23 August 2025, Volume 38 Issue 4
    

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  • Advances in the Regulation of Adhesion on Superhydrophobic Surfaces
    XU Xinzhe, HUANG Hu, AN Hong
    China Surface Engineering. 2025, 38(4): 1-22. https://doi.org/10.11933/j.issn.1007-9289.20241125002
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The precise modulation of adhesion properties on superhydrophobic surfaces is recognized as a critical pathway for advancing functional surface engineering, with extensive applications in mechanical, aerospace, and biomedical engineering. In this context, the adhesion behavior of water droplets interacting with engineered surfaces is systematically summarized, with particular emphasis on the influence of surface microstructures, chemical compositions, and external stimulation on the adhesion of superhydrophobic surfaces. By drawing inspiration from natural superhydrophobic biological systems, such as lotus leaves, rose petals, and butterfly wings, which exhibit tailored adhesion properties, the fundamental mechanisms underlying solid-liquid adhesion behavior are elucidated, and advanced strategies for its modulation are developed. Currently, advanced characterization techniques have been standardized to quantify adhesion forces and validate modulatory mechanisms between solid and liquid. Contact angle (CA) measuring instrument systems are utilized to measure the minimum angle at which a water droplet begins to slide on an inclined surface, with a high-speed camera capturing dynamic water droplet behaviors during sliding. Adhesion measuring instruments coupled with a high-speed camera enable the nanoscale mapping of adhesion forces under controlled water droplet volume and speed of motion of the carrier table conditions. In addition, computational fluid dynamics (CFD) simulations are employed to model the solid-liquid interactions, providing insights into the mechanisms affecting adhesion on the superhydrophobic surfaces. The adhesion behavior between solid and liquid is primarily governed by the surface microstructures and chemical composition. The surface microstructures with different shapes are fabricated through laser irradiation, template replication, or lithography technologies. For instance, microstructures with various geometries are fabricated through precise adjustments of laser processing parameters, such as energy density, scanning pitch, and scanning speed, to enhance air entrapment and minimize solid-liquid contact areas. Concurrently, densely arranged micropillar arrays or porous networks are designed to change the solid-liquid contact state, enabling controlled water droplet pinning or directional transport. In addition, the transformation between low-adhesion superhydrophobic surfaces and high-adhesion superhydrophobic surfaces is further modulated by changing the chemical composition of the surface. Self-assembled monolayers (SAMs) terminated with fluorinated groups or silane derivatives are uniformly applied to reduce the surface energy, integrating stimuli-responsive polymers, such as pH-sensitive polyelectrolytes or thermoresponsive poly(N-isopropylacrylamide) (PNIPAM), to enable dynamic adhesion transitions. A synergistic combination of structural patterning and chemical modification is demonstrated to generate adhesion patterns for programmable water droplet manipulation, as exemplified by spatially selective plasma etching followed by region-specific silanization. Furthermore, external stimulation, including light irradiation, magnetic fields, and temperature variations, is employed to achieve reversible and real-time modulation of adhesion on the superhydrophobic surfaces. Photoresponsive surfaces embedded with azobenzene derivatives or titanium dioxide (TiO2) nanoparticles are engineered to undergo light-triggered adhesion transforms. Under ultraviolet (UV) illumination, azobenzene-modified surfaces exhibit cis-trans isomerization, which alters the adhesion properties, whereas TiO2-coated surfaces leverage photocatalytic decomposition to remove hydrophobic layers, enabling dynamic switching between low and high adhesion states. Similarly, thermoresponsive coatings are designed to undergo hydrophilic and hydrophobic transitions above specific critical temperatures, thereby facilitating temperature-dependent adhesion control. Magnetic field-responsive superhydrophobic surfaces are constructed by embedding ferrofluids or paramagnetic particles into superhydrophobic matrices, which allows noncontact water droplet manipulation through external magnetic gradients. The method of modulating surface adhesion through electric fields has been developed to modulate the solid-liquid contact state via applied voltages, achieving precise solid-liquid adhesion transformation. Practical implementation of tunable adhesion superhydrophobic surfaces is demonstrated across diverse domains. In microfluidic systems, programmable adhesion gradients have been engineered to guide water droplet routing for high-throughput bioassays, whereas ice-phobic superhydrophobic surfaces with tunable adhesion have been developed to mitigate ice accretion on aerospace components. Self-cleaning technologies exploit low-adhesion superhydrophobic surfaces to achieve contaminant removal by sliding water droplets, whereas high-adhesion superhydrophobic surfaces are tailored for targeted drug delivery, thereby enabling the non-destructive release of site-specific therapeutic agents. This review emphasizes the importance of research on the mechanisms and methodologies of adhesion modulation on superhydrophobic surfaces. By addressing the existing challenges and integrating emerging technologies, the development of tunable adhesion superhydrophobic surfaces exhibits excellent prospects for advancing developments across various scientific and engineering disciplines.
  • Progress of Research in Surface Microfabrication Technology Using Atmospheric-pressure Cold Plasma Jet
    WANG Tao, WANG Ziting, XU Xuezhang, SHI Liping, LI Meng, RAO Sixian
    China Surface Engineering. 2025, 38(4): 23-41. https://doi.org/10.11933/j.issn.1007-9289.20241119001
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    The rapid development of flexible electronics, microelectromechanical systems (MEMS), and integrated circuits has led to a pressing demand for surface microfabrication of materials. Existing chemical wet processes or low-pressure plasma processing technologies have been widely used for surface microfabrication; however, these microfabrication technologies have certain shortcomings, such as complex processes, high processing costs, low energy efficiency, and environmental unfriendliness. To achieve patterned surface microfabrication, traditional microfabrication methods require the use of masks or photolithography processes which limit the efficiency and application scope of the microfabrication method. Therefore, there is an urgent need to explore new surface microfabrication methods that are low-cost, green, maskless, versatile, and noncontact. An atmospheric-pressure cold plasma jet is a plasma plume formed using the action of airflow and an electric field to produce plasma in the discharge region and eject it from an orifice at a low gas temperature. Atmospheric-pressure cold plasma jet microfabrication technology is found to be advantageous because it is environment-friendly, low-cost, low-temperature, strongly reactive and pure dry method having no mechanical contacts. Atmospheric-pressure cold plasma jets have been widely used in localized surface modification, maskless surface etching, and direct deposition of functional thin films. However, microfabrication still faces challenges in terms of plasma jet stability, processing accuracy, and collaborative processing. Therefore, it is extremely essential to explore the research progress, existing problems, and future development trends in the generation mode, surface microfabrication methods, and processes related to atmospheric-pressure cold plasma jets. Firstly, the generation modes and commonly used electrode structures of atmospheric-pressure cold plasma jets were summarized and analyzed. By comparing the characteristics of four common discharge modes, namely, corona discharge, dielectric barrier discharge, arc discharge, and spark discharge, the commonly used discharge mode that generates an atmospheric-pressure plasma jet was demonstrated. Furthermore, the characteristics and applicable scenarios of single-needle, ring, needle-ring, and plate-plate type electrode structures were analyzed. Then, the research scenario of surface microfabrication technology of atmospheric-pressure cold plasma jets on surface modification, material etching, and film deposition was elaborated. Plasma jet surface modification is a general “equal material processing” method. According to the different modified surfaces, the application of plasma jets in material modification research can be roughly divided into three aspects: modifying the substrate to meet specific requirements, modifying the functional layers of devices to achieve specific functional requirements, and as an auxiliary processing method, providing assistance for other surface microfabrication methods. Herein, a systematic summary and analysis of the three surface modifications are presented. Atmospheric-pressure cold plasma jet etching, as a “subtractive processing” method, can etch substrates and also selectively etch some functional layer materials. In addition, the etching mechanism of an atmospheric-pressure cold plasma jet is summarized and discussed. As an “additive processing” method, a comprehensive review of atmospheric-pressure cold plasma jet surface deposition is also presented. This method can deposit various types of thin films or coatings with different properties, such as organic polymer, inorganic and conductive metal thin films. Finally, the main challenges that exist in plasma jet surface microfabrication technology are discussed, and its future development direction is highlighted. This review can be used as a basis for more in-depth research on methods and technologies for the surface microfabrication of atmospheric-pressure cold plasma jets and to improve the application level of atmospheric-pressure cold plasma jets in advanced manufacturing fields such as flexible electronics, MEMS, and integrated circuits.
  • Environmentally Friendly Method and Mechanism for Transforming the Hydrophobic Properties of Metals via Nanosecond Laser Processing
    WANG Jiqiang, XU Yanhua, GAO Yunli, YAN Yongda, GENG Yanquan
    China Surface Engineering. 2025, 38(4): 42-63. https://doi.org/10.11933/j.issn.1007-9289.20250513001
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    Nanosecond laser direct writing (NDLW) is an advanced surface processing technique that utilizes high-energy nanosecond pulsed lasers to induce localized modifications on metallic materials. Due to its ability to precisely control surface morphology through mechanisms such as laser ablation, photothermal, and photochemical reactions, NDLW has been widely adopted in the fabrication of microscale surface structures. When applied to polished metal substrates, NDLW typically results in a highly (super)hydrophilic surface due to the formation of oxides and increased surface roughness. However, these laser-induced surfaces can undergo further wettability transformation toward (super)hydrophobicity through post-treatment strategies that are environmentally friendly and free of chemical modifiers. In recent years, there has been growing interest in developing green, sustainable methods to regulate surface wettability, especially for applications in aerospace, biomedical engineering, and energy systems. These applications demand robust, durable, and multifunctional surface properties, including anti-icing, self-cleaning, antibacterial, and drag-reduction functionalities. Unlike traditional chemical modification methods that involve hazardous fluorinated compounds or silanes, emerging approaches focus on physically driven processes such as air exposure, thermal annealing, and secondary laser treatments to modify surface chemistry and energy without introducing environmental burdens. This paper provides a comprehensive overview of the theoretical basis of wettability, including classical models such as the Young, Wenzel, and Cassie-Baxter models, and elaborates on the role of surface roughness and surface energy in determining hydrophobic or hydrophilic behavior. Special attention is given to the mechanisms by which nanosecond laser processing induces micro / nano-hierarchical structures and alters surface states on metals such as titanium, aluminum, stainless steel, and copper. Subsequent to NDLW, environmental exposure often results in gradual absorption of low-surface-energy organic compounds from ambient air. This spontaneous aging process, albeit slow (often taking weeks), transforms laser-textured metal surfaces into superhydrophobic states, as confirmed by contact angle measurements and surface chemical analyses using XPS. To accelerate this transition, low-temperature annealing has been widely studied. Heating laser-treated samples in air at moderate temperatures (100-200  ℃) significantly shortens the hydrophilic-to-hydrophobic transition period by facilitating the decomposition and adsorption of airborne hydrocarbons and by reducing the concentration of polar hydroxyl groups on the surface. Another effective and scalable method involves secondary laser treatment. This technique enhances the complexity and dual-scale nature of the surface textures, leading to a more stable Cassie-Baxter state. Furthermore, advanced laser interference strategies, such as direct laser interference patterning (DLIP), can precisely fabricate periodic structures, improving water repellency and surface durability. Hybrid techniques like combining NDLW with ion implantation have demonstrated superior performance. For instance, post-laser carbon ion implantation not only modifies surface energy but also improves mechanical robustness and corrosion resistance, enabling the formation of long-lasting superhydrophobic surfaces suitable for harsh environments. The findings reviewed in this study demonstrate that nanosecond laser-based surface texturing, followed by eco-friendly post-treatments, offers a versatile and sustainable route to engineer functional metallic surfaces without relying on hazardous chemicals. The resulting superhydrophobic surfaces exhibit excellent durability, tunable wettability, and enhanced environmental compatibility. In conclusion, this work outlines the fundamental mechanisms, recent advancements, and technological trends in the field of laser-induced wettability engineering on metallic substrates. It highlights the synergy between laser-generated microstructures and environmentally benign surface modifications, providing a valuable reference for future research and industrial applications aimed at achieving high-performance and sustainable surface functionalities.
  • Fabrication Technology of Arrayed MoS2-Au-square Composite Surface-enhanced Raman Scattering Substrates
    ZHANG Jingran, BI Yanrui, JING Bowen, QIAO Jian, YU Miao, SHI Guangfeng, LI Jing
    China Surface Engineering. 2025, 38(4): 64-73. https://doi.org/10.11933/j.issn.1007-9289.20250302002
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    The detection of myoglobin holds significant importance in the prevention of acute myocardial infarction (AMI). Myoglobin is recognized as a primary biomarker for AMI prevention. Owing to its small molecular size, myoglobin is released into the bloodstream within 1 h after the onset of chest pain and reaches peak levels within 2 h, whereas troponin and creatine kinase are released after 3 h and 6 h, respectively, thereby establishing myoglobin as a more accurate biomarker for AMI diagnosis. In recent years, surface-enhanced Raman scattering (SERS) technology has been widely adopted for biomolecule detection owing to its advantages of nondestructive analysis, high sensitivity, and rapid response. Noble metal / two-dimensional material composite SERS substrates not only exhibit high enhancement effects of noble metals but also benefit from the strong fluorescence quenching capability, high adsorption capacity, and large specific surface area of 2D materials. Additionally, three-dimensional micro/nanostructures are known to enhance SERS substrate performance, with the enhancement effects closely related to the dimensions of these structures. In this study, a composite SERS substrate comprising a molybdenum disulfide-gold-square array structure is fabricated via a combination of focused ion beam (FIB) etching, magnetron sputtering, and drop-coating methods. This substrate is designed for the label-free and highly sensitive detection of the biomolecule myoglobin, offering potential applications in biotherapy and medical diagnostics. First, a nanoarray structure is fabricated using FIB technology. The system is equipped with an electron beam imaging resolution of 0.8 nm, an ion beam imaging resolution of 4 nm, and a machining accuracy of 5 nm. A gallium ion source is employed with an acceleration voltage of 30 keV, a beam current of 24 pA, and a dwell time of 2 μs. Square array structures with varying side lengths (300, 350, and 400 nm), spacings (424, 495, and 566 nm), and depths are etched onto a clean silicon substrate. Subsequently, gold nanoparticles are deposited onto the square array structure via magnetron sputtering using a high-vacuum coating system. This process forms a gold-square array structure with localized surface plasmon resonance (LSPR) effects, significantly improving the detection resolution of the SERS substrate. The sputtering power is set to 150 W, with argon gas used as the working medium. Finally, a MoS2 solution is drop-coated onto the gold-square array structure, allowed to spread uniformly, and air-dried to form a MoS2-Au-square array composite SERS substrate. The square array structures and MoS2-Au-square array composite SERS substrate are characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). For square arrays with side lengths of 300, 350, and 400 nm and spacings of 424, 495, and 566 nm (denoted as L1S2, L2S5, and L3S6, respectively), the overall morphology remains unchanged, exhibiting a state of adjacent contact. When the side length is fixed at 300 nm and the spacings are varied (504, 424, 344, and 264 nm), the adjacent arrays transition from separated to overlapping states. The SEM analysis of the composite substrate confirms a uniform coverage of the MoS2 film within the gaps and interior of the square arrays, verifying successful film adhesion. Raman spectroscopy and energy-dispersive X-ray spectroscopy (EDS) further validate the presence of characteristic MoS2 peaks and elemental composition, confirming the successful fabrication of the composite substrate. The Raman performance of the gold-square array and MoS2-Au-square array composite substrates is investigated using rhodamine 6G (R6G) as a probe molecule. The results indicate that the Au-L1S2 substrate (300 nm side length) exhibits stronger Raman signals compared to Au-L2S5 and Au-L3S6. Similarly, the Au-L1S2 substrate with a 424 nm spacing outperforms Au-L1S1, Au-L1S3, Au-L1S4, and Au-L1S5. The MoS2-Au-L1S2 composite substrate demonstrates the highest signal enhancement. This substrate achieves a detection limit of 10-8 mol / L for R6G, with a relative standard deviation (RSD) of 4.66%. After 7 d and 30 d of storage, the Raman intensities at 613, 1 362, and 1 650 cm-1 decrease by 9.7% and 47.6%, 5.6% and 41.8%, and 8% and 45.5%, respectively, demonstrating excellent sensitivity, uniformity, and stability. Furthermore, the composite substrate successfully detects myoglobin at a concentration of 0.02 μg / mL that is below the threshold observed in AMI cases, highlighting its potential for high-sensitivity and uniform biomarker detection.
  • Filling Behavior in Glass Molding of Microlens Arrays
    ZHU Zhiwei, LI Kaimin, LI Hongchi, ZHANG Lin, ZHU Limin, XU Jianghai
    China Surface Engineering. 2025, 38(4): 74-85. https://doi.org/10.11933/j.issn.1007-9289.20241231002
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    Glass microlens arrays are widely used in consumer electronics, biosensing, and optical imaging. Glass molding technology is considered a promising manufacturing method for the mass production of glass microlens arrays owing to its efficiency and cost-effectiveness. However, the complex structures of microlens arrays present significant challenges to the molding process, particularly related to non-uniform glass filling and complicated stress distributions, directly affecting the quality of the microlenses formed. This study aimed to optimize the molding process by investigating the glass-filling behavior during microlens array formation through a combination of finite element simulation and experimental study. A finite element model of glass molding was developed to explore the effects of process parameters--such as molding temperature, molding rate, friction coefficient, and lens center spacing--on the filling behavior and stress distribution within microlens arrays. The simulation results revealed that these parameters significantly influenced molding quality, emphasizing the importance of their optimization to achieve uniform microlens arrays. Numerous experiments were conducted to validate the simulation model, demonstrating the consistency between simulated and experimental outcomes, thus confirming the accuracy of the model. Based on these findings, the molding process parameters were optimized, and several conclusions were drawn from the experiments. First, lower molding temperatures decreased glass forming performance. When the molding temperature reached 550 ℃, further increases had minor influence on glass filling performance but reduced internal glass stress. Increasing the molding rate had a minor impact on glass filling capability but tended to increase internal stress. Second, the filling uniformity of microlens arrays was significantly influenced by the friction coefficient at the interface. Reducing the friction factor significantly improved filling uniformity but substantially decreased the filling depth of the microlens arrays. When the friction factor was below 0.1, the internal stress of the glass significantly increased, whereas the stress remained within the range of 25-30 MPa when the friction factor was between 0.1 and 0.3. The distance between the microlens arrays affects the glass filling. An increase in the distance between the microlens arrays results in an increase in the resistance gradient at different lens positions, thereby reducing the uniformity and filling depth of the microstructures while having minimal impact on the internal stress of the glass. Finally, a uniform microlens array was successfully fabricated from a D-ZK2 glass preform using a molding temperature of 550 ℃, molding rate of 0.01 mm / s, and pressing depth of 110 m. The resultant microlens array exhibited a surface roughness (Sa) of 4.2 nm, single lens profile peak-to-valley error of approximately 1.6 μm, and an imaging resolution of 203.2 lp / mm, thus meeting high-performance optical component requirements. This research provides substantial technical support for the mass production of glass microlens arrays and valuable insights into the molding of optical elements with complex structures. As glass molding technology continues to advance and mature, the application of glass microlens arrays is expected to expand across various fields, significantly contributing to the prosperity of the optical industry. This study underscores the significance of process parameter optimization to achieve high-quality molding outcomes. Careful management of molding temperature, rate, and friction is essential for uniform filling and minimal stress concentrations. The validated optimized process can enhance the structural integrity and optical performance of the microlens arrays, critical for the applications of high-resolution imaging and precise light control. In conclusion, combining finite element modeling and experimental validation has proven effective for understanding and optimizing the glass molding process of microlens arrays. These findings contribute to the body of knowledge in precision optics manufacturing and facilitate the development of improved optical components for diverse applications.
  • Surface Properties and Influence Mechanism of Superhydrophobic SiC Surface Prepared by Laser-chemical Composite Process
    SONG Xinrong, SHI Zhe, GUO Xiaozhe, LI Ziang, FU Jiajun, WANG Qinghua
    China Surface Engineering. 2025, 38(4): 86-103. https://doi.org/10.11933/j.issn.1007-9289.20241016002
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    As one of the most popular advanced functional ceramics, silicon carbide (SiC) has many excellent characteristics, such as low coefficient of expansion, high thermal conductivity, and radiation resistance. In recent years, brake materials prepared using SiC have been widely used in braking systems such as cars and aircraft. However, owing to its high hardness, SiC is difficult to process using conventional methods. At the same time, the intrinsic hydrophilic characteristics of SiC make its surface prone to fouling and icing. This not only shortens the service life of the material and reduces its utilization efficiency and braking performance but also poses potential safety hazards. These issues limit the broader application of SiC in various fields. Therefore, improving the surface properties of SiC materials through composite processing has become the key to broadening their applications. In this study, a laser-chemical composite processing method was developed to fabricate superhydrophobic SiC surface. First, regular hexagonal and smooth quadrilateral periodic micro-nanostructures were constructed on the surface of SiC materials by nanosecond laser ablation. Subsequently, superhydrophobic surfaces were successfully prepared by further silane-ethanol mixed solution modification and heat treatment. The surface morphology of superhydrophobic SiC materials was characterized by laser confocal microscopy and scanning electron microscopy, and the surface chemical composition was analyzed using energy-dispersive spectrometry and X-ray photoelectron spectroscopy. Furthermore, the influence of the surface structure and surface chemistry on wettability was clarified. Experimental results demonstrated that the surface roughness of the SiC material treated by the composite process increased significantly, forming a regular groove structure. As the laser scanning rate decreased, the depth of the surface grooves gradually increased. This reduction in air retention led to a decrease in the contact area between the water droplets and material surface, thereby affecting the surface wettability. Within a certain range, with the decreases in the laser scanning rate and scanning pitch, the surface wettability was improved, resulting in a composite Wenzel-Cassie state. The maximum contact angle of the material surface was 156.4°, and the minimum rolling angle was 1.3°. The O content on the surface of the untreated SiC material was 2.75%, and the functional groups of C-C and C-Si were the main components. After laser processing, the O content rapidly increased to 28.83%, resulting in a large number of C=O and Si-O-Si functional groups. After laser-chemical composite processing treatment, O accounted for 17.04% of the chemical components on the surface. Simultaneously, a large number of hydrophilic groups, such as C=O and C-O, were decomposed and broken. In addition, the distribution density of Si was notably different. Hydrophilic groups, such as C=O and C-O, were decomposed and fractured, resulting in the formation of a large number of hydrophobic functional groups, such as Si-O-Si. The surface of the superhydrophobic SiC material exhibited several enhanced functional properties. First, its surface could delay icing for over 250 s. Second, its corrosion resistance was significantly improved. Finally, it exhibited excellent self-cleaning performance. Moreover, compared with the smooth quadrilateral structure, the surface roughness of the regular hexagonal micro-nano structure was increased by more than 3 μm. The surface had a more obvious fence structure, and the ability of the grinding wheel to resist cyclic friction was increased by four times. The icing time was delayed by an additional 40 s, and it was completely frozen into ice droplets at 280 s. Therefore, the application requirements of the brake disc were satisfied. As demonstrated by the performance characterization experiments, the surface of the superhydrophobic SiC material exhibited excellent self-cleaning capability, corrosion resistance, icing resistance, and wear resistance. These properties indicate that the laser-chemical composite processing method can be used to prepare superhydrophobic SiC surfaces with stable performance. Ultimately, this process provides a theoretical and practical approach for the preparation of SiC material surfaces with desirable properties, thereby satisfying the application requirements of SiC brake pads. This study utilized fluorine-free chemical reagents, which are known for their low environmental impact and reduced costs. This approach is expected to further establish a foundation for the laser functionalization of SiC materials. It also has the potential to expand the scientific research and engineering applications of SiC materials in various fields.
  • Stress Inversion Method for Metal Coating Structure Under Ultrasonic Incidence Direction Control
    KE Qingdi, QIAN Zhimin, JIANG Shouzhi, LI Lubao
    China Surface Engineering. 2025, 38(4): 104-114. https://doi.org/10.11933/j.issn.1007-9289.20240820002
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    Metal-coated structures and their corresponding additive manufacturing technologies are widely used in industrial product manufacturing. In the formation of coating structures, heat sources such as laser and electron beams are primarily utilized to melt metal alloy powders or metal wires and stack them on the metal substrate material according to the design requirements. The high-energy input and metal liquid-solid phase transition during the formation process, results in a certain stress distribution inside the coating structure. To address the problem of complex stress fields inside a coating structure, as often observed in additive manufacturing processes, a stress inversion method is proposed for metal coating structures under ultrasonic incidence direction control. This method has good applicability for analyzing stress vectors, the corresponding distribution areas, and stress detection in the depth direction. The research mainly considered the following aspects: first, based on the theory of acoustic elasticity and stress Mohr circle theory, the relationship between ultrasonic longitudinal waves and internal stress distribution direction in the coating structure was analyzed, concluding that the influence of stress on ultrasonic waves can be regarded as the superposition of two orthogonal directions of stress. Subsequently, the stress distribution was orthogonally decomposed in the direction of ultrasonic propagation. Based on the above relationship, a general model was established for the ultrasonic signal stress characteristics, and the evolution law for ultrasonic signal propagation characteristics was examined under different stress fields inside the coating structure; second, the quantitative relationship between the stress parameters and ultrasonic longitudinal wave propagation velocity in the coating structure was analyzed, and an acoustic elastic coefficient for ultrasonically controlled angle propagation was proposed to express the relationship between different ultrasonic propagation directions and stress parameters. By controlling the ultrasonic incident direction, the complex stress inside the coating structure was inverted by varying the ultrasonic propagation time for different incident directions. A functional expression of the correlation between the ultrasonic signal characteristics and stress field state parameters was constructed, and the influence of the complex stress field on the ultrasonic propagation process was quantitatively analyzed. A stress inversion model for the coating structure was established, and the stress state parameters in the complex stress field were calculated based on the stress inversion model to determine the stress parameters inside the coating structure. Finally, specimens were prepared for the coating structure (C45E4-Ni60) using plasma spray welding additive manufacturing technology. The selected specimens were subjected to annealing heat treatment to reduce the influence of residual stress inside the specimen on subsequent test results. Ultrasonic signal analysis tests were conducted in the tensile / compressive stress loading environment at 25 ℃ A static loading test bench was used to load and simulate the 120 MPa tensile / compressive stress gradient generated inside the specimens. The ultrasonic incidence angles were adjusted to 0°, 15.7°, and 45°, to obtain the propagation time of the ultrasound in the coating specimens. The stress magnitude and direction inside the coating were calculated based on the stress inversion model of the coating structure and were compared with the actual loading stress parameters. The results show that by adjusting the ultrasound incidence direction thrice, the relative error between the stress values obtained by the stress inversion method and the actual loaded stress values can be as low as 6.15%, which verifies the effectiveness and accuracy of the proposed stress inversion method. The proposed ultrasonic stress detection method for coating structures can obtain the ultrasonic signal characteristics under different acoustic elastic distributions by controlling the direction of ultrasonic propagation and then inverting the stress magnitude and direction parameters in the coating structure. This method can be used for quality analysis, stress detection, and structural performance evaluation of coating structures in additive manufacturing.
  • Research Progress of Marine Antifouling Technologies
    JIANG Tao, LI Sining, CAO Hongbo, WANG Qianqian, HU Shengyue, XU Kangwei, CHEN Lingjie, XIE Shufeng, LI Long, WANG Zhe, TIAN Jiajia
    China Surface Engineering. 2025, 38(4): 115-131. https://doi.org/10.11933/j.issn.1007-9289.20241030001
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    Marine biofouling, defined as the attachment of marine microorganisms, algae, and barnacles to submerged surfaces, poses a significant threat to ships and marine equipment. Marine biofouling increases fluid resistance, reduces fuel efficiency, exacerbates structural damage, and shortens equipment lifespan. Various antifouling technologies have been developed to address these issues. Despite their effectiveness, traditional organic antifouling coatings, especially those relying on toxic biocides such as tributyltin, have been strictly restricted because of their detrimental impact on the environment. Therefore, the development of efficient, long-lasting, and environment-friendly antifouling technologies is of paramount importance. This study provides a comprehensive review of the development, mechanisms, and recent progress in antifouling technologies. It begins by introducing the formation process and impact of marine biofouling, with a particular focus on traditional organic antifouling coatings. These coatings inhibit biofouling by releasing biocides; however, their application is limited owing to environmental concerns, prompting researchers to seek alternative non-toxic or low-toxicity antifouling approaches. Subsequently, the research status of environment-friendly antifouling technologies, including fouling-release, fouling-resistant, and biomimetic antifouling technologies, is reviewed. Their antifouling mechanisms and characteristics are summarized, and the existing problems associated with each type of antifouling technology are discussed. Fouling-release coatings, which can release fouling organisms by flowing seawater owing to their intrinsically low surface energy characteristics, have been extensively studied. However, the drawbacks of fouling-release coatings, including poor antifouling ability under static conditions, poor mechanical robustness, and low adhesion strength, restrict their widespread use. In terms of fouling-resistant antifouling technologies, biofouling is inhibited by a hydration layer formed at the surface using hydrophilic materials. Although these technologies possess antifouling capabilities, they still face challenges in terms of durability, mechanical strength, and large-scale fabrication. Biomimetic antifouling technologies draw inspiration from the natural antifouling mechanisms of marine organisms, such as sharkskin microstructures, lubricating layers of pitcher plants, and natural antifouling agents. By using micro and nanostructures, liquid lubricating coatings, or natural antifouling components, these technologies can achieve non-toxic antifouling characteristics. These biomimetic antifouling technologies are both biocompatible and sustainable; however, further optimization is required for large-scale production and long-term durability. Additionally, the research status and application prospects of inorganic antifouling technologies with a focus on laser cladding and thermally sprayed antifouling coatings are summarized. Inorganic antifouling coatings fabricated by laser cladding or thermal spraying exhibit significantly superior mechanical robustness and adhesion strength to the substrate compared with organic antifouling coatings, thus being promising. The future development of inorganic antifouling coatings should focus on the fine design and regulation of their microstructures and properties. Based on a comprehensive review of the existing antifouling technologies, this study further dissects the key challenges and future development trends in antifouling research. The future development of antifouling technology should focus on the synergistic use of multiple antifouling techniques to achieve high efficiency, non-toxicity, environmental friendliness, long-term effectiveness, broad-spectrum protection, and the integration of corrosion and antifouling prevention. The development of novel intelligent antifouling technologies, multifunctional biomimetic antifouling methods, long-lasting green antifouling and anticorrosion solutions, and antifouling coatings with self-healing and self-cleaning capabilities is important for meeting diverse antifouling requirements in multiple marine areas and complex operational conditions. This study systematically categorizes antifouling technologies and provides a comprehensive overview of their mechanisms and limitations. It places particular emphasis on the development of environment-friendly and inorganic antifouling technologies, which hold the potential to address the current challenges in the antifouling field. By reviewing the advantages and drawbacks of the various approaches, this study offers valuable insights into the design and implementation of high-performance antifouling technologies. This study provides a solid theoretical foundation for future research.
  • Advances in the Characterization of Atmospheric Plasma Spraying Processes
    BAI Kaiwen, HUANG Yanfei, LIU Ming, ZHANG Zhiqiang, WANG Haidou, GAO Rui, ZHANG Hanbing
    China Surface Engineering. 2025, 38(4): 132-149. https://doi.org/10.11933/j.issn.1007-9289.20241126003
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    Atmospheric plasma spraying (APS) is one of the most extensively sprayed techniques,which can provide protective coatings that enhance the durability and performance of components from various industries, including manufacturing, aerospace, and power generation. This technology has gained prominence due to its versatility, high deposition rate, and cost-effectiveness, making it suitable for large-scale industrial applications. The APS can form a plasma jet through an electric arc between the cathode and the anode. The primary gases, typically are argon or nitrogen, and the secondary gases, such as hydrogen or helium, are ionized to create a high-temperature plasma plume. When the APS process beginning, the coating material, typically in powder form, is injected into the plasma jet. Here, the particles are subjected to intense heat, which causes them to melt or partially melt while simultaneously accelerating toward the substrate. Upon impact with the prepared substrate surface, the molten particles flatten and rapidly solidify, forming the coating. In this paper, the three sequentially interlocked phases of the APS process is presented: plasma jets, flying particles, and coating deposition. Research related to the characteristic properties of each phase and its evolution laws has been conducted by integrating experimental monitoring and numerical simulations. The generation of the plasma jet marks the beginning of the APS process. The plasma jet, formed by the ionization of gases, is characterized by extremely high temperatures. The temperature, velocity, and stability of the jet are predominantly influenced by the arc energy within the torch and the plasma ionization energy. These parameters are critical because they determine the thermal and kinetic energies imparted to powder particles. A stable and high-energy plasma jet ensures that the particles are adequately heated and accelerated, setting the basis for subsequent stages of the spraying process. As the plasma jet propels the powder particles forward, they transition to the flying-particle. During this phase, the particles are heated and accelerated by the jet. The temperature and velocity of these particles play pivotal roles in determining the coating quality. Higher particle temperatures and velocities enhance the ability of the particles to melt and flatten upon impact with the substrate, leading to improved coating density and bond strength. The physical properties of particles, such as their size and shape, also influence their interaction with the plasma jet. Research has demonstrated that particles with higher velocities are more effective at filling the gaps in coatings, contributing to a more uniform and dense coating. The interaction time between the particles and the jet is another critical factor; sufficient time is necessary for the particles to absorb adequate heat and reach the desired velocity. The final stage of the APS process is coating deposition, which involves the impact of molten particles on the substrate. The spread of these particles and their interactions with the substrate and the underlying layers are critical for the morphology, composition, and overall quality of the coating. The state of molten droplets at the time of impact, including their temperature and viscosity, determines how they spread and solidify. The kinetic energy of the particles upon impact also influences the degree of flattening and the resulting bond strength with the substrate. The nature of the contact between the molten droplets and the substrate, including factors such as surface roughness and cleanliness, affects adhesion and final coating properties. The study of atmospheric plasma spraying processes offers a profound understanding of the interplay between various parameters and the resulting coating characteristics. It is invaluable for optimizing the spraying process, ensuring consistent coating quality, and expanding the applications of APS in various industries. However, it still has challenges in current research. A significant challenge is to eliminate the jet fluctuations, which can affect the stability and uniformity of the coatings. Thus, the further research is required to develop more stable plasma jets and mitigate the adverse effects of these fluctuations. Additionally, the study of multiparticle stacking and lapping remains an area requiring further exploration. Moreover, understanding the complex interactions between multiple particles during deposition can lead to better control of the coating microstructure and improved its performance. Future research should focus on advanced diagnostic techniques and numerical simulations to unravel these complexities and lay a basis for more sophisticated and efficient APS technology.
  • Progress on the Tribological Properties of MAX-phase Carbide Ceramics over a Wide Temperature Range
    JIA Bingsen, XU Wenju, LI Jingfeng, LIU Xiaohong, JI Li, LI Hongxuan, WANG Kunjie
    China Surface Engineering. 2025, 38(4): 150-165. https://doi.org/10.11933/j.issn.1007-9289.20240326001
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    MAX-phase carbide ceramics have emerged as leading candidates in the field of high-temperature structural materials owing to their unique combination of properties. These materials not only exhibit the high-temperature stability, corrosion resistance, and oxidation resistance typical of ceramics, but also possess the toughness and thermal conductivity characteristic of metals. In extreme environments, MAX-phase ceramics are particularly noteworthy for their wide-temperature-range lubrication capabilities, enabling them to maintain stable lubrication performance across diverse temperature conditions—an essential feature for addressing lubrication and wear challenges in critical moving parts. In terms of synthesis, MAX-phase materials are usually prepared by high-temperature solid-state reactions, in which the M-site, A-site, and X-site elements are ball-milled and mixed, and then treated at high temperatures to form the target MAX phase. Additionally, physical vapor deposition techniques are widely used to synthesize MAX phases, allowing atomic-level mixing and significantly lowering the synthesis temperature. These advancements in processing technology have laid the groundwork for the industrial-scale application of MAX-phase materials. With regard to wide-temperature-range lubrication research, the self-lubricating mechanism of MAX-phase ceramics is attributed to the diffusion of M-site and A-site elements to the material surface under the influence of friction and heat. These elements then react with environmental oxygen to form a stable oxide lubrication film, effectively reducing both the coefficient of friction and wear rate. Studies have shown that the composition of MAX-phase ceramic composites, operating conditions, and processing methods significantly affect their tribological behavior.In high-temperature environments, the evolution of elemental composition and microstructure, and their correlation with lubrication behavior, have been extensively investigated. For instance, Ti3SiC2 demonstrates excellent oxidation resistance at elevated temperatures, owing to the formation of Si-containing oxides. Similarly, Al-based MAX phases such as Ti2AlC and Cr2AlC show superior antioxidation performance owing to the formation of a continuous, dense Al2O3 layer on their surfaces. In terms of synergistic lubrication and composite systems, MAX / metal and MAX / ceramic composites exhibit outstanding tribological performance. Effective wettability between constituent materials is essential for forming dense, homogeneous composites. For example, Ti3AlC2 / TiB2 composites display superior high-temperature strength and lubricity, attributed to the rapid oxidation of TiB2 during high-temperature friction, forming a smooth and continuous B2O3-containing lubricating film. Regarding the design of novel high-entropy MAX-phase ceramics and the associated challenges of multi-element solid solutions, high entropy has been shown to enhance the functional properties of MAX phases for applications in photovoltaics, catalysis, magnetism, and energy storage. High-entropy MAX phases introduce localized chemical fluctuations (LCFs), increasing lattice strain, which strengthens resistance to dislocation slip and results in a compressive yield strength exceeding 500 MPa at elevated temperatures. Moreover, LCFs facilitate cross-slip and the formation of stacking faults during deformation, suppressing strain localization and promoting uniform plastic deformation at both room and high temperatures. In conclusion, research on MAX-phase carbide ceramics has advanced both in theory and application. Their superior high-temperature tribological properties and wide-temperature-range lubrication behavior offer new insights and a solid theoretical foundation for the development of next-generation adaptive lubrication materials. As research continues to deepen, MAX-phase carbide ceramics are poised to play an increasingly significant role in the field of high-temperature structural applications.
  • Progress of Cold Spray Coating on the Surface of Zirconium Alloy Tubes for Accident Tolerant Fuels
    FU Shuo, XU Aijun, LUO Jie, ZHANG Yuanying, XU Zhuoqing, MA Xin, XU Yaxin, HUANG Chunjie, LI Wenya
    China Surface Engineering. 2025, 38(4): 166-178. https://doi.org/10.11933/j.issn.1007-9289.20241031006
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    Following the accidents at the Fukushima Daiichi Nuclear Power Station, an increasing number of countries have conducted research on zirconium alloy tube coatings for accident-tolerant fuel in light-water reactors. Among the various coating preparation techniques, cold spraying has emerged as a promising method for preparing zirconium alloy tube coatings, due to its low heat input, high deposition efficiency, and dense microstructure. This paper reviews research on cold-spray coating preparation for zirconium alloy tubes, focusing on the selection of materials for protective coatings on zirconium alloys, high-temperature oxidation resistance, and irradiation performance under loss-of-coolant accident conditions. First, the bonding mechanisms and microstructures of cold-sprayed chromium (Cr) coatings on Zr substrates are investigated. Cr coatings exhibit exceptional high-temperature oxidation and irradiation resistance due to their low neutron absorption cross-sections and stable high-temperature oxides. The factors influencing the deposition characteristics, such as powder preparation methods and pretreatment techniques, are discussed. The experimental results indicate that optimized Cr powders and post-treatments (e.g., annealing) significantly enhance coating density, reduce residual stress, and improve adhesion strength. The oxidation behavior of Cr coatings prepared by cold spraying was investigated under high-temperature steam conditions. However, interdiffusion between the Zr substrate and Cr coating affects the protective properties of the coating. To address this, an anti-diffusion layer, such as Nb or Mo coating, was successfully formed on the Zr substrate by cold spraying. Cr coatings were also successfully deposited on the anti-diffusion layer, resulting in significantly improved coating properties. Following the discussion of Cr coatings, the performance of FeCrAl coatings is also summarized. The excellent high-temperature stability and irradiation resistance of these coatings make them suitable for Zr tube applications. Under high-temperature and irradiation conditions, the surface of the FeCrAl coating evolves into a ZrC layer as the experiment progresses. This unique structure imparts self-repairing capability to the coating in irradiation environments. The formation of an Al2O3 layer on the coating surface during high-temperature exposure significantly enhances oxidation resistance. However, FeCrAl coatings exhibit interdiffusion with the Zr substrate, leading to the formation of low-melting-point eutectic phases that influence the protective properties of the coating. To address these problems, diffusion barrier layers such as Mo or Nb were deposited on the Zr substrate. These layers delay the interdiffusion process between the FeCrAl coatings and the Zr substrate, thereby extending the service life of the coatings. Additionally, MAX-phase coatings have shown potential for use in high-temperature oxidation and irradiation environments. However, the high porosity of these coatings compromises their protective properties. Furthermore, irradiation induces the formation of an amorphous layer and a disordered laminar structure, causing lattice damage and cracking in the MAX coatings. Therefore, further investigation is required on MAX-phase coatings prepared by cold spraying to maximize the protective benefits of the MAX phase. Finally, the research progress and challenges of zirconium alloy cold-spray coatings are reviewed, and future development directions are discussed. In summary, the progress in cold-sprayed coatings for zirconium alloy cladding tubes offers a comprehensive overview of their role in enhancing nuclear reactor safety. By addressing these technical challenges and exploring innovative solutions, cold spraying has the potential to advance the development of Zr alloy tube coatings, improve resistance to extreme operating conditions, and ensure the safe operation of light-water reactors.
  • Research Status and Application of Fe-based Amorphous Coatings
    HU Mingchao, ZHAO Yuncai, WANG Huipeng, HUANG Yanfei, XING Zhiguo, ZHU Hefa, GUO Weiling, WANG Haidou
    China Surface Engineering. 2025, 38(4): 179-197. https://doi.org/10.11933/j.issn.1007-9289.20240716002
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    Fe-based amorphous alloys have attracted the attention of researchers due to their excellent mechanical and soft magnetic properties, wear resistance, and corrosion resistance. The short-range order and long-range disorder characteristics of the amorphous structure play important roles. However, the room-temperature brittleness and size limitations of Fe-based amorphous alloys seriously limit their practical applications in surface protection. By overcoming the room-temperature brittleness and size limitations of amorphous alloys, Fe-based amorphous coatings can be prepared using coating technologies such as thermal spraying and laser cladding. These coatings retain high hardness, wear resistance, and corrosion resistance, enabling their application in surface protection of parts. Therefore, this study systematically summarizes the current research status of Fe-based amorphous coatings. In this paper, the recent research progress on Fe-based amorphous coatings is discussed from four aspects: coating materials, coating preparation technologies, wear and corrosion resistance, and practical applications. The results showed that among Fe-based amorphous coating materials, the "Fe-ETM-LTM-M" type Fe-based amorphous alloy powder has the highest glass-forming ability. The Fe-based amorphous alloy powder prepared by the atomization method has a smooth surface and a moderate particle size range, making it most suitable for the preparation of Fe-based amorphous coatings. The coating prepared by thermal spraying exhibited a uniform composition and dense structure. Coatings prepared using laser cladding technology can form metallurgical bonds with the substrate, resulting in high bonding strength. In addition, coating preparation techniques such as detonation spraying, cold spraying, and magnetron sputtering have also been used to produce Fe-based amorphous coatings. Therefore, thermal spraying and laser cladding have become the two most commonly used technologies for preparing Fe-based amorphous coatings, and the performance of these coatings can be improved through appropriate technical adjustments or the addition of auxiliary fields. Technical adjustments can be achieved by modifying the structure of the spraying device to obtain a higher heat source temperature or increase the particle flight speed. The addition of an auxiliary field—such as coupling an ultrasonic vibration field or an electromagnetic field outside the coating preparation device—can reduce the number of cracks in the prepared Fe-based amorphous coating. During the coating preparation process, factors such as element composition, the addition of reinforcing phases, and pre / post-treatment procedures contribute to improving the wear and corrosion resistance of Fe-based amorphous coatings. For example, low-temperature cyclic treatment can induce structural relaxation in the coating without causing recrystallization, while the regulation of elemental composition can enhance the stability of the passivation film formed on the coating surface. Moreover, the addition of hard phases—such as WC—effectively blocks the propagation of shear bands and enhances the wear resistance of Fe-based amorphous coatings. Pores not only serve as primary channels for corrosive substances to penetrate the coating but also act as the initial sites of surface damage under friction and wear. Sealing treatments can effectively reduce the number of pores in Fe-based amorphous coatings, thereby expanding their application prospects under complex working conditions. Fe-based amorphous coatings have played a key role in the military and nuclear industries, power equipment protection, and other fields, thanks to performance enhancements developed by scientific and technical personnel. These four aspects illustrate the performance improvements and current practical applications of Fe-based amorphous coatings from different perspectives, providing a valuable reference for researchers and engineers involved in their development.
  • Variation in the Three-dimensional Metal Magnetic Memory Signals of Ferromagnetic Materials under Tensile Stress
    WANG Huipeng, LI Haihang, SHI Jialong, DONG Lihong, WANG Haidou, LIU Huizhong
    China Surface Engineering. 2025, 38(4): 198-207. https://doi.org/10.11933/j.issn.1007-9289.20240417001
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    Metal magnetic memory testing (MMMT) is a promising non-destructive testing (NDT) method for damage diagnosis of ferromagnetic materials because it offers potential for early damage (such as stress concentration) detection. The key to quantifying the damage degree using MMMT is accurately and comprehensively determining the magnitude and distribution of the MMMT signals. Current research studies on MMMT focus on one- and two-dimensional MMMT signals, while the magnetic field is a three-dimensional vector field. In addition, the MMMT signals are weak and can be easily disturbed by the environmental magnetic field during the detection process. Thus, it is necessary to reveal the variation of the three-dimensional MMMT signals during the static tensile tests. The magnetic domain is the inner magnetization region of ferromagnetic materials. The direction of the magnetic moment of the domain is randomly distributed when no external magnetic field is applied, and the material as a whole is paramagnetic. However, the magnetic moments of the domains would be reoriented when the material is subjected to applied stress, which results in a macroscopic magnetization effect. Therefore, static tensile tests were carried out on standard specimens made of a base metal and weldment of ferromagnetic material, and the properties of the three-dimensional MMMT signals were analyzed systematically by feature extraction, microscopic magnetic domain theory, and magnetic charge theory. When the specimen was loaded to the preset load at a constant loading rate, the specimen was held for 30 s, and then, it was removed from the gripers and placed on a non-magnetic three-dimensional electrically controlled displacement platform along the south-north direction. The MMMT signals of the specimen were collected using a 3D Gaussmeter with a resolution of 0.1 μT. The gaussmeter was fitted on the non-magnetic displacement platform, which could move automatically to avoid interference from external magnetic fields and manual operation errors. When axial tensile stress was applied to the base metal specimens, the Bx and By signals were horizontal lines, and the Bz signal was an inclined straight line. The Bx and By signals moved upward, the Bz signal rotated counterclockwise with increasing applied stress during the elastic deformation stage, and the Bx and By signals moved downward and the Bz signal rotated clockwise in the plastic deformation stage. The mean and peak values of the Bx and By signals as well as the slope of the Bz signal showed good agreement with the applied tensile stress. For the weldment specimens, a peak of the Bx signal and abnormal peaks of the Bz signal were observed at the weld joint. The mean and peak values of the Bx signal and slope of the Bz signal increased linearly with the applied tensile stress. The By signal showed no obvious abnormality at the weld joint and the amplitude was relatively small, the By signal could not be used for the stress estimation of the weldment. Based on the characteristic variation of the three-dimensional metal magnetic memory testing signals and the magnetic domain, theory a physical model between the metal magnetic memory testing signals and the applied tensile stresses with the magnetic charge was proposed. Thus, using this proposed method, a simpler and more effective calculation of the strength of the metal magnetic memory testing signal and the magnetic charge under the effect of stress can be conducted.
  • Study on the Effect of Nitride Interlayer on the Structure and Tribological Properties of Carbon Films
    ZHAO Yanchun, HE Ruifang, GAO Kaixiong, ZHANG Bin, WANG Xin, XU Chunling
    China Surface Engineering. 2025, 38(4): 208-220. https://doi.org/10.11933/j.issn.1007-9289.20240422001
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    Diamond-like carbon (DLC) film are solid lubricating materials composed of sp2 / sp3 carbon hybrids. They have the advantages of high hardness, wear resistance, long life, good chemical stability, easy access to atomically smooth surfaces, and an adjustable composition and structure. They can achieve low friction or even super-lubricity (friction factor <0.01) under atmospheric and heavy load conditions and are expected to be applied to traditional aero-engine systems. However, the high internal stress in DLC films makes it subjected to failure by film delamination under complex loading conditions during friction, which restrict its application in aero-engines and the service life of aviation equipment. To address these issues, current studies have been undertaken by adopting doping, multi-layer structures, and nitriding / coating composite surface treatments, which improve the film performance on one hand but may undermine the overall performance of film / substrate. For instance, doping reduces the internal stress while degrading mechanical properties of the DLC, whereas high-temperature nitriding degrades the performance of aero-engine gear steel substrates. A proper interlayer structure design can improve the film / substrate adhesion and bridging the gaps in the mechanical properties between the substrate and film, which would alleviate film internal stress and enhance the overall tribological performance. To provide a guideline for the application of solid lubricating films in aviation equipment, we investigate the effect of different interlayers on tribological properties of carbon films and ion-infiltrated composite carbon films in this study. A series of hydrogenated carbon films with multi-layer structures are prepared on a Si substrate using medium-frequency magnetron sputtering. The structure, surface morphology, and mechanical and tribological properties of TiSi / TiSiN / TiSiC / a-C:H films are evaluated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Raman spectroscopy, nanoindentation, surface profilometry, and friction testing. The results show that the deposition rate of the hydrogenated carbon films increases with an increase in the nitrogen content in the interlayer. The optimal hydrogenated carbon film has the highest hardness of 15.50 GPa with lowest residual stress (-0.5 GPa), strongest binding force (13.4 N), the lowest wear rates of 1.8×10-8 mm3 / (N·m). Compared with the nitrogen-free DLC, the nitrogen doped samples have higher hardness and good anti-friction and wear resistance, indicating that the addition of the intermediate TiSiN layer can improve the mechanical and tribological properties of the a-C:H film. Microstructure analysis show that TiSi / TiSiN / TiSiC / a-C:H film promote the graphitization process from sp3 to sp2 during friction, which is beneficial for reducing friction and the wear rate. These results provide technical basis for preparation of wear-resistant DLC multi-layer films on aviation gear steel substrates.
  • Study on the Influence of DLC Film on the Tribological and Mechanical Properties of A100 Steel
    DU Juan, GAO Shenyuan, YU Wenjun, FAN Xiaoqiang, ZHU Minhao
    China Surface Engineering. 2025, 38(4): 221-232. https://doi.org/10.11933/j.issn.1007-9289.20240529002
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    As a representative high-tech industry, the aerospace industry has become a new platform for global national defense construction and economic growth. It has an extremely important strategic development status, which offers a broader space and unlimited possibilities for the future high-quality development of human society. Among aerospace components, the operating aircraft landing gear must absorb and dissipate the impact energy of the aircraft during landing and taxiing, thus retarding impact against the ground. Aircraft landing gear and other key components are typically operated under harsh environmental conditions of reciprocating friction. Owing to the rapid development of modern industry, high-strength, high-toughness, and excellent wear-resistant steel materials have received widespread attention; however, under high-stress and high-wear operating conditions, severe friction wear remains. Surface-modification technologies, such as nitriding, electroplating, shot peening, and solid lubrication films, are important to improve the antiwear performance of metal matrices. Additionally, during the operation of major machinery and equipment, the addition of grease to reduce frictional wear is pivotal. In this study, diamond like carbon (DLC) films with WC as the transition layer are deposited on A100 steel substrates via magnetron sputtering, whereas strong and dense DLC coatings with good bonding are successfully prepared. Experimental results show that the DLC film effectively reduced the coefficient of friction and wear rate of the A100 steel substrate under both graphene grease lubrication and dry friction. During dry friction, the wear rate decreased from 14.38 × 10-6 to 0.47 × 10-6 mm3 / (N·m), which significantly improved the wear resistance. The mechanical properties of A100-DLC composites are further tested, and the results show that the composites exhibit better fatigue resistance and bending mechanical properties than those of A100 steel. This finding suggests that the introduction of DLC films not only improves the wear resistance of the substrate but also enhances its overall mechanical properties, thereby increasing the service life of the metal substrate. Additionally, the lubrication effect under solid-grease composite conditions is investigated, whereas the effects of solid lubricating coatings and liquid lubricants have been widely reported. Nonetheless, both methods demonstrate their own advantages and disadvantages. Therefore, combining solid and liquid lubricating materials may be considered in the future to minimize their individual disadvantages through synergistic effects. Results show a good synergistic effect between DLC film and graphene grease, and that their joint action would offer greater friction reduction and antiwear effect. This solid-grease composite lubrication further enhances the wear resistance of the metal matrix, thus providing strong support for practical applications. Finally, the anti-fatigue and synergistic lubrication effects of the DLC film and graphene grease are investigated via bending, fatigue, and rolling contact fatigue tests. The DLC film improved the fatigue strength and wear resistance of the A100 substrate, whereas the graphene grease showed excellent friction reduction. Meanwhile, the solid-grease composite afforded an even better friction-reduction and antiwear effect. In summary, graphene oxide is modified using a titanate coupling agent and stably dispersed in grease, thus resulting in high-performance functionalized graphene grease. WC is selected as the transition layer, whereas enhanced DLC films with a high bonding force between them and the A100 matrix are prepared via magnetron sputtering. The DLC-based solid-grease composite lubrication coating is prepared by combining the DLC film with graphene grease, which exhibits excellent physicochemical and tribological properties, thereby resulting in high hardness and mechanical strength. This approach effectively improves the tribological and mechanical properties of the metal matrix. Finally, this study benefits the aerospace field significantly and is expected to provide new ideas for improving the wear reduction, antiwear, and mechanical properties of high-strength and high-toughness materials under complex and harsh operating conditions.
  • Preferred Orientation Tuning and Performance of AlN Films Prepared by Pulsed DC Magnetron Sputtering on Invar 36 Surfaces
    WU Yi, TANG Guoliang, LI Wenju, XIAO Shu
    China Surface Engineering. 2025, 38(4): 233-243. https://doi.org/10.11933/j.issn.1007-9289.20231129001
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    The widespread adoption of organic light-emitting diode (OLED) flexible display technology in modern electronics has necessitated improvements in packaging techniques to enhance the durability and functionality of these devices. A critical component of this advancement is the use of high-quality chemical vapor deposition (CVD) masks, which are predominantly fabricated from Invar 36 alloys. This type of material is selected owing to its exceptionally low thermal expansion coefficient of 1.8×10-6 / ℃, which ensures superior dimensional stability under varying thermal conditions. Despite the advantageous properties of Invar 36 alloys, the CVD masks manufactured using these materials encounter significant challenges during device fabrication. These challenges include arcing and plasma etching, which can degrade the mask and affect the overall quality of the OLED display. To mitigate these issues, protective films are applied to CVD masks. Alumina (Al2O3) is commonly used because of its excellent insulating properties and corrosion resistance. However, the substantial difference in the thermal expansion coefficients of Al2O3 (7.85×10-6 / ℃) and Invar 36 alloys can lead to thermal stress, which poses a serious compatibility problem. Aluminum nitride (AlN) has emerged as a promising alternative to protective films owing to its high hardness, remarkable thermal conductivity, and outstanding insulating characteristics. Its thermal expansion coefficient of 4.3×10-6 / ℃ matches more closely with that of Invar 36 alloys, reducing the risk of thermal stress. Moreover, the performance of the AlN films is closely linked to their crystallographic orientations. The a-axis (100) orientation is known for its superior resistance to fluoride-ion corrosion, which is particularly relevant in environments where corrosive elements are present. Conversely, the c-axis (002) orientation significantly enhances the insulating and mechanical properties of the films, making them suitable for applications requiring high dielectric strength and durability. Reactive magnetron sputtering was used to deposit AlN films onto Invar substrates. The deposition process was fine-tuned using a pulsed direct-current power with the following parameters: 500 watts, 40% duty cycle, and a frequency of 20 kHz. Substrate rotation speeds of 0, 5, and 20 r/min were selected to explore the effect on the orientation of the AlN films during growth and investigate their properties. Advanced characterization techniques were employed to analyze the AlN films. X-ray diffraction (XRD) was used to determine the crystal structure, field-emission scanning electron microscopy (FESEM) was used to provide insight into the morphology, and energy-dispersive X-ray spectroscopy (EDS) was used to assess the elemental composition. Increasing the substrate rotation speed significantly inhibited the growth of the (002) orientation, which in turn affected the grain size within the films. To evaluate the electrical properties of the films, surface resistivity and dielectric strength tests were performed using a concentric heavy hammer electrode and dielectric strength tester, respectively. In addition, potentiodynamic polarization tests were performed using an electrochemical workstation generated Tafel curves, which were instrumental in determining the corrosion potential and current density of the films. The results indicated that the (002) oriented films exhibited significantly higher surface resistivity (1.3×1014 Ω), whereas the (100) oriented films exhibited enhanced resistance to fluoride-ion corrosion with a lower corrosion current density of 1.62×10-9 A / cm2. A clear correlation between the crystallographic orientation of the AlN films and their respective properties was established, highlighting the substrate rotation speed as a critical factor in determining the preferred growth orientation. Further investigations of the energy and particle diffusion aspects of the preferred orientation during growth will contribute to a deeper understanding of the kinetic factors that influence orientation changes. The comprehensive insights gained from this study into the effects of rotational kinetic energy on AlN film growth provide a solid theoretical basis for the controlled preparation of AlN films on Invar surfaces. The minimal rotational kinetic energy at rest and low velocity facilitated the orderly stacking of adsorbed atoms on the substrate, while providing sufficient surface diffusion energy to promote the formation of the (002) orientation. Increasing the rotational speed resulted in a higher rotational kinetic energy, causing the adsorbed atoms to disperse from their original deposition sites and acquire tangential energy from the substrate surface. This counteracted the surface diffusion energy, influenced the rearrangement process, and led to the formation of the (100) orientation. Subsequent property tests on different orientations demonstrated the distinct advantages associated with each orientation after considering the impact of the rotational speed on the AlN orientation. These findings are vital for the development of advanced manufacturing processes and improving the longevity and performance of OLED displays, ensuring that these cutting-edge technologies can satisfy the rigorous demands of contemporary electronic devices.
  • Preparation and Anti-icing Characteristics of Durable Superhydrophobic Composite Coatings of Nano-silica / Fluorocarbon Resin
    SHI Er, LIU Bowen, ZHAO Bin, JIANG Changwei, ZHOU Wulin
    China Surface Engineering. 2025, 38(4): 244-254. https://doi.org/10.11933/j.issn.1007-9289.20240903003
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    Ice accretion on wind turbine blades is a significant issue that can negatively affect the economic efficiency and operational stability of wind farms. Ice on blades can reduce aerodynamic performance, increase mechanical load, and lead to potential operational downtime, diminishing the overall power generation capacity of wind turbines. Although existing superhydrophobic coatings have been explored for blade de-icing, they often suffered from complex preparation processes and limited durability. To address these challenges, this study introduced a novel two-step spraying method for preparing superhydrophobic composite coatings on glass fiber-reinforced epoxy resin substrates, thereby achieving a maximum contact angle of 156.1°. The process began with the spraying of a hydrophobicfluorocarbon resin as an adhesive layer, followed by the spraying of silica nanoparticle dispersion modified with a γ-GPTMS coupling agent on to the semi-cured adhesive layer. This dual-layer approach enables silica nanoparticles to uniformly deposit within the fluorocarbon resin through free deposition, thereby ensuring an even distribution of nanoparticles at the surface and within the coating. This structure promoted consistency between the internal and surface layers of the coating. Even if the surface of the coating was damaged during operation, the underlying hydrophobic particles continued to maintain low surface energy and roughness, preserving the superhydrophobic properties of the coating. A comprehensive characterization of the coating was conducted using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), contact angle measurements, and CCD imaging. The SEM analysis revealed that the surface of the composite coating exhibited a typical superhydrophobic micro-nano structure, with evenly distributed fluorine, silicon, and oxygen elements. No element segregation was observed, which indicated uniform performance across the coating. The durability and wear resistance of the coating were evaluated using the ISO 8251-2018 standard, employing a reciprocating wear test. The coating was subjected to abrasion with a 400-grit sandpaper under a 500 g load, with periodic friction cycles of 20 cm. After 160 wear cycles, the contact angle of the coating remained at 152.9°, with a rolling angle of 8.7°. The decrease in contact angle was minimal, with only a 3.2° drop from the initial 156.1°, indicating an excellent abrasion resistance and robustness under mechanical stress. The anti-icing performance of the superhydrophobic composite coating was tested under various conditions. At -12 °C, the ice adhesion strength of the coated surface was 97.6 kPa, which represented a significant reduction of 72.1% compared to the uncoated surface, which had an adhesion strength of 349.5 kPa. At -6 °C, the average ice adhesion strength on the coated surface was 87.2 kPa, reflecting a reduction of 72.8% compared to the uncoated surface (320.1 kPa). Moreover, the icing delay time at -12 °C was extended to 2413 s, thereby marking an increase of 574% compared to the uncoated surface. Under simulated freezing rain conditions at wind speeds of 4 m / s and 8 m / s, the final ice accumulation on the coated surface was significantly lower than that on the uncoated surface. At 4 m / s, the uncoated surface accumulated 8.28 g of ice, whereas the superhydrophobic coating accumulated only 3.58 g, resulting in a reduction rate of 56.78%. At 8 m / s, the uncoated surface accumulated 10.19 g of ice, while the coated surface accumulated 4.63 g, with a reduction rate of 54.58%. The two-step spraying method used in this study has been proven to be an effective strategy to enhance the anti-icing performance and durability of superhydrophobic coatings. The proposed composite coating provides a promising solution to improve the anti-icing capabilities of wind turbine blades, addressing both operational and economic challenges in wind energy production. This innovative coating method holds potential for broad applications in the wind energy sector, particularly in regions prone to severe icing conditions.
  • Preparation and Property of Photothermal Superhydrophobic Coating Based on Fe3O4@SiO2 Composite Particles
    XIE Yulong, LI Li, LUO Chaoyueling, XIE Yi, CHEN Junwu
    China Surface Engineering. 2025, 38(4): 255-265. https://doi.org/10.11933/j.issn.1007-9289.20240805001
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    Icing poses a critical safety threat to electrical power systems under harsh weather conditions where the ice accumulation on transmission lines and equipment can lead to mechanical failure, power outages, and increased maintenance costs. Although traditional superhydrophobic coatings have demonstrated effectiveness in passive anti-icing applications, their performance in active de-icing remains inadequate, particularly after ice formation. To address these limitations, this study proposes a novel photothermal superhydrophobic coating that incorporates Fe₃O₄@SiO₂ composite particles to enhance both anti-icing and de-icing capabilities. This innovative coating combines passive water-repellence with active solar-driven de-icing, thereby offering a comprehensive solution to icing challenges in outdoor power systems. The coating was developed by integrating Fe₃O₄ nanoparticles, which is a cost-effective photothermal material, into a modified SiO₂ dispersion. The resulting Fe₃O₄@SiO₂ composite particles were applied on to pre-treated glass substrates via spray coating or dip coating, followed by curing at 80 °C. The Fe₃O₄ nanoparticles were selected for their strong solar absorption and efficient light-to-heat conversion, which enabled rapid de-icing under sunlight. The low-temperature preparation process ensures scalability and economic feasibility for industrial applications. The performance of the coating was evaluated systematically using a series of tests. The measurements of the water contact angle (WCA) and rolling angle (RA) confirmed its superhydrophobic nature, with a WCA exceeding 158° and an RA below 3°. These results indicate excellent water-repellence, which reduces the likelihood of ice nucleation on the surface. Under no-light conditions, the coating extended the time required for ice formation by 2.71 to 8.17 times compared to that when using traditional materials. In the presence of sunlight, the coating completely prevented ice formation for up to 1,000 s. Photothermal de-icing tests further highlighted the efficacy of the coating, with de-icing times reduced by up to 65.83%, thereby outperforming conventional anti-icing coatings. Durability tests under extreme conditions validated the robustness of the coating for long-term outdoor use. The superhydrophobic and anti-icing properties were retained after thermal cycling, mechanical abrasion, and multiple icing-de-icing cycles, demonstrating excellent resistance to environmental degradation. In addition, prolonged UV exposure did not impair the structural integrity or functional performance of the coating. These results underscore the potential of the coating for deployment in harsh weather environments. The innovation of this study lies in the strategic use of Fe₃O₄ nanoparticles as a photothermal agent. Compared to expensive alternatives such as graphene and carbon nanotubes, Fe₃O₄ is not only cost-effective but also readily available, which makes it an attractive choice for large-scale applications. Furthermore, the simplified preparation process eliminates the need for complex microstructure design or high-temperature curing, addressing common barriers to the industrial adoption of advanced coatings. The Fe₃O₄@SiO₂ composite coating offers a unique combination of passive and active ice mitigation. The high contact angle and low rolling angle ensure that water droplets easily roll off the surface, thereby minimizing ice adhesion. Simultaneously, the photothermal effect actively melts existing ice, facilitating de-icing even under challenging conditions. This dual functionality significantly enhances operational reliability for power systems, reducing maintenance downtime and the risk of equipment failure caused by icing. In addition to its functional performance, the coating demonstrates strong mechanical and chemical stabilities, which are critical for enduring repeated exposure to environmental stressors. The ability to maintain performance after repeated abrasion and thermal cycling positions it as a durable solution for real-world applications. In conclusion, the Fe₃O₄@SiO₂ photothermal superhydrophobic coating developed in this study represents a significant advancement in anti-icing and de-icing technologies. This research provides a practical approach to mitigating icing issues in outdoor electrical power systems by addressing the limitations of traditional coatings and introducing a cost-effective, scalable, and durable solution. The excellent performance of the coating under both passive and active conditions, combined with its robustness and economic feasibility, makes it a promising candidate for widespread implementation in regions prone to severe icing. Future work focuses on optimizing the preparation process of the coating and exploring its potential applications in other industries, such as transportation and renewable energy systems, where icing poses similar challenges.
  • Process Optimization of YSZ / GZO Coatings by Plasma Spray-physical Vapor Deposition
    LI Xinhui, HE Qing, WANG Shixing, YOU Xiaoming, ZOU Han, ZHAO Qian
    China Surface Engineering. 2025, 38(4): 266-279. https://doi.org/10.11933/j.issn.1007-9289.20240604003
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    Thermal barrier coating preparation technology by using plasma spray-physical vapor deposition (PS-PVD) can realize the aid in controlling the gas-liquid-solid three-phase composite deposition, offering significant potential for preparing high insulation and long life cylindrical thermal barrier coatings. Further, the microstructural and interfacial structure of PS-PVD coating are directly related to the characteristics of high heat insulation and long life of PS-PVD coating, which can be realized by optimizing the process parameters of PS-PVD coating. The gas-liquid-solid three-phase content and distribution in the jet at the position of the substrate during the coating deposition process are different because of the numerous and complex process parameters of PS-PVD and the interaction between the parameters. This results in obvious differences in the microstructure and properties of the deposited coating. Therefore, the traditional single variable experiment approach increases the costs and frequency of experiments. Based on Taguchi's experimental design, this study considers spraying current, scan distance, and powder feed rate as influencing factors and coating characteristics and thermal shock life as response values for analyzing the main effect diagram. Further, variance analysis is used to determine the interaction of the mean value of each response value. The results indicate that the effects of the process parameters on the fine equiaxed grains thickness and intercolumnar gap are the same. The significant effects on the fine equiaxed grains thickness and intercolumnar gap are powder feed rate > scan step > spraying current. The significant effects on the column diameter are scan step > spraying current > powder feed rate. This provides a technical basis for the controllable preparation of YSZ / GZO composite coatings using the PS-PVD process. The main factor affecting the thermal shock life of the coating is the interface structure control of the bond layer / ceramic layer. The preparation of continuous and dense thermal grown oxide (TGO) interface coating samples exhibit characteristics of long lifetimes. The morphology and thickness of TGO at the interface between the bond layer and ceramic layer of the thermal barrier coating are obviously different under different processes because of the plasma jet temperature gradient and the heat flux input received by the sample surface under different process conditions. The coating shows typical columnar crystal structures of PS-PVD prepared under this process parameters, and the columnar crystal growth is continuous at the YSZ / GZO coating interface, which provides the technical basis for the controllable preparation of YSZ / GZO coating microstructure using the PS-PVD process. When other parameters are considered, the significant effects on YSZ / GZO coating life are scan step > spraying current > powder feed rate. In this case, the preferred process parameters are a scan step of 200 mm, spraying current of 2200 A, and powder feed rate of 10 g / min. The thermal shock life of the gas at 1350 °C reaches 3062 times. Taguchi's experimental design can effectively improve the accuracy and reliability of experimental data and significantly reduce the research and development costs and experiment cycle. In this paper, Taguchi's experimental design method was used for systematically studying the microstructure changes and thermal shock life of YSZ / GZO composite coatings under different PS-PVD process parameters. The interaction law of each process parameter was analyzed, and the preparation process parameters of PS-PVD coating were optimized. PS-PVD YSZ / GZO composite coatings with a high performance and long lifetimes were prepared. The micro-structure control and controllable preparation method for the composite coating were established, providing a technical reserve for preparing high-performance PS-PVD YSZ / GZO composite coatings and its engineering applications.
  • Corrosion Inhibition Properties of Betaine Derivatives Combined with Na2SiO3 on Aluminum Alloy Surface in Alkaline Medium
    AO Ran, YUAN Chunhua, HE Wei, JIA Yan, CHEN Bo
    China Surface Engineering. 2025, 38(4): 280-293. https://doi.org/10.11933/j.issn.1007-9289.20240112003
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    Aluminum alloys are widely used in various fields owing to their excellent performance. Aluminum alloys exhibit high corrosion resistance, mainly because their surface can form a dense oxide film; however, its oxide film is only stable in a medium with pH in the range of 5.0-8.5. In an alkaline solution, the surface oxide film dissolves, causing corrosion to the metal to extend the service lifetime of the aluminum alloy and save economic cost. Adding a suitable concentration of a corrosion inhibitor can effectively inhibit the erosion of corrosive particles on the metal, thereby slowing down the corrosion of the metal. To align with the development of an ecological civilization, the search for green corrosion inhibitors has become a popular research topic. Betaine organic matter contains N, S, and O atoms as well as aromatic rings, which can be adsorbed on the metal surface to prevent corrosion. In this study, the corrosion inhibition properties of 1-(3-thiopropyl)-2-vinylpyridine betaine (SVPB) alone and mixed with Na2SiO3 both in 0.01 mol·L-1 NaOH solution were investigated on AA2024-T3 aluminum alloys. AA2024 aluminum alloy specimens were laser-cut into two sizes: 20 mm × 30 mm × 3 mm and 10 mm × 10 mm × 3 mm. The surfaces of the specimens were polished with graded sandpaper and cleaned with ethanol and acetone prior to testing. The specimens were immersed in 0.01 mol·L-1 NaOH solution at 30 ℃ for 5.5 h without or with different concentrations of corrosion inhibitor solutions. The weight loss and electrochemical methods, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), quantum chemical calculations, and molecular dynamics simulations were used to investigate the corrosion inhibition effect and mechanism of SVPB alone and in combination with Na2SiO3 on the surface of aluminum alloys. The weight loss method showed that the corrosion inhibition of aluminum alloys using SVPB and Na2SiO3 as corrosion inhibitors alone is not effective. However, the corrosion inhibition efficiency was significantly improved by compounding SVPB with Na2SiO3. The highest corrosion inhibition efficiency was achieved when the concentration of SVPB was 5×10-3 mol·L-1 and that of Na2SiO3 was 7×10-3 mol·L-1, which amounted to 92.37%. The electrochemical impedance spectra showed that with an increase in the corrosion inhibitor concentration, the impedance arcs and absolute value of the impedance modes gradually increased. Moreover, the wider phase angle indicated that the corrosion inhibitor had a good protective effect on the metal. The polarization curves showed that the compound corrosion inhibitor is a hybrid corrosion inhibitor that controls the anodic process, and AFM and XPS showed that the compound corrosion inhibitor can effectively adsorb on the surface of aluminum alloys to form a layer of corrosion inhibition molecules. This layer prevents the metal from corrosion and maintains the smoothness of the metal surface. Computational adsorption modeling showed that the complex corrosion inhibitor complies with the Langmuir adsorption isotherm model. Quantum chemical calculations and molecular dynamics simulations also demonstrated that both SVPB and Na2SiO3 can provide good protection for the surface of aluminum alloys and that the adsorption energy of the complex corrosion inhibitor is more negative than that of SVPB alone. They also showed that the adsorption capacity of the compound corrosion inhibitor on the surface of aluminum alloy is stronger. In this study, a non-toxic, non-polluting green material SVPB was used as a corrosion inhibitor. The corrosion inhibition efficiency was successfully improved by compounding with Na2SiO3.The compounded corrosion inhibitor of SVPB and Na2SiO3 forms a layer of protective film on the surface of aluminum alloys. This layer isolates the surface of aluminum alloys from a corrosive medium. This significantly reduces the corrosive effect of an alkaline medium on the aluminum alloy. These results not only enrich the theoretical basis of the related field but also provide a reliable approach to find environmentally friendly, low-cost, and efficient corrosion inhibitors.
  • First-principles of Oxygen Molecular Adsorption on CrN(111) Surface
    GUI Binhua, ZHOU Hui, WANG Keliang, ZHAO Meng, HE Yanchun, MA Zhanji, YANG Lamaocao
    China Surface Engineering. 2025, 38(4): 294-303. https://doi.org/10.11933/j.issn.1007-9289.20241009004
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    The numerical simulation method has been widely employed for efficient guidance of the preparation and further optimization of the service properties of protective ceramic coatings. These studies mostly focus on the research of structural stability mechanisms improvement of anti-corrosion capabilities, and anti-oxidation behavior promotion. The adsorption states of various corrosive molecules on the surface of protective ceramic coating surfaces are well known to be crucial factors that can determine anti-corrosion and anti-oxidation properties. Therefore, the different adsorption sites of oxygen molecules on the CrN(111) surface were studied systematically utilizing the first-principle of the density functional theory to investigate the underlying adsorption mechanism of oxygen molecules on the nitrogen-based protecting coating surfaces. By constructing stable oxygen molecular configurations at high symmetry adsorption sites on the CrN(111) surface, the adsorption energy, stable adsorption configuration structure, and electron states of the O2 / Cr(111) adsorption system were calculated theoretically to expound the interaction mechanism of atoms in adsorption. The calculations revealed that O2 molecules adsorbed at hollow-Cr sites on the CrN(111) surface exhibit the most intense interaction with the lowest adsorption energy of -5.17 eV. Optimizing the geometric structure of the O2 / CrN(111) adsorption system significantly influenced oxygen molecular surface adsorption, whereby the surface atoms of the CrN(111) plane underwent an obvious structural relaxation phenomenon. The oxygen molecules at the different adsorption sites did not exhibit angular deflection. However, the distance between the top and sub-layer decreased from 1.20 Å to ~1.10 Å, and the bond length of the all-adsorbing oxygen molecules enlarged with a peak value of 1.36 Å at bri-Cr-Cr and hollow-Cr sites. Notably, the adsorbing oxygen molecules of bri-Cr-Cr site transferred to the hollow-Cr site, which also exhibited the lowest distance between the top layer and oxygen molecules, indicating that the hollow-Cr site is the most stable adsorption site of the O2 / Cr(111) system. This aligns well with the adsorption energy results calculated above. As for the different adsorption sites of the O2 / Cr(111) adsorption system, the charge transfer phenomenon between the adsorbed O atom and surface Cr and N atoms was detected to a large extent based on analysis of the electron density distribution and charge population, which indicated the ionic bonding interaction between the O atom and surface Cr / N atoms. The overlap and resonance of the orbit density peaks of the Cr 3s, 3d, and N 2p orbits with the O 2p orbit demonstrated obvious orbital hybridization occurrence. Accordingly, it can be reasonably deduced that the ionic and covalent bonds between the adsorbing oxygen molecule and CrN(111) surface atoms are the fundamental contributors to the formation of the stable adsorption system. Additionally, at the hollow-Cr adsorption site, the density of the energy states of the O2 molecule ranged from -8.0 eV to -6.0 eV, exhibiting an obvious shrinking trend as the density of the states increased significantly. Meanwhile, the locality of 2p orbital of the O2 molecule gradually enhanced, which also indicated that the ionic bond between the O2 molecule and the surface Cr atoms was strengthened, further confirming that the hollow-Cr adsorption site acted as the most stable adsorption site of the O2 / CrN(111) adsorption system. In summary, both ionic and covalent interactions typically co-exist between the adsorbed oxygen molecule and the surface Cr and N atoms, contributing directly to the formation of a stable O2 / Cr(111) adsorption system with the hollow-Cr absorption site being the most favorable.
  • Preparation and Photocatalytic Performance Study of NiO / g-C3N4 Heterojunction Composites
    LI Jing, WEI Wujun, CAI Wenhao, TU Chuanjun, LUO Hong, LIU Yanli
    China Surface Engineering. 2025, 38(4): 304-312. https://doi.org/10.11933/j.issn.1007-9289.20250311001
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    Photocatalysis, characterized by its environmentally friendly nature and high energy efficiency, is a promising technology for treating recalcitrant organic pollutants. Graphitic carbon nitride (g-C3N4), a typical metal-free photocatalyst, has been extensively investigated because of its visible-light response characteristics. However, its practical application remains constrained by inherent deficiencies, primarily the low separation efficiency of photogenerated electrons and holes, leading to their facile recombination. To address these limitations, nickel oxide / graphitic carbon nitride (NiO / g-C3N4) heterojunction composites were fabricated. Pure phase NiO was first obtained via thermal polymerization. Subsequently, the g-C3N4 precursor was mixed with the prepared NiO, and a NiO / g-C3N4 heterojunction composite material was prepared using a hydrothermal method. The morphological features and elemental composition of the synthesized materials were analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS). The results revealed that the spherical NiO particles are intimately integrated with the layered g-C3N4 nanosheets in the prepared samples; furthermore, the presence of C, N, Ni, and O is confirmed. The phase composition and structural integrity were verified by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). The XRD patterns exhibited diffraction peaks corresponding solely to the g-C3N4 and NiO phases, with no evidence of other crystalline phases, indicating the high purity of the prepared samples. The FT-IR spectra further corroborated the presence of characteristic functional groups associated with both g-C3N4 and NiO. X-ray photoelectron spectroscopy (XPS) analysis confirmed successful formation of the composite material. Importantly, the XPS data suggest chemical bonding between the two components. This type of interaction is considered beneficial for the formation of an effective heterojunction, which consequently enhances the photocatalytic performance of the material. The optical properties and band structure of the materials were investigated. Ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) was employed to determine the optical band gaps of g-C3N4 and NiO, which are found to be 2.8 and 3.7 eV, respectively. Mott-Schottky measurements were performed to determine the conduction band (CB) potentials. The CB potential of g-C3N4 was determined to be -1.35 V (vs. SCE, saturated calomel electrode), while the CB potential of NiO was measured as -0.91 V (vs. SCE). The valence band (VB) potentials were calculated by combining the CB potentials with their respective band gaps. The VB potentials for g-C3N4 and NiO were calculated as +1.45 and +2.79 V, respectively (both vs. SCE). These band edge positions provide fundamental insights into the charge transfer mechanism at the heterojunction interface. The photocatalytic activity of the synthesized materials was evaluated for the degradation of tetracycline (TC) solution under simulated natural light irradiation. Among the composites with varying NiO ratios, the optimally performing sample, designated as NiO / CN-2, demonstrated superior photocatalytic degradation efficiency. A removal rate of 79.4% for tetracycline was achieved within 60 min. The degradation rate observed for NiO / CN-2 was also optimal being approximately three times higher than that of pure g-C3N4 and six times higher than that of pure NiO under identical conditions. To elucidate the degradation mechanism, active species trapping experiments were conducted using ammonium oxalate (AO), p-benzoquinone (BQ), and isopropyl alcohol (IPA) as scavengers for holes (h+), superoxide radicals (• O2-), and hydroxyl radicals (• OH), respectively. The experimental results confirmed that •OH and h+ are the primary active species responsible for the degradation of tetracycline in this photocatalytic system. The innovations presented in this work are highlighted as follows: (1) the NiO / g-C3N4 heterojunction photocatalyst was successfully designed and synthesized via a combination of hydrothermal and thermal polymerization methods for the effective degradation of TC in water, (2) the optimized NiO / CN-2 composite exhibited outstanding photocatalytic degradation efficiency towards a TC solution, with its degradation rate showing a substantial enhancement compared to those of both pure g-C3N4 and pure NiO, (3) the mechanism underlying the enhanced photocatalytic performance of the NiO / g-C3N4 heterojunction was investigated using comprehensive characterization techniques and performance evaluations. The crucial role of the heterojunction interface in promoting the effective separation of the photogenerated charge carriers was experimentally confirmed.
  • Wear and Corrosion Resistance Behavior of Multi-metal Layer Coating with Shell-like Structured Texture
    XU Jing, CAI Linxuan, YANG Junyan, LIAO Yihong, LIAN Jiadi
    China Surface Engineering. 2025, 38(4): 313-323. https://doi.org/10.11933/j.issn.1007-9289.20231124002
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    The abrasion of marine equipment has become an important problem in the exploration of marine resources. In order to improve the wear resistance of coatings, a multi-metal layer coating with a bionic nacre texture is proposed, providing an unified design idea of wear and corrosion resistance. Using 316L stainless steel as the substrate, huwen (hw), leitiao (lt) and huanwenleitiao (hwlt) bionic nacre texture is prepared by laser processing, and TiCrCu, TiCr, TiCu, and CrCu multi-metal layer coatings are prepared by physical vapor deposition. Through scanning electron microscopy, energy dispersive spectrometer, friction and wear tester, and electrochemical workstation observation, the wear and corrosion resistance mechanism of the coating and textured surface has studied, and the synergistic mechanism of the texture and coating has analyzed. A new strategy is proposed to improve the defects of the texture and coating. Friction tests showed that in three different environments, the friction factor of the textured coating samples was significantly higher than that of the smooth surface coating samples. The maximum reduction in friction factor is 73%. This is because the texture can convert some sliding friction into rolling friction and form a lubricating film by the stored solution. Corrosion tests showed that the low-frequency impedance and capacitance arc radius of the ribbed textured coatings are greater than those of the ribbed textured samples, and the self-corrosion current density is lower. The corrosion resistance of ribbed textured coating samples has improved 40%-81%. The order of corrosion resistance of the samples is TiCrCu > TiCr > TiCu > CrCu > hwlt, attributed to the dense and uniform multi-metal coating repairing the defects of the texture, filling in micro-nano gaps, preventing the movement of charges, and inhibiting further metal corrosion. Textured multi-metal layer composite coatings can compensate their own defects, and the synergistic effect of textured coatings can effectively improve the abrasion resistance of material surfaces. It provides a new idea for the subsequent research of marine equipment friction corrosion protection.
  • Mechanism of Continuous Laser Cleaning of Composite Paint Layers on Aluminium Alloy Surfaces
    DU Rong, ZHANG Zhiqiang, ZHANG Tiangang, KANG Jiajie, HOU Yunmeng, LIU Hongli
    China Surface Engineering. 2025, 38(4): 324-334. https://doi.org/10.11933/j.issn.1007-9289.20241008001
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    The mechanism of continuous laser cleaning applied to composite paint layers on 2A12 aluminum alloy surfaces was investigated using a combination of experimental methods and numerical simulations. The impact of different laser scanning speeds on paint removal effects was examined, along with the underlying interactions between the laser and material. Conventional paint removal techniques, such as chemical and mechanical methods, are limited in effectiveness and are often detrimental to the substrate. This emphasizes the advantages of laser cleaning as a non-contact, environmentally friendly alternative. High-strength aluminum alloys, which are widely used in aerospace applications owing to their excellent strength-to-weight ratio, often undergo surface coating degradation over time. Laser cleaning, with its high precision and minimal environmental impact, offers an efficient solution for maintaining the performance and longevity of these alloys. COMSOL Multiphysics software was used to simulate the laser paint removal process, focusing on the temperature and stress distributions within the composite paint layers. A CO2 continuous laser was used to conduct experiments at three scanning speeds (3 000, 2 100, and 1 200 mm / s). The effects of laser cleaning on the surface composition and microstructure were analyzed using various characterization techniques, including optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. Detailed insights into the physical and chemical changes induced by the laser interaction with the composite paint layers are provided through these analyses. The scanning speed was found to play a critical role in determining the paint removal efficiency and paint removal effect. At the highest scanning speed (3 000 mm / s), only a small amount of topcoat was removed, leaving the primer largely intact. At a medium speed (2 100 mm / s), most of the primer was successfully removed, exposing significant portions of the oxide layer. At the lowest speed (1 200 mm / s), cracks appeared in the oxide film, and visible pits formed at the junctions of these cracks. Therefore, slower scanning speeds are suggested to allow greater energy absorption by the material, leading to more pronounced ablation effects. Conversely, higher scanning speeds reduce the effectiveness of the laser in cleaning the paint layer, as rapid movement across the surface limits heat absorption. At this stage, the thermal vibration effect becomes more significant and contributes to paint removal. Two primary mechanisms of paint removal were identified: ablation and thermal stress-induced vibration. Ablation was more prominent at lower scanning speeds, where longer laser exposure times resulted in more efficient energy transfer and stronger thermal effects. At higher scanning speeds, rapid laser movement across the surface generated substantial temperature gradients, leading to increased thermal stress vibrations that aid paint removal. These mechanisms were validated using both experimental data and simulation results. A key contribution of this study is the comprehensive analysis of the continuous laser cleaning process, integrating experimental observations with numerical simulations to provide a detailed understanding of the thermal and mechanical phenomena involved. This research underscores the importance of laser scanning speed to balance efficient paint removal with substrate protection. Specifically, excessive laser exposure at low speeds can damage the oxide layer, whereas insufficient exposure at high speeds may leave significant paint residue. In conclusion, a comprehensive understanding of the underlying mechanisms involved in continuous laser paint removal from aluminum alloy surfaces was provided. By revealing the key roles of ablation and thermal stress-induced vibrations, this research enhances our knowledge on how different laser scanning speeds affect the efficiency of paint removal and condition of the substrate. These findings offer crucial insights into the interactions between laser and composite paint layers, which are essential for the development of more effective laser cleaning processes. These results have substantial implications for industrial applications, particularly in sectors such as aerospace, in which precise surface treatment is critical for maintaining material integrity and performance over time.
  • Path Planning and Realization of Complex Surface Based on a Laser-cladding Robot
    SONG Yujie, WU Yifa, ZU Haiying, CHEN Wenqi
    China Surface Engineering. 2025, 38(4): 335-346. https://doi.org/10.11933/j.issn.1007-9289.20240604002
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    Currently, laser-cladding technology is used to repair local damaged surfaces of simple plane parts; however, remain several problems in the laser cladding repair of complex curved parts. The flexibility and applicability of laser cladding remanufacturing have been greatly improved by employing industrial robot technology and laser cladding technology in conjunction. This led to a new idea for the laser-cladding processing of complex surfaces. The curvature radius of a complex surface varies widely, and the normal vector of every point on the surface is irregular, increasing the difficulty of laser cladding path planning. Trajectory planning is employed to design a reasonable cladding path to improve cladding quality, which is also the goal of domestic and foreign scholars for conducting in-depth research on the cladding path. The laser cladding path generation of complex surfaces was studied in combination with reverse engineering and robot technology to realize the application of laser cladding remanufacturing technology on complex surfaces. The solid model of complex surface parts was obtained based on reverse engineering technology. A three-dimensional laser scanner was used to collect the point cloud data of complex surface parts, and the point cloud data was preprocessed to obtain the rotor triangular surface model. The complex surface was fitted according to the NURBS surface fitting theory and the reverse solid model was obtained. The laser cladding path planning for complex surfaces was also studied. The initial cladding path was obtained using the intersection method between the isometric cutting plane and triangular surface. The initial path was discretized based on the equal arch height error method, and the normal vector of the interpolation points was estimated using a normal vector. According to the scanning sequence, the local Cartesian coordinate system of the interpolation points was established for obtaining the pose of each interpolation point, and the path smoothing was performed on the laser coating path. Research on kinematics analysis and trajectory planning of laser cladding robot was conducted. The mathematical model of the six-axis industrial robot was established by using the improved D-H parameter method, the forward and inverse kinematics equations of the robot were deduced and verified, and the kinematic relationships and decoupling in the machining process were analyzed. A simulation platform for laser cladding trajectory planning was developed. An off-line programming software, PQart, was used to create the machining scene, conduct path simulation, verify the feasibility of the trajectory, and post the machining code. A multibody model of the laser coating platform was built in MATLAB Simulink, and the angular change value of each joint in the machining path was considered the joint drive. The motion characteristic curves of the angular displacement, angular velocity, and angular acceleration of each joint were analyzed over time. Combined with the previous studies, suitable materials and process parameters were selected to perform laser-cladding experiments of complex curved surface robots. The rationality and effectiveness of path planning were verified by analyzing the operating posture of the robot and the surface topography of the curved cladding layer in the actual machining process. The results indicated that the maximum arch height error between the laser cladding processing path and surface contour under the proposed method was within the set target value range, the surface of the cladding surface was smooth, the ripple was small, the overlap was good in the part with a large curvature change, and the overall molding quality was good, thereby verifying the rationality and effectiveness of the path planning. Thus, this study provides a reference for applying laser cladding remanufacturing on complex surfaces.
  • Slip and Heat Characteristics of a Cylindrical Roller Bearing with Textured Pockets
    LIU Yanbin, LI Xuying, NING Zhong
    China Surface Engineering. 2025, 38(4): 347-362. https://doi.org/10.11933/j.issn.1007-9289.20240806003
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    Cage slip and frictional heat arise easily in cylindrical roller bearings under high-speed operating conditions, leading to bearing wear and thermal failure. Thus, this problem needs to be urgently solved to realize high-speed cylindrical roller bearings. In a cylindrical roller bearing with circular pockets, the circular pocket-roller is a high-slip-speed dynamic-contact conformal contact pair. Accordingly, the surface texture of the circular pocket affects the pocket lubrication, cage slip, and friction heat of the bearing; however, its influence mechanism remains unknown. Therefore, an E-NU308ETVP7 cylindrical roller bearing with circular pockets was considered as a research example in this study, and a conformal dynamic contact lubrication model of the groove-texture circular pocket-roller was established based on the dynamic Reynolds equation and the Winkler elastic foundation model. Further, the dynamics model of the bearing was designed using the Newton-Euler dynamics theory, and the coupling solution of the pocket lubrication and bearing dynamics models were obtained using the finite difference, multi-grid, and Runge-Kutta integration methods. The reliability of the coupling model and the solution method was validated by comparing the simulation data with the experimental data from the literature. The transient pressure and thickness distributions of the pocket oil film, cage slip rate, and bearing friction power consumption under different operating conditions, including different texture area ratios, different groove numbers, and different groove depths of the groove texture of the pocket were calculated using this model. Further, the effects of the texture area ratio, groove number, and groove depth of the pocket on the pocket lubrication, cage slip, and bearing friction heat were investigated. Consequently, the pressure and thickness distributions of the pocket oil film were found to depend closely on the azimuth angle of the roller. The oil film pressure of the roller and the rear side of the pocket was found to be considerably greater than that of the roller and the front side of the pocket in the non-load area of the bearing. In the load area, the oil film pressure of the roller and the front side of the pocket was considerably greater than that of the roller and the rear side of the pocket. The groove-texture pocket ensures the fluid dynamic pressure affects both sides; the non-texture pocket cannot ensures the effect of the fluid dynamic pressure on both sides. When the texture area ratio is 0.67 and the groove number is 2, the simulation results obtained by changing the groove depth from 0 to 0.21mm showed that the slip rate of the groove-texture cage is lower than that of the non-texture (the groove depth is equal to 0) cage. Further, the friction power consumption of the bearing is also lower, and within the range of the groove depth less than 0.17 mm, the cage slip rate and friction power consumption of the bearing decrease with an increase in groove depth. However, the cage slip rate and friction power consumption of the bearing have a slight rebound when the groove depth is greater than 0.17mm. The simulation results obtained by changing the texture area ratio from 0.17 to 0.97 when the groove depth is 0.05 mm and the groove number is 2 show that the cage slip rate and friction power consumption of the bearing decreases with an increase in the texture area ratio. The simulation results obtained by changing the groove number from 2 to 9 show that the groove number has a slight effect on the cage slip rate and friction power consumption of the bearing when the groove depth is 0.05mm and the texture area ratio is 0.67; however, the influence laws are not obvious. In summary, a coupling model of the pocket lubrication and roller bearing dynamics was built, and the influence laws of the groove texture of the circular pocket on the pocket lubrication, cage slip, and bearing friction heat were explored. This study can provide a reference for the tribology / dynamics coupling analysis and the anti-slip and anti-friction research on cylindrical roller bearings.
  • Regular Textured Surface on the Lubrication Behavior of Aerodynamic Journal Microbearings
    WU Yao, HAN Leng, XI Wenjun, LIU Zhao, XIN Hua, ZHANG Meng
    China Surface Engineering. 2025, 38(4): 363-381. https://doi.org/10.11933/j.issn.1007-9289.20241031008
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    Micro-textures refer to micro-protrusions or dimples of specific sizes and arrangements that are artificially fabricated on the surface of friction pair materials. These textures alter the surface morphology of the friction pair to improve surface contact conditions or lubrication performance. Surface micro-texturing technology enhances the lubrication performance of sliding bearings; however, there is currently a lack of systematic and in-depth analysis of the lubrication mechanisms of textured micro gas-lubricated bearings, particularly regarding the effects of the shape, size, distribution, and applicable working conditions of surface micro-textures. This paper introduces a compressible gas lubrication model based on the rarefied effect model of the Boltzmann equation considering the parity consistency of the ultrathin gas film and individual texture grid. The gas film thickness includes the smooth region gas film gap and depth of the surface micro-texture. The size of the surface micro-texture directly affects the number of grids, and it is essential to ensure that the ultrathin gas film and textured surface adopt the same and uniform grid for superimposed calculations. If the number and positions of the grids are inconsistent, the corresponding grid nodes will not match one-to-one, which makes it impossible to express the derivatives of gas film thickness and pressure at each grid node in the form of finite differences between adjacent nodes based on the central difference principle. This study systematically investigates the variations in the load capacity, friction coefficient, and maximum gas film pressure of micro-bearings with respect to different texture shapes (convex / concave) such as rhombic, hexagonal, cylindrical, spherical, square, and equilateral triangular textures, as well as bearing structural parameters by combining the central difference method and the over-relaxation iterative method for numerical solutions. The results indicate that when the aspect ratio of the micro gas bearing is small, and the effects of surface micro-texture shape and convexity / concavity can be neglected. Compared to smooth surface micro gas bearings, the load capacity and friction coefficient of concave-textured micro-bearings gradually decrease with an increase in the number of axial and circumferential textures, while convex-textured micro-bearings exhibit enhanced load capacity and friction coefficient. Among convex textures, hexagonal textures show the most significant enhancement, followed by square, cylindrical, rhombic, spherical, and equilateral triangular textures. The larger the texture area ratio and eccentricity, the greater is the fluctuation in load capacity and friction coefficient. The load capacities and friction coefficients of convex-textured micro-bearings increase with the texture depth, whereas the concave-textured bearings exhibit the opposite trend. Placing convex micro-textures in the central region of the gas film can maximize the gas film pressure, indicating that the central region of the gas film is inherently a high-pressure zone. The presence of convex textures further compresses the rarefied gas, increasing flow resistance, enhancing the dynamic pressure effect, and raising the pressure gradient, which effectively improves the pressure peak. Placing convex textures in the convergent region of the gas film can have adverse effects. This phenomenon occurs because convex micro-textures at the entrance of the convergent region disturb the airflow, weaken the dynamic pressure effect, and introduce irregular pressure gradients because of local flow channel blockage, affecting the overall maximum pressure of the gas film. Therefore, establishing a lubrication model for ultrathin gas films in gas-lubricated journal microbearings with flexible and controllable surface texture parameters provide a theoretical foundation and technical support for designing optimal surface texture parameters and achieving the best lubrication performance of self-acting gas microbearings. This has significant application value in improving the operational stability of micromechanical devices.
  • Magnetic Abrasive Finishing Process for the Inner Surface of Brass Tube Based on Permanent Magnet Alternating Magnetic Field
    YAN Yuhang, DING Yunlong, YING Jun, SUN Yan, HAN Bing, JU Dongying
    China Surface Engineering. 2025, 38(4): 382-392. https://doi.org/10.11933/j.issn.1007-9289.20240511001
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    ：Improvements were proposed to meet the finishing needs of various precision components and resolve the problem of constant magnetic field and aggregation of magnetic abrasive particles during the processing on inner surface defects of brass pipes. H65 brass tube is a common brass alloy with good corrosion resistance and conductivity. It is widely used in various fields, especially in the fields of pipelines and high-end electronic optical medical equipment, where the inner surface has high quality requirements. A magnetic abrasive finishing method is used to process the H65 brass tube. However, when using traditional magnetic abrasive finishing methods, the magnetic field in the processing area inside the tube is fixed, and it cannot update the magnetic abrasive particles participating in grinding in real time. Thus, the magnetic abrasive particle has only a single trajectory. A new type of permanent magnet alternating magnetic field generating device has been designed for complicating the magnetic field in the processing area inside the tube, diversifying the movement trajectory of magnetic abrasive particles, enhancing the self-sharpening capability of magnetic abrasive particles, and improving grinding efficiency. The developed device is based on a CNC machine tool, and the rotation of permanent magnet pole inside the grinding head is controlled by a stepper motor to achieve an alternating magnetic field. A three jaw chuck was applied to clamp the H65 brass tube and control its rotation speed, and pulse generator was used to control the speed of stepper motor, which allows controlling the alternating frequency of the magnetic field. A magnetic field simulation software was used to conduct a simulation on a permanent magnet alternating magnetic field under different states. The magnetic field type was set as a transient field, followed by modeling and defining material properties. The air and rotation domains was set to define the magnetic field range and the rotation of magnetic pole. The results of the simulation indicate that the magnetic field distribution of the permanent magnet alternating grinding head can be separately displayed as magnetic and non-magnetic to external states. The optimal process parameter ranges for magnetic pole speed, spindle speed, and mesh of abrasive as single variables were obtained through single-factor experiments: magnetic pole rotation speed = 60 r / min, 90 r / min, 120 r / min; mesh of abrasive = 60 #, 80 #, and 100 #; and spindle speed = 800 r / min, 1000 r / min, and 1200 r / min. Under the conditions of grinding time of 15 min, processing gap of 1.5 mm, and feed rate of 5 mm / s, 15 controlled experiments were designed using the response surface method to compare the machining effects on the inner surface of brass tubes under different parameters. A variance analysis was conducted on the experimental results, which revealed that factors affecting the surface roughness were magnetic pole rotation speed (A), mesh of abrasive (B), and spindle speed (C), in order. The optimal process parameters are a magnetic pole rotation speed of 95.921 r / min, abrasive mesh of 88.057 #, and spindle speed of 914.320 r / min. After grinding with the best process parameters, the inner surface of brass tube was measured using a super depth of field 3D electron microscope and a stylus surface roughness measuring instrument. The original tensile texture, pits, and grooves on the inner surface of brass tube were removed after grinding, and the surface roughness was reduced from the original Ra 0.581 μm to Ra 0.070 μm. The experimental results show that the permanent magnet alternating magnetic field can achieve the rolling motion of magnetic abrasive particles inside the tube, making it possible to improve the cutting ability, utilization rate, and grinding effect of magnetic abrasive particles. A magnetic abrasive finishing device based on permanent magnet alternating magnetic field was designed, and the experimental data was optimized using response surface methodology to determine the optimal process parameters.
  • Process and Properties of Plasma Electrolytic Surface Quenching of 4Cr13 Steel
    DAI Fengxian, NIU Chenrui, ZHANG Junjie, LIU Zigang, LI Yang
    China Surface Engineering. 2025, 38(4): 393-401. https://doi.org/10.11933/j.issn.1007-9289.20240816001
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    4Cr13 stainless steel is a commonly used stainless steel, a heat treatment process, such as quenching can improve the hardness and strength of 4Cr13 steel, and it has excellent cutting performance and wear resistance. Plasma is used as a heat source to quench the surface of 4Cr13 steel. Its principle is based on the high-temperature plasma generated by electrolyte discharge to quench the surface. The 4Cr13 steel sample is used as the cathode and anode nozzle for maintaining a certain gap, and the electrolyte jet emitted through the anode nozzle is connected with the workpiece and electrified, thereby forming a current in the electrolyte between the anode nozzle and sample, and finally-inducing a plasma discharge on the surface of the sample to be heated, to realize the heating of the sample surface to be treated. In this test, the voltage between the anode nozzle and surface of 4Cr13 steel sample is changed in a pulsed manner for periodic heating and insulation, controlling the heating rate of the surface of 4Cr13 steel, and avoiding the surface topography of the heating area to exhibit ablation and melting, thereby resulting in fine deformation. The electrolyte not only serves as the plasma source, but also serves as the cooling medium to cool the heating zone. Therefore, the cooling rate of the surface is controlled by controlling the flow rate of electrolysis, to control the generation of martensite. The holding time is the main factor that affects the hardening depth of the hardening area, and the main function of the holding voltage is to maintain balance between the heating rate and cooling rate, and allow sufficient time for austenitizing to increase the range of the heating area. The energy density in the plasma layer is controlled by the electrolyte and the voltage to change the heating and cooling rate of the surface layer to control the martensitic grain growth and affect the hardness and hardening depth of the surface layer. Therefore, it is necessary to carry out experiments on influencing factors such as heating voltage, holding voltage, treatment time, and electrolyte flow rate for obtaining the optimal process parameters of plasma electrolytic heat treatment, and analyzing the influence of various process parameters on the hardness and hardening depth of hard layer, to determine the process parameters of plasma electrolytic heat treatment of 4Cr13 steel. The results indicate that, after the heating voltage of 320V and the holding voltage of 280V, single treatment times of 3 s and 8 s are alternately implemented five times, and the surface appearance of the heating area does not exhibit melting ablation, The hardness of the hardening layer in the quenching area can reach about 800HV0.1, and the hardness of the central hardening layer in the heating area can be increased by 3~4 times compared to that of the substrate. The hardening depth of 500HV0.1 and above reaches 2~3 mm. The heating range of the heating area is determined by the diameter of the anode nozzle, and the components of different sizes can be heated. The innovation point of the plasma electrolytic heat treatment technology is that the heating and cooling rate can be controlled, and the electrolyte can be used as a plasma forming material while the electrolyte can cool the heated surface to achieve rapid self-cooling. Plasma electrolytic heat treatment technology is used for complex shape parts and local hardening is used for other parts that can-not be treated by other conventional methods for local hardening treatment, but also according to the need for hardening in different parts of the same part for achieving alternating soft and hard tissue to increase the wear resistance of parts. This can make the hardened layer to form layer by layer, ensure the multiple refinement and homogenization of austenite grains before quenching, and obtain the alternate soft and hard structures, reduce stress, and improve the impact toughness of the workpiece under high hardness. In this paper, the research status of the electrolytic plasma surface quenching technology is presented, and it is helpful to apply electrolytic plasma surface quenching technology to strengthen the surface quality of 4Cr13 steel and the optimization of the process route.
  • Surface and Coating Properties of GI-coated Hot-formed Steel
    LONG Yuan, LI Xuetao, HAO Yulin, ZHANG Boming, XU Dechao, LIU Huasai, WANG Songtao
    China Surface Engineering. 2025, 38(4): 402-413. https://doi.org/10.11933/j.issn.1007-9289.20240728003
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    Hot-formed steels consist of uncoated and coated hot-formed steels. Among the coated hot-formed steels, aluminum-silicon (Al-Si) coated and zinc-based coated steels are predominant, with Al-Si coated steels being the most widely used at present. Zinc-based coatings are restricted because of zinc volatilization and liquid metal embrittlement, and its surface properties have adverse effects on coating and welding, thereby preventing their widespread application. Currently, most research focuses on the first of the two issues, while fewer scholars have investigated the effect of zinc-based coatings on painting performance. Existing studies provide only a simple evaluation of painting quality. The effect of surface condition after heat treatment on paint quality, combined with the reaction mechanism of pre-treatment for painting and the requirements of electrophoretic properties were investigated using scanning electron microscopes, X-ray photoelectron spectroscopy analyzers, electrochemical workstations, forming testers, and cyclic corrosion testers to analyze the structural composition of the coating, corrosion resistance, morphology of the phosphating film, growth process of the phosphating film, and performance of the electrophoretic paint film. The research results are as follows: Before the heat treatment of the steel plate, the microscopic morphology of the coating is a typical morphology of galvanized sheets; there are obvious skin pass marks on the surface; the average values of roughness Ra and RPc are 0.973 µm and 93.2 cm-1 respectively; the thickness of the coating was about 10 µm; and more than 99.8% of the components of the coating was zinc, with a small amount of aluminum and iron. After heat treatment, obvious alloying occurred in the coating and the surface became rough and uneven. The roughness Ra and RPc were 1.415 µm and 110.3 cm-1, respectively. The thickness of the coating increased to 25-28 µm and was divided into four layers. The outermost layer of the coating to the iron substrate included the oxide layer, Γ phase, α-Fe(Zn) phase, and iron substrate, in sequence. Among them, the oxide layer was a composite compound containing Al2O3, MnO, Fe2O3, and ZnO with a thickness of 2-4 µm. In a 3.5% NaCl solution, the corrosion resistance of the coating with the oxide layer was better than that of the coating without the oxide layer. However, the oxide layer inhibited the formation of the phosphating film, leading to a phosphating film coverage rate below 100%. Extending the degreasing time to dissolve amphoteric oxides in the oxide layer did not effectively improve the phosphating film coverage. Removing the oxide layer by sandblasting was necessary to form a uniform, dense, and 100% coverage phosphating film on the coating surface, which significantly improved its corrosion resistance and was superior to that obtained without removing the oxide layer. The test of the electrophoretic paint film showed that removing the oxide layer had a minor impact on the cross-cut adhesion (rated as 0); however, it significantly affected the cupping performance of the paint film, increasing the cupping fracture height from 6 mm to 7 mm after the oxide layer was removed. The under-film expansion corrosion performance also improved, reducing the one-sided expansion width from 1.78 mm to 0.98 mm. The oxide layer generated during heat treatment obviously caused the decline of the phosphating performance of the coating and the performance of the electrophoretic paint film. Analyzing the effect of the surface condition of pure zinc-coated hot-formed steel after heat treatment on paint performance helped clarify the mechanism of how the oxide layer affects the phosphating film and electrophoretic corrosion resistance. Thus, removing the oxide layer is an important method to improve the painting quality of this material.
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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