making them less accessible for finishing compared to larger-diameter sections. Therefore, the optimization of finishing parameters focused on achieving the ideal processing parameters for small-diameter sections. With these optimized parameters, the surface roughness of the entire concentric reducer could be minimized while maintaining uniformity. The Box-Behnken design within the response surface methodology (RSM) was applied to determine the optimal processing parameters for both the small- and large-diameter regions of the pipe. The RSM analysis yielded linear regression equations for each region, enabling the identification of the necessary parameters to achieve the desired surface roughness in the small-diameter area based on the regression model for the large-diameter area. The results demonstrated that, in the optimized setup, the magnetic field strength reached 221 mT in the small-diameter area and 304 mT in the large-diameter area. When the flow-field pressure was set to 1000 Pa, magnetic forces were applied to process the inner surface. At a flow-field pressure of 8000 Pa, the fluid flow moved the magnetic abrasive particles to achieve particle renewal within the system. The response surface optimization provided the best process parameters as follows: a magnetic yoke rotation speed of 720 rpm, processing time of 100 min for the small-diameter area, 45 min for the large-diameter area, and a feed rate of 1.6 mm / s. With these parameters, the initial surface roughness Ra\text{Ra}Ra of the small-diameter area was reduced from 0.673 μm to 0.213 μm, whereas that of the large-diameter area was reduced from 0.686 μm to 0.208 μm. Magnetic field-assisted abrasive flow finishing of concentric reducer can effectively improve the surface quality and ensure uniformity in processing, making it a promising technique for enhancing the performance and durability of concentric reducer in fluid transport applications.
  • Experimental Study on Inner Surface of Elongated Tubes Ground by Magnetic Particles via Halbach Arrays
    HAN Bing, TANG Jiabin, YANG Haiji, YING Jun, SHEN Qiushi, JIN Yuhang
    China Surface Engineering. 2026, 39(4): 542-555. https://doi.org/10.11933/CSE2026116
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    This study introduces the concept of a sectorial ring-shaped conformal magnetic pole to address the challenges of insufficient grinding pressure and inefficient grinding encountered during the magnetic abrasive finishing (MAF) of surfaces inside SUS 304 elongated tubes. The innovative design of the magnetic pole aims to enhance the performance of MAF. To optimize the magnetic-field distribution and improve the magnetic flux density, Halbach-array configurations are implemented on sectorial ring-shaped magnetic poles with three, five, and eight segments. The effectiveness of the Halbach array in magnetic excitation is comprehensively investigated and compared with conventional north-south (N-S) and north-north (N-N) arrangements through simulations using the Maxwell finite-element software. The results of these simulations substantiate the significant advantages of the Halbach arrangement. Additionally, the dynamic behavior of magnetic particles under Halbach arrangements with varying pole numbers is simulated using the EDEM discrete-element software. This study focuses on analyzing the grinding pressure, cutting force, and material-removal rates exerted on the internal surface of the tube to ascertain the most effective pole configuration. Subsequently, experimental validation is conducted to corroborate the outcomes predicted by the simulations. The simulations and experiments show that the magnetic flux density achieved under Halbach arrangements, irrespective of whether three, five, or eight magnetic poles are utilized, is 1.5 times greater than that achieved under the conventional N-S and N-N arrangements. Additionally, the axial distribution of the magnetic flux density along the tube surface is more uniform when Halbach arrangements are employed. The discrete-element simulations indicate that the grinding pressure and cutting force on the internal tube surface under the five-pole Halbach arrangement are greater than those under the three- and eight-pole configurations. Moreover, the magnetic particles exhibit a more dynamic behavior within the tube under the five-pole arrangement, thus improving the cutting efficiency by promoting the regeneration of cutting particles. After 60 min of continuous grinding, the internal surface roughness of the tube reduces significantly to 0.441 and 0.897 μm under the three- and eight-pole arrangements, respectively, which correspond to reductions of 70.6% and 40.2%, respectively. By contrast, the surface roughness reduces further to 0.181 μm when the five-pole arrangement is utilized, which represents a substantial reduction of 89.9%. Surface defects are entirely eliminated, and the maximum surface height difference is reduced to 80.1 μm. The congruence between the simulation and experimental results confirms that adopting the five-pole Halbach arrangement substantially enhances the grinding efficiency and surface quality of the surface inside SUS 304 elongated tubes. This study reveals that the improved grinding performance achieved using the five-pole configuration is attributable to the intensified magnetic flux density and the dynamic behavior of magnetic particles within the tube, both of which contribute to a higher grinding pressure and cutting force. By implementing the five-pole Halbach arrangement, both the efficiency and quality of MAF for SUS 304 elongated tubes improved significantly. The superior performance of the five-pole configuration highlights the potential of optimized Halbach arrangements in overcoming the limitations of conventional magnetic-pole configurations. These findings provide significant insights into the advancement of MAF technology and support its application in precision finishing processes for elongated tubular components, thereby creating new avenues for enhanced manufacturing practices.
ISSN 1007-9289　CN 11-3905/TG
Supervised by: China Association for Science and Technology
Sponsored by: Chinese Mechanical Engineering Society
Edited and Published by: Editorial Office of China Surface Engineering
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