In the current era of industrial manufacturing and materials science, continuously enhancing material properties to meet the growing application challenges is an ongoing task. Metal materials play a key role in many industries because of their excellent mechanical properties and wide range of applications. Nevertheless, these metals are often subjected to wear, corrosion, and fatigue damage during practical use, which severely reduces their service life and reliability. Therefore, studying effective surface modification technologies that can improve the surface integrity and properties of metals has become a core issue in materials science research. Ultrasonic surface rolling processing (USRP) is an advanced material surface modification technology that combines ultrasonic energy and high-frequency mechanical vibrations to nano-strengthen the metal surface. This technology can cause plastic deformation on the surface of the material and significantly improve its surface integrity and mechanical properties. USRP can generate residual compressive stress on the surface of a material, effectively preventing the formation and expansion of cracks and reducing the permeability of the corrosive medium. In addition, this technology can form a nanostructured layer with a gradient grain size and orientation, thereby significantly enhancing the surface hardness and wear resistance of the material. This review summarizes the research progress in USRP in the fields of steel, aluminum alloy, titanium alloy, magnesium alloy, nickel alloy, and high-entropy alloy. It is demonstrated that these materials have achieved remarkable results in surface nano-strengthening and microstructural and performance improvement following USRP treatment. USRP technology can not only refine the grain size, reduce the surface roughness, and improve the surface hardness, but also convert the residual tensile stress into residual compressive stress to obtain a deeper nano-gradient hardened layer and residual compressive stress-affected area. This compensates for the low production efficiency of traditional mechanical processing methods as well as the mismatch between the working environment and performance requirements of high-performance materials. Finally, future application prospects and development directions of USRP are discussed. It is expected that focus will be placed on the refinement of theoretical models and the diversification of working methods. This research will further explore the theory of contact mechanics and surface integrity to develop a prediction model that can optimize the process parameters. In addition, USRP technology will be adapted to deal with complex parts and improve the efficiency and performance through multi-field coupling and process integration. The expansion of the application range will include composite materials and high-tech fields, including deep-sea exploration and aerospace satellites.

Continuous-fiber-reinforced resin-based composite materials represent a novel class of high-performance composites that have gained traction in recent years. The use of additive manufacturing technology for fabricating these composite materials offers significant advantages, including enhanced manufacturing flexibility and high forming efficiency, thereby making it a key research focus. Herein, the characteristics of both resin matrix and fiber materials are summarized, followed by an examination of the extrusion and impregnation processes involved in the additive manufacturing of continuous fiber-reinforced resin-based composites. Furthermore, the impact of process parameters such as temperature, printing speed, and printing spacing on the material are discussed. Additionally, the microstructure at the fiber-matrix interface and between layers are discussed, in addition to the mechanical properties of the material, including tensile and bending strengths. Finally, the challenges associated with increasing demand and performance limitations in the additive manufacturing of these composites are highlighted, proposing recommendations for their development, such as enhancing material recyclability and optimizing the additive manufacturing process. Both thermoplastic and thermosetting resins typically serve as matrix materials. Thermoplastic materials, exhibiting relatively low melting temperatures, facilitate processing in additive manufacturing. However, the high viscosity of these materials contributes to the low impregnation between fibers and resin, resulting in relatively lower mechanical properties than those of continuous fiber-reinforced composite materials produced via conventional methods. Conversely, thermosetting materials exhibit low viscosity, thereby enhancing fiber impregnation. However, they present challenges in the formation of composite materials, thereby increasing production costs. Additionally, additive manufacturing of thermosetting composite materials generates waste, contributing to material loss. Therefore, investigating the recyclability of these materials remains a crucial area for future research. The additive manufacturing process for continuous fiber-reinforced composite materials is influenced by factors such as fiber impregnation, material extrusion, fiber volume fraction, fiber orientation, and processing temperature, all of which influence material formation. However, significant challenges persist in additive manufacturing, and further improvements in the manufacturing process are essential. Research indicates that compared with composite materials produced via conventional processes, those fabricated via additive manufacturing exhibit lower mechanical properties. The primary factors influencing the mechanical properties of the final material include the bonding between the fiber-matrix interfaces as well as between layers. Inadequate bonding between the materials results in pore formation, causing stress concentration within the material and reducing its mechanical properties, thereby accelerating material failure. To further enhance the performance of fiber-reinforced composite materials and address existing limitations, future research must prioritize the following aspects. First, different matrix materials exhibit distinct effects on the performance of composite materials. Selecting an appropriate matrix material is crucial, necessitating further research into novel resin matrix materials. Additionally, as the use of composite materials increases, their recyclability has become as a critical constraint for industrial applications. Therefore, future research on material recyclability must be prioritized. Second, in the context of additive manufacturing of composite materials, in addition to the inherent properties of the materials, multiple avenues for process improvement exist. The impregnation process can be optimized via auxiliary techniques, such as plasma and oxidation treatments. Furthermore, controlling process parameters such as printing speed, temperature, and environmental conditions is essential for ensuring consistent material properties. Further investigation into the influence of these parameters on the material properties is necessary. Third, defects such as low interface performance and porosity in composite materials are typically attributed to insufficient compaction during the manufacturing process. Improving the compaction process or performing post-processing on the material can significantly enhance the performance of additive manufacturing.

Laser cladding (LC) is an advanced material surface-modification technology. Fe313 is a widely used LC material. The addition of WC (hard phase) to the Fe313 powder can enhance and improve the wear resistance of the cladding. However, WC increases the difference in the thermophysical properties inside the cladding and between the cladding and substrate, resulting in cladding defects. Therefore, it is important to monitor the cladding defects and achieve feedback regulation. Acoustic emission (AE) refers to the phenomenon of transient elastic waves emitted due to the rapid release of the local energy of the material. During the LC process, owing to differences in the defect type, size, shape, position, and other factors, each type of defect can generate a unique AE signal. The relationship between the AE signal characteristics and defects was established by extracting the characteristics of the AE signal. Combined with a deep-learning algorithm, an identification method for the LC process state and defects was designed, which can lay a foundation for improving the quality of LC. To conduct the full-cycle monitoring of the LC process, the entire process was divided into five states: powder feeding, melting, cooling, cracking, and porosity. In this study, 45 steel was used as the cladding substrate and 30wt.% WC_p/Fe as the cladding powder. A single-layer, single-pass LC experiment was designed to collect AE signals during cladding. The samples were then cut, ground, and polished. The internal defects in the samples were observed using a super-depth microscope. A quantitative correlation between the number of defects and AE signal was determined by comparing the results of super-depth microscopic images and AE signals. A single-layer multipass LC experiment was designed, and the AE signals of the five states during the cladding process were collected. The AE signals of the five states were analyzed in the time, frequency, and energy domains. Appropriate LC process parameters for repeated tests were selected to obtain and create a dataset. To avoid significant differences in the feature values and discrete distributions between the data samples, the dataset was preprocessed using maximum normalization. An LC state recognition network model based on a Residual Network (ResNet) was designed to determine the LC state, and the AE signal samples of each cladding state containing 1024 signal features were input into the model. Then, the processing was carried out sequentially through convolutional layers, pooling layers, residual modules, and linear layers, and the recognized LC state was the output. Finally, using an LC defect number and duration recognition algorithm, the number of defects generated and the duration of each type of defect were identified. The AE signals of the five LC states were collected in a single-layer multipass LC experiment. From the time-domain perspective, the absolute amplitudes of the five LC states were sorted from largest to smallest as follows: crack, porosity, cooling, melting, and powder feeding states. From an energy perspective, the amplitudes of the five cladding states were sorted from largest to smallest as follows: crack, porosity, cooling, powder feeding, and melting states. In the frequency domain, the frequency bands of the five LC state signal samples were concentrated at approximately 150 kHz, and the identification method of AE signals for LC defects and states based on deep learning could effectively distinguish between the current LC state and the occurrence of defects. The identification accuracy was 97.74% for the unfamiliar datasets. The AE technology, as a nondestructive testing method, can monitor and identify defect signals in the LC process in real time. Deep learning methods, characterized by strong adaptability and high recognition accuracy, can handle complex nonlinear signals. By combining these two methods, new ideas and approaches are provided for the intelligent development of LC technology, and technical support is provided for the feedback control of LC.

Inspired by Nepenthes pitcher plants, slippery liquid-infused porous surfaces (SLIPS) were first created in 2011 to offer a novel approach to surface engineering. Unlike conventional superhydrophobic surfaces (SHS), which rely on air lubrication, SLIPS utilize liquid lubrication with superior durability and pressure stability. With such advances, SLIPS possess outstanding liquid and ice repellency, self-healing, and enhanced optical transparency, which can be implemented in a wide range of energy applications, such as industrial anti-icing, anti-fouling, anti-frosting, and droplet-based power generation. Because most industrial application scenarios for SLIPS frequently encounter impacts of droplets, a mechanistic understanding of the dynamic interactions between SLIPS and impacting droplets is essential for the effective use of SLIPS under specific application conditions. This review systematically examines droplet impacting dynamics on SLIPS. In section 1, we introduce the thermodynamic conditions required to form effective SLIPS and their fabrication methods. There are two major criteria to achieve stable SLIPS: 1. lubricant spreading on the substrate, characterized by the spreading parameter (S) and 2. stabilization by van der Waals forces, characterized by the disjoining pressure or corresponding Hamaker constant (A). The fabrication of SLIPS involves structural treatments on substrates that are followed by chemical functionalization and the final lubrication selection. Based on the substrate structure, SLIPS can be categorized into 1D-SLIPS, 2D-SLIPS, and 3D-SLIPS based on the structural hierarchies varying from one-dimensional mono-molecule layers to two-dimensional micro- / nano-surface structures to three-dimensional crosslinked polymer matrices, respectively. In section 2, we summarize the dynamic behaviors of droplet impacts on SLIPS, including deposition, complete rebound, partial rebound, jet, and splash behaviors under conditions with different Weber numbers or other related dimensionless numbers. As the Weber number increases, the dynamic behaviors of droplets impacting SLIPS transitions from deposition to rebound and eventually to splash. The higher Weber number of a droplet indicates higher inertia before impacting the surface, which introduces stronger inertial forces to overcome the capillarity of the droplet. Eventually, these properties force the droplet to splash into smaller drops. Compared with many solid surfaces, SLIPS demonstrate a higher probability of droplet rebound, resulting in their advantages in the applications of anti-icing and anti-frosting. In section 3, we analyze the spreading dynamics, retraction dynamics, and contact time of SLIPS. In general, the droplet impacting on SLIPS experiences spreading and retraction processes. During the spreading process, the diameter of the droplet in contact with the surface gradually increases until the droplet spreading diameter reaches its maximum, driven by inertial forces. Subsequently, the droplet enters the retraction process under capillary and viscous resistant forces. The maximum spreading diameter can be scaled as β_max ~ We^1/4 in most conditions. Moreover, the retraction dynamics dominated by viscous forces are affected significantly by the lubricant viscosity. With the increase of the contact angle and the decrease of the lubricant viscosity, the retraction velocity tends to be higher. Further, the contact time is mainly affected by the diameter of the droplet and the lubricant viscosity but is independent of the droplet impact velocity. Compared with superhydrophobic surfaces, the contact time on SLIPS is generally longer owing to viscous retention. In section 4, the different application potentials of SLIPS are systematically summarized. The stability and self-healing of SLIPS are advantageous for the applications, including anti-icing, anti-fouling, fog harvesting, and electricity generators. These applications with SLIPS may revolutionize the modern biomedical devices, solar panels, wind turbines, and small-scale energy generators. Finally, the dynamic characteristics of droplets impacting the SLIPS and the research direction are summarized and prospected. This review provides a comprehensive understanding of the key physical principles underlying the phenomena of droplet impacts on SLIPS as well as further application conditions of SLIPS in energy industries, including industrial anti-icing, defrosting, surface-enhanced heat transfer, and electricity generation from droplets.

Single-crystal diamond (SCD), owing to its exceptional physical properties—including an ultrawide bandgap of 5.5 eV, an extremely high breakdown electric field of 9.9 MV / cm, and an outstanding thermal conductivity of 22 W / (cm·K)—is widely recognized as a revolutionary material capable of overcoming the performance limitations of silicon-based integrated circuits (ICs). However, the extraordinary hardness (Mohs hardness of 10) and extreme chemical inertness of diamonds present significant challenges for achieving atomic-level surface polishing, which is crucial for their application in high-end chip manufacturing. This study focuses on the development of atomic-level polishing techniques for SCD, systematically reviews the evolution of polishing technologies from micro / nanoscale to atomic precision, and identifies key breakthroughs to overcome existing machining limitations. Additionally, this study examines the characteristics and applicability of various polishing methods, thus providing valuable insights for practical implementation. First a mechanical polishing techniques, including conventional and ultrasonic-assisted methods, are investigated comprehensively. Whereas these approaches offer straightforward processes, the inherent “hard-on-hard” friction inevitably introduces surface defects, thus rendering it difficult to achieve subnanometer surface smoothness. Subsequently, high-energy beam polishing technologies, such as lasers, ion beams, and plasma polishing, are examined. Although these methods replace abrasive particles with high-energy particles, issues such as inferior selectivity, deep thermally affected zones, and particle implantation limit their ability to achieve low subsurface damage and subnanometer planarization. The third category, i.e., multifield coupled polishing, which includes chemical-mechanical polishing and plasma-assisted polishing, leverages synergistic effects for surface planarization. However, these methods are characterized by complex processes and low polishing rates. Based on a detailed comparative analysis, this study highlights the significant challenges in satisfying the stringent requirements of IC manufacturing: subnanometer precision, minimal damage, and high processing rates. The findings suggest that, although existing polishing techniques are adopted in specific applications, they remain inadequate for completely satisfying the abovementioned demanding criteria. Achieving atomic-level surface polishing requires not only gradual process improvements but also systematic innovations in theoretical understanding and process development. This study emphasizes the necessity of cross-scale control from macroscopic process parameters to microscopic atomic behavior to precisely regulate material removal mechanisms, including the synergy between mechanical shear and chemical etching, as well as the energy threshold for atomic bond breaking. At the fundamental research level, the development of atomic-resolution in-situ characterization techniques and first-principles computational models is crucial for establishing quantitative relationships between process parameters and atomic surface configurations. The results indicate that atomic-scale manufacturing must rely on multifield synergistic regulation combined with in-situ atomic-level monitoring and intelligent control to achieve precise process optimization and further advance ultraprecision manufacturing. Despite significant progress, several technical bottlenecks remain in achieving atomic-level polishing for SCD. First, multifield coupling mechanisms are yet to be fully understood, thus resulting in trade-offs between the material-removal rate and surface quality in mechanical polishing, as well as issues such as high equipment costs and instability in energy-beam polishing. Additionally, multifield coupling techniques present challenges such as dynamic parameter mismatches (e.g., pH fluctuations and uneven light distributions), thus hindering stable and efficient processing. Second, intelligent control systems for polishing processes remain underdeveloped, with limited real-time optimization capabilities and insufficient integration of smart algorithms with in-situ characterization techniques. This results in a trial-and-error approach for process optimization. Third, the industrialization of green and efficient processes is hampered by key obstacles such as high energy consumption, environmental risks, and low process repeatability, which pose significant constraints for large-scale applications. Hence, future research should focus on three key directions: (1) deepening the understanding of multifield coupling mechanisms, including the interactions between mechanical forces, chemical etching, and energy fields (e.g., light, sound, and plasma), and establishing quantitative models of parameter synergy; (2) advancing intelligent control technologies, such as machine learning-based algorithms for real-time process optimization, and developing high-precision multifield coupling equipment to enhance process stability and consistency; and (3) promoting green and efficient processes, including the development of environmentally friendly chemical systems and energy-saving machining methods, as well as establishing standardized protocols for industrial implementation. The key innovation of this study is its systematic evaluation of polishing technologies and the identification of critical research directions to overcome diamond-machining challenges. By comprehensively assessing the strengths and limitations of existing methods, this study provides a solid foundation for the development of next-generation diamond-based ICs as well as offers valuable insights for academic researchers and industry professionals in advanced semiconductor manufacturing.

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.

Novel intelligent lubricating materials and surfaces exhibit on-demand responsiveness and adaptability. The biomimetic self-regulating mechanism empowers in-service tribo-pairs with the autonomy to sense external environmental stimuli and adaptively modulate interfacial lubrication states. Such capabilities provide a groundbreaking solution for the “online sensing-decision-execution” intelligent transformation of advanced equipment in aerospace and defense sectors. Concurrently, the AI-driven intelligent inverse design of lubricating materials has revolutionized the traditional trial-and-error paradigm, enabling highly efficient and demand-responsive customization of lubrication for mechanical interfaces. This innovation provides a novel pathway for establishing a scientific framework for high-performance and high-reliability lubrication materials and surface systems capable of addressing diverse complex operational conditions. The intelligent evolution of lubricating materials and surfaces is progressively redefining the research paradigms in mechanical interface science, potentially unlocking breakthrough opportunities to advance frontier tribological theories and technologies. This paper discusses current research on self-lubricating, self-repairing, and self-diagnosing intelligent lubricating materials and surfaces, the frontier progress of AI-accelerated inverse design, and their future development trends, taking intelligent lubricating materials and surfaces and their AI paradigms as the pointcut. Currently, self-lubricating tribo-pairs that are environmentally robust and operationally adaptable use solid lubricating materials as the matrix, with liquid or solid-liquid-coupled lubricants as the dispersed phase. Effectively enhancing the interfacial lubrication performance can be achieved by releasing trace liquid lubricants to form fluid or boundary films. Two primary approaches are used for incorporating liquid lubricants into a tribo-pair matrix: porous-based self-storing and lubricating strategies and capsule-based self-storing and lubricating strategies. The development of capsule-based self-storage and lubrication techniques makes it a novel solid superlubrication method after carbon-based superlubrication and two-dimensional material superlubrication. This method enables macroscopic superlubrication at temperatures between 0 and 250 ℃. Although intelligent capsule-based self-storing and lubricating technologies can significantly reduce friction and wear on tribo-pair surfaces, material degradation and surface damage are inevitable during prolonged service. It is important to promptly repair wear and damage to improve the wear resistance and service life of tribo-pair materials. Intelligent surface healing technologies for tribo-pairs can be broadly categorized into extrinsic and intrinsic types. Extrinsic repair typically employs stimulus-responsive materials (for example, microcapsules or microvascular networks) to encapsulate active repair agents that are autonomously released upon external stimulus-induced damage, thereby facilitating physicochemical reactions for localized repair. Intrinsic repair leverages the reversible reorganization of dynamic covalent bonds (for example, Diels-Alder (DA) bonds, acylhydrazone bonds, and disulfide bonds) or non-covalent interactions (for example, hydrogen bonds, metal-ligand coordination, and host-guest interactions) to enable autonomous damage repair. Moreover, excessive wear on tribo-pair surfaces generates clearance, and its enlargement exacerbates vibration during equipment operation and reduces service life. Thus, it is imperative to endow tribo-pairs with self-diagnostic capabilities for real-time monitoring of wear locations and damage severity, enabling intelligent lifecycle management and predictive maintenance of equipment. Three approaches are the primary focus of the current intelligent self-diagnostic technologies: dye-based chromatic detection, electrical signal diagnostics, and optical signal diagnostics. The latest paradigm in the research and development of lubricating materials and surfaces, driven by AI, is the fourth paradigm after empirical, theoretical, and computational science paradigms. The primary technical approach involves employing machine-learning models to establish potential mapping relationships between the properties (such as composition and structure) of lubricant materials and surfaces and their lubrication performance. This enables prediction of the lubrication performance of new materials and surfaces. Furthermore, by integrating optimization algorithms or deep-reinforcement-learning techniques, global optimization within the high-dimensional nonlinear design space of lubricant materials and surfaces can be achieved rapidly, thereby facilitating the efficient inverse design of materials and surfaces with target attributes. This transformative research paradigm is expected to decipher the lubrication and friction reduction mechanisms at mechanical interfaces, overcome the efficiency limitations of traditional trial-and-error iterative methods, and ultimately realize demand-driven customization of lubricant materials and surface designs.

As the cornerstone of the digital economy, chips are advancing toward integration, low power consumption, intelligence, and functionality. Chemical-mechanical polishing (CMP) has become a critical technology for achieving ultrasmooth and defect-free global and local planarization in chip manufacturing. The abrasives in polishing slurry act as a “bridge” to facilitate the synergistic mechanical and chemical processes that are essential for high-precision material removal. Moreover, abrasives play crucial roles in achieving efficient, atomic-level, and smooth manufacturing of various materials, and they have become focal points of CMP research. Over the past few years, extensive efforts have been devoted to developing high-performance abrasives for chip manufacturing. In addition to being integral to the mechanical aspects of CMP, where they perform the physical removal of materials, abrasives also contribute chemically by interacting with the materials being polished. Hence, CMP performance is significantly influenced by the properties of the abrasives, including their dispersion stability, mechanical properties, morphology, particle size, and chemical reactivity. Maintaining the dispersion stability of abrasives is vital for prolonging the shelf lives of polishing slurries and minimizing defects, such as scratches. Furthermore, precise control over the morphology and size distribution of the abrasives can significantly reduce scratches on polished surfaces. Chemically reactive abrasives enable efficient material removal, which improves the overall polishing rate and surface quality. The research progress on typical abrasives used in CMP for semiconductor manufacturing is reviewed, with a focus on materials such as SiO₂, Al₂O₃, CeO₂, and diamond. SiO₂ abrasives are especially renowned for their abilities to satisfy the ultra-high-precision surface quality requirements of advanced semiconductor devices as well as their versatility across a wide range of materials and processing conditions. SiO₂ abrasives are essential for the manufacturing of modern electronics, particularly for applications that require exceptionally smooth and defect-free surfaces. Al₂O₃ abrasives are widely used in the CMP of substrates such as SiC, GaN, and sapphire, and they contribute to a favorable balance between performance and cost. CeO₂ abrasives are highly effective for achieving efficient material removal and fine surface finishes owing to their unique combination of mechanical hardness and chemical reactivity, which makes them ideal for specialized CMP applications. Diamond abrasives are essential for planarizing ultra-hard materials, including diamonds and other hard substrates, for which conventional abrasives are ineffective. In addition to these conventional abrasives, there is growing interest in novel abrasives and the integration of energy-field-assisted polishing techniques. These techniques utilize external energy fields (such as electric, magnetic, or optical fields) to enhance the physical and chemical interactions between abrasives and substrates, thus helping overcome the limitations of conventional abrasives when working with hard or chemically inert materials by providing an additional energy input. Moreover, there is ongoing research on the behavior of abrasives at the nanoscale, as semiconductor manufacturing is advancing toward smaller and more complex devices. Advanced characterization techniques and computational simulations were also used to gain a deeper understanding of the CMP process at the nanoscale, with the aim of understanding the atomic-level interactions between abrasives and substrates. Improving the precision and efficiency of the CMP processes is crucial, particularly for the production of next-generation semiconductor devices. Additionally, a forward-looking outlook on the application of abrasives in chip CMP is provided, and the needs for continued process optimization and the development of novel abrasives are emphasized. Furthermore, the theoretical mechanisms that govern CMP behavior must continue to be explored, as this will provide a strong foundation for future innovation in the field. This study aims to provide valuable insights and theoretical support to guide future research and development in CMP for the purpose of ultimately driving advancements in semiconductor manufacturing technology.

Chemical mechanical polishing (CMP) is a pivotal process in advanced semiconductor manufacturing that enables wafer surface planarization. CMP endpoint detection (EPD) technology achieves precise control over the wafer surface topography and material removal rates by dynamically adjusting the polishing pressure in different zones through real-time measurements of the thin film thickness. However, current EPD techniques face challenges in accurately capturing material removal rate variations in localized regions of wafers with complex patterns and nonuniform density distributions, leading to discrepancies between the detection signals and actual polishing states. Moreover, polishing processes involving multi-material systems suffer from limited signal resolution and selectivity, making it difficult to precisely detect interface changes. Thus, the investigation and optimization of CMP EPD technologies are crucial for addressing the challenges posed by multi-material and novel structures and improving the precision and stability of the process. This paper systematically reviews the current research on CMP EPD technologies, focusing on the principles, characteristics, and advancements in offline (e.g., the time method) and online (e.g., friction-based, optical, and eddy-current techniques) detection methods. In the early or stable stages of the CMP processes, endpoint control relies predominantly on experience and time-based polishing and lacks precise online detection. With technological advancements, four-probe offline detection instruments have been employed for post-polishing evaluations. However, these methods require extensive data accumulation and an understanding of the process parameters to determine the optimal polishing time for each material and process. Advanced CMP processes involve diverse materials, such as shallow trench isolation, interlayer dielectrics (SiO₂), metal interconnects (Cu), and barrier layers (Ti / TiN), each with distinct polishing rates and removal mechanisms. Offline detection methods struggle to adapt to these variations in real-time. In addition, time-based offline detection fails to account for wafer-to-wafer differences, rendering it insufficient to meet the demands of advanced CMP processes for real-time monitoring and rapid response. Consequently, online detection methods are often required to ensure process stability and product quality. Online EPD technologies enable real-time monitoring and analysis of polishing conditions during the CMP process, ensuring the achievement of the desired endpoints. These technologies are pivotal for automating the polishing process and enhancing the integrated circuit yield. Friction-based online EPD techniques offer strong real-time performance and ease of integration, making them particularly suitable for capturing dynamic mechanical interactions during polishing. However, these methods are significantly influenced by process conditions, such as pad wear and slurry flow, with signal noise and external disturbances undermining the detection accuracy and reliability. Future advancements in friction-based EPD should include the introduction of adaptive calibration mechanisms to mitigate external disturbances and the development of high-sensitivity friction sensors to explore the nanoscale film removal characteristics and meet the requirements of advanced process nodes. Optical EPD techniques typically achieve sub-nanometer resolutions for film thickness measurements. However, optical methods are highly sensitive to environmental conditions, with polishing slurry, debris, and surface contamination potentially interfering with signals and reducing detection precision. Future improvements in optical EPD systems should focus on enhancing the optical system design to resist interference from slurry, contaminants, and environmental fluctuations. Eddy-current EPD provides nanometer-level thickness measurements at a relatively low cost and can be easily integrated with CMP equipment. However, its insensitivity to insulating materials, such as dielectric layers, limits its ability to independently detect dielectric and nonmetallic films. Furthermore, the development of eddy-current sensors capable of achieving high-precision (nano- / sub-nanometer scale) measurements under large lift-off variations remains critical for future research. In the future, multi-physics field fusion methods will play a pivotal role in enhancing the detection performance to address the challenges posed by multilayer film stacks and heterogeneous material systems in 3D devices for advanced process nodes. By integrating optical, eddy-current, and friction-based techniques with multi-sensor collaborative acquisition and data fusion algorithms, the selectivity and accuracy of EPD can be significantly improved. Furthermore, AI-driven intelligent signal processing equipped with robust feature learning, pattern recognition, and intelligent decision-making capabilities enables the analysis and prediction of complex three-dimensional structural signals while adaptively adjusting the parameters, thereby enhancing the adaptability of EPD technologies. Additionally, flexible and customizable sensor designs combined with micro-area detection techniques contribute to increased spatiotemporal resolution, facilitating the precise monitoring and dynamic regulation of localized polishing conditions.

Laser-directed energy deposition (LDED) is a prominent technology in laser additive manufacturing and is known for its ability to enable the fabrication of complex, high-performance components layer by layer. The high-energy laser beam melts the substrate material, and the powder feeder simultaneously conveys the metal powder into the melt pool to deposit and solidify materials in a controlled manner into the required components The melt-pool temperature is crucial in determining the quality of the final component because it affects the microstructure, mechanical properties, and overall morphology of the deposition. During LDED, the temperature of the melt pool fluctuates owing to several variables, including changes in heat dissipation from the component, external environmental conditions, and equipment variations. These temperature fluctuations can result in defects such as unsatisfactory bonding, distorted geometry, or inconsistent material properties in the final component. Therefore, precise and real-time monitoring of the melt-pool temperature is essential to ensure that the deposition process remains within the optimal operating conditions, thus guaranteeing high-quality component production. The core challenge with LDED is the precise measurement and control of the melt-pool temperature. Measuring temperature directly is challenging owing to the dynamic and high-temperature nature of the melt pool, and conventional temperature-measurement methods may not be applicable or sufficiently precise in such environments. Hence, a color charge-coupled device coaxial temperature-measurement system is developed. This system allows real-time detection of the temperature distribution in the melt pool and provides important data for regulating the process parameters and maintaining the desired temperature profile during deposition. Several factors can affect the melt-pool temperature during LDED, including the powder feed rate, scanning speed, and laser power. A high laser power results in more melting and increases the melt-pool temperature, whereas lower power levels can lower the temperature and result in incomplete melting. Similarly, fluctuations in the powder feed rate and scanning speed can further affect the thermal conditions of the melt pool, thus resulting in temperature changes that may require real-time adjustments. To manage these temperature fluctuations and maintain a consistent process control, a closed-loop control system is required. In this study, an incremental fuzzy proportional-integral-derivative (PID) control algorithm is proposed to effectively control the melt-pool temperature. Fuzzy logic integrated into the PID control algorithm can address the nonlinear and uncertain aspects of LDED. It allows the control system to adapt to fluctuations and disturbances more effectively than conventional PID control methods. Simulink is used to develop a melt-pool temperature control simulation system that provides a theoretical framework to support the control-system design. The simulation allows various process parameters to be tested and the response of the control system to be evaluated under different operating conditions. The effectiveness of the control algorithm is verified through practical experiments, in which the laser power and powder feed rate are adjusted to simulate potential challenges in actual production scenarios. The results show that the fuzzy incremental PID algorithm performs better than the standard incremental PID algorithm, reduces the overshoot and steady-state errors, and improves the overall response time in a dynamic environment. This study contributes to the advancement of LDED technology by providing a novel approach for controlling the melt-pool temperature. By incorporating fuzzy logic into the PID algorithm, the system can manage the complex and nonlinear nature of LDED more accurately, thus ensuring consistent component quality and reducing the risk of defects. The closed-loop control system developed in this study has significant potential for real-world applications, as well as provides a robust solution for addressing temperature fluctuations and improving the reliability of laser additive-manufacturing processes.

Thermal barrier coatings (TBCs) technology has been widely employed in the thermal protection of aero-engine blades. The blade surfaces are coated with ceramic materials that exhibit excellent thermophysical properties, high-temperature stability, mechanical strength, and resistance to high-temperature corrosion, thereby ensuring the longevity of aero-engines. However, the traditional 6wt.%-8wt.% Y₂O₃-stabilized ZrO₂ (YSZ), commonly used to prepare TBCs, undergoes a phase transition with severe volume expansion, rapid sintering and severe high-temperature melt corrosion above 1 200 ℃, leading to premature coating failure. To address the increasing service temperature of high-performance aero-engine, developing the novel TBCs material is urgently required. Recent advancements in research of ‘high-entropy' alloys have inspired the application of the composition design of novel ceramic materials. The synthesis and performance evaluation of high-entropy ceramic materials have thus provided new avenues for the development of novel TBC materials. The outstanding performance of the high-entropy ceramic materials is primarily attributed to four inherent effects: ① thermodynamically high-entropy effect; ② dynamically sluggish diffusion effect; ③ severe lattice distortion; ④ cocktail effect. Relevant studies have demonstrated that these four distinctive effects associated with high-entropy materials provide a degree of flexibility in composition design and property regulation, which is not present in traditional TBCs or single-component TBCs materials. Furthermore, the comprehensive performance of high-entropy TBCs ceramics is comparatively better, as evidenced reduced thermal conductivity, a coefficient of thermal expansion (CTE) that is well-matched with the alloy substrate, and the exceptional high-temperature stability. This paper presents a summary of the current research status of high-entropy thermal barrier ceramics offering an analysis of component design and performance optimization based on the characteristics and the nature of bonding in the crystal structure. The analysis covers five key aspects: thermal conductivity, thermal expansion performance, high-temperature resistance to sintering and phase stability, mechanical properties and resistance to high-temperature CaO-MgO-Al₂O₃-SiO₂ CMAS corrosion. Elements with large mass disorder and ionic radius disorder are used for the synthesis of high-entropy TBCs materials to form a larger degree of lattice distortion, which can expand the phonon collision chances, decreasing the phonon mean free path and reducing the thermal conductivity. Anions and cations with minor differences in electronegativity can form ionic bonds with weak bonding strengths to obtain materials with higher CTE. Similarly, the formation of ionic bonds with strong bonding strength is beneficial for improving the mechanical properties, such as hardness and fracture toughness. The ions with the large radius difference compete for the same lattice site together, forming a more severe lattice distortion, which hinders matter diffusion. It leads to the sluggish diffusion phenomenon that contributes to high temperature stability. The concept of high entropy, based on the nature of multi-component single-phase solid solutions, offers a novel approach to the composition design and property regulation of novel TBCs materials, which has attracted considerable research interest. By summarizing and analyzing the radius disorder, mass order, and bond strength, the high-entropy thermal barrier ceramics with optimized composition based on the nature of ion can exhibit enhanced thermal physical properties, CTE, mechanical properties, high-temperature resistance to sintering and phase stability, and resistance to CMAS corrosion, exhibiting the potential for further development. However, the preparation and performance of high-entropy thermal barrier ceramic materials is the research mainstream, which is not entirely applicable. Moreover, several problems need further research and to provide solutions during manufacturing, thereby promoting its development and maturity, such as element segregation and phase transition. In this study, the theoretical guidance on the composition, design, performance optimization, and regulation of high-entropy TBCs materials and an outlook on the prospective applications is offered.

The accelerated development of modern industry and information technology has resulted in a notable surge in demand for high-performance materials capable of functioning in extreme environments, particularly in the domains of friction and electromagnetic wave absorption. MXene-based materials have attracted considerable interest owing to their exceptional properties, including high electrical conductivity, a unique layered structure, outstanding mechanical properties, chemical stability, and abundant surface functional groups. However, a comprehensive and systematic review of recent progress in the application of MXene-based materials in tribology and electromagnetic wave absorption remains unavailable. To address this gap, an in-depth and systematic review of the structural properties, preparation methods, and performance mechanisms of MXene-based materials in these applications is presented. The fundamental structural characteristics of MXene are examined, including its two-dimensional configuration, chemical composition, and surface modifications. These attributes are considered to be critical in understanding the multifunctional performance of MXene. Furthermore, the intrinsic properties of MXene, including its exceptional electrical conductivity and mechanical flexibility, are analyzed in detail. The preparation and processing techniques of MXene and its derivatives are also explored, with a focus on the ways in which various processes, ranging from conventional wet chemical etching to advanced composite fabrication methods, are employed to tailor MXene materials for specific performance requirements. In the field of tribology, MXene-based materials have the potential to significantly reduce friction and enhance wear resistance. The preparation and processing of MXene has been the subject of considerable study, and the results have highlighted notable advantages over traditional two-dimensional materials, such as graphene and molybdenum disulfide. In particular, the achievement of lower coefficients of friction and wear rates has been demonstrated. These superior tribological properties are primarily attributed to the unique two-dimensional structure and surface chemistry of MXene. The integration of MXene into lubricants or composites has been demonstrated to enhance friction reduction and anti-wear performance, yielding coefficients of friction and wear rates that exceed those of conventional materials. Furthermore, MXene functions effectively as a cross-linking agent in polymer systems, significantly improving their tribological characteristics by reinforcing their mechanical integrity and enhancing surface interactions. In the field of electromagnetic wave absorption, MXene-based materials demonstrate exceptional wave energy attenuation capabilities, attributable to their high electrical conductivity, superior dielectric loss, and tunable surface chemistry. These properties facilitate the efficient conversion of electromagnetic energy into other forms of energy, enabling optimal absorption performance across a wide frequency range. The surface functionalization and formation of composites with materials such as polymers, magnetic nanoparticles, or carbon-based structures have further enhanced the efficiency and bandwidth of the absorption process. Furthermore, the layered structure of MXene facilitates multiple internal reflections of electromagnetic waves, thereby significantly enhancing its absorption capabilities. A comparative analysis of various composite designs and processing techniques demonstrates that MXene-based materials outperform traditional wave-absorbing materials, such as ferrite and carbonyl iron powders, particularly in lightweight and flexible applications. These advantages position MXene-based materials as a highly promising solution for modern electronic devices, stealth technology, and electromagnetic interference shielding, addressing critical demands in these advanced technological fields. Despite the remarkable properties and potential of MXene-based materials across a range of applications, a number of challenges remain. These include stability issues under extreme conditions, such as limited resistance to oxidation and thermal degradation, as well as the complexity involved in designing multifunctional composites and the high costs associated with large-scale production. To overcome these obstacles, several improvement strategies are proposed. These include surface functionalization to enhance environmental stability, the integration of MXene with other nanomaterials to augment multifunctionality, and the optimization of preparation processes to reduce production costs. The implementation of these strategies is expected to significantly broaden the practical applications of MXene-based materials, thereby rendering them more feasible for industrial and technological use. In conclusion, the present study offers a systematic review of the research progress on MXene-based materials in the fields of tribology and electromagnetic wave absorption. This includes a detailed analysis of their unique properties, underlying mechanisms, and preparation methods. The findings provide a comprehensive understanding of the current advancements while identifying critical challenges and future research directions. Given their exceptional performance characteristics and versatile potential, MXene-based materials are anticipated to play a pivotal role in addressing the demands of modern industry and advanced technologies. It is likely that their continued development will yield innovative solutions for applications in high-performance friction materials, electromagnetic interference shielding, and beyond, underscoring their importance as a transformative material platform.

Marine biofouling poses a persistent challenge for submerged mechanical equipment, leading to accelerated corrosion, operational inefficiencies, and significant economic losses. The accumulation of microbial communities on marine surfaces not only damages equipment but also substantially increases maintenance costs, creating a critical bottleneck for sustainable marine resource development. Addressing this issue through effective antifouling solutions has become a global research priority in marine engineering. Current antifouling technologies primarily encompass mechanical removal, ultrasonic cleaning, and protective coatings, with antifouling coatings emerging as the most widely adopted solution due to their cost-effectiveness, ease of application, and superior performance. There is a wide variety of antifouling coatings, each with distinct antifouling mechanisms. However, comprehensive reviews on the antifouling performance, advantages, and disadvantages of both traditional and novel antifouling coatings remain scarce. Thus, a comprehensive review is conducted on the research advancements of both traditional and novel antifouling coatings, such as natural antifoulant coatings, biomimetic coatings, self-healing coatings, etc. Their research status, antifouling mechanisms, and remaining challenges are discussed. Traditional antifouling coatings can be categorized into matrix-insoluble and matrix-soluble types. The former operate through the gradual release of embedded biocidal compounds that deter or eliminate fouling organisms. However, these coatings exhibit significant limitations, including short service lifetimes and complex application requirements, which restrict their widespread adoption in marine applications. Self-polishing antifouling coatings (SPCs), the most currently commercially successful matrix-soluble system, dominating 90% of the global market, utilize hydrolyzable polymer side chains to enable controlled antifoulant release. However, their uneven release kinetics (initial excess followed by insufficiency) compromises long-term performance, and their dependence on toxic biocides raises environmental concerns. In contrast to these traditional coatings that rely on biocidal agents, fouling-release coatings achieve antifouling effects solely through their low surface energy, preventing fouling organisms from firmly adhering. Under water flow, fouling organisms detach easily, providing excellent antifouling performance without harming the marine environment. However, these coatings perform poorly under static conditions, and their adhesion to substrate needs improvement. Natural antifoulant coatings derive their active substances from antifouling compounds secreted by plants and animals or their synthetic analogs. They reduce marine biofouling by inhibiting adhesion processes and interfering with microbial signaling systems. Compared to traditional antifoulants, natural antifoulants are less toxic and significantly reduce environmental impact. However, challenges such as broad-spectrum efficacy and long-term durability remain unresolved. Biomimetic coatings utilize micro- and nanostructures from self-cleaning natural surfaces (via 3D printing, laser etching, or transfer techniques) to achieve efficient and eco-friendly antifouling effects, showing high application potential. However, these coatings often suffer from low mechanical strength, poor adaptability, and high production costs. Self-healing marine coatings integrate specialized repair agents that autonomously mend surface damage, overcoming key limitations of conventional systems by extending service life and maintaining antifouling efficacy. Despite their potential for significant economic and performance benefits, commercialization challenges persist, including complex fabrication, high costs, and difficulties in scaling beyond laboratory prototypes. Photocatalytic coatings rely on photocatalysts to undergo redox reactions under specific light wavelengths, decomposing seawater and dissolved oxygen to generate reactive oxygen species (ROS). These ROS penetrate cell membranes, damage microbial DNA, and cause cell rupture, achieving antifouling through microbial inactivation. These coatings are safe, efficient, non-toxic, and pollution-free. However, their performance is highly dependent on UV intensity and light energy utilization, requiring further improvements in stability. Hydrogel coatings contain high water content (typically >70%, even >90%), forming a dense and dynamic hydration layer through hydrogen bonding between polymer chains and water molecules. This layer effectively blocks fouling organism attachment. However, their poor mechanical properties and weak adhesion limit broader applications. Despite the variety of marine antifouling coatings available, single mechanism approaches generally fail to meet the complex demands of marine environments, particularly regarding long-term efficacy, broad-spectrum performance, and environmental safety. To overcome these limitations, we propose the strategic integration of multiple antifouling mechanisms within hybrid coating systems. This synergistic approach aims to combine the advantages of different technologies while mitigating their individual weaknesses, paving the way for next-generation antifouling solutions that balance performance, durability, and ecological sustainability. The findings provide valuable insights for developing advanced marine coatings.

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.

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.

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.

As the dimensional scaling and functional integration of high-end semiconductor devices accelerate, ultra-precision finishing of substrates such as monocrystalline Si, SiC, AlN, Ga₂O₃, and GaN is now constrained by atomic-level accuracy targets; while this context motivates the field, the present review concentrates on what enables—and limits—atomic-level grinding (ALG) as a deterministic route for planarization and thinning of semiconductor wafers, synthesizing mechanism-level knowledge with process engineering practice to clarify how ALG governs surface integrity, subsurface damage (SSD), total thickness variation (TTV), and mid-spatial-frequency (MSF) errors that ultimately control device yield and performance. We first dissect material-removal mechanisms from the atomic to the mesoscale and explain how ductile-regime grinding can be stabilized by connecting lattice bonding, elastic-plastic anisotropy, fracture resistance, and tribochemistry with the thermomechanical fields at the tool-work interface: for Si, pressure-induced phase transformation and subsequent tribo-oxidation support ultra-smooth shearing of a metastable / altered layer; for SiC, amorphization under high contact stress combined with oxidation-assisted weakening suppresses brittle fracture and enables Å-level topographies; for III-N and ultra-wide-bandgap oxides (GaN, AlN, Ga₂O₃), defect-mediated shear coupled with chemistry- or field-assisted bond weakening—via alkaline or oxidative chemistries and hydration reactions—reduces the effective activation energy for interfacial slip. Across materials, we highlight controlling nondimensional groups, particularly the ratio of undeformed chip thickness to the critical depth for ductile removal, that demarcate transitions among brittle chipping, quasi-ductile ploughing, and true ductile cutting, yielding mechanism maps that relate abrasive size and morphology, contact pressure, temperature, and chemistry to SSD depth, residual stress, and roughness. Building on these mechanisms, we catalog processing strategies and system-integration choices that operationalize ALG at wafer scale: fixed-abrasive ultra-fine diamond grinding with electrolytic inprocess dressing (ELID), ultrasonic-vibration-assisted modes that lower effective cutting forces, and laser / thermal assistance that locally softens the surface to tip the balance toward plasticity; chemo-mechanical synergy using oxidants, complexants, and pH / redox control to form and continuously renew a weak interfacial layer that can be sheared at nanometric depths of cut; and co-design of tooling and kinematics—resin / metal / ceramic bonds, abrasive size distributions, wheel-topography conditioning, and path planning (spiral / raster with dwell control)—to suppress TTV and MSF on 200-300 mm wafers. We summarize robust process windows from successful reports—high wheel speed, low feed and depth to keep the undeformed chip thickness sub-critical, ultra-stiff low-runout spindles, temperature-stabilized machine / wafer stacks, and low-noise workholding to prevent chatter—while analyzing fluid chemistry as a lever that intersects with frictional heating and contact time to regulate altered-layer thickness and face-dependent removal selectivity. Metrology and control are treated as first-class topics: in-situ force / acoustic- emission / temperature sensing for contact-state identification; optical interferometry for shape and MSF; and XPS / TEM / Raman for altered-layer chemistry and SSD, all feeding model-based and data-driven control frameworks that span multiscale simulation (DFT / MD to continuum) for predicting critical depths and stress fields, physics-informed machine learning for tuning parameters to minimize SSD at target MRR, and digital twins that couple thermal-structural drift, wheel-wear evolution, and wafer geometry for adaptive compensation of TTV and edge roll-off. From this synthesis, we make explicit the principal challenges: robust suppression of brittle events on hard, chemically inert wafers without sacrificing throughput; quantitative control of SSD at tens of nanometers or less with verifiable, crystallographic-face-dependent selectivity; wafer-scale flatness and TTV control during thinning, including edge roll-off mitigation; MSF management induced by periodic wheel topography or path artifacts; tool wear, self-sharpening, and wheel-state observability; thermal and dynamic stability of large, low-stiffness wafer stacks; seamless integration with downstream CMP without re-introducing defects; and greener chemistries that maintain mechanochemical efficacy. Finally, we identify emerging directions likely to be most impactful: hybrid energy fields (ultrasonic / laser / plasma-assisted ALG) to expand the ductile window; closed-loop, sensor-rich control with real-time detection of critical-depth excursions; physics-guided AI for multi-objective optimization of roughness / SSD / MRR subject to throughput and sustainability constraints; micro- / nano-textured abrasive tools that engineer contact states and chip evacuation; and standardized protocols plus open datasets for cross-material benchmarking. Collectively, the review delivers mechanism maps, process-integration guidelines, and a research agenda aimed at deterministic attainment of sub-nanometer roughness and minimal SSD in semiconductor substrate grinding, offering theoretical insights and technical references to guide future advancements in atomic-level grinding for semiconductor manufacturing.

Additive manufacturing technology can realize the integral molding of complex components of ceramic materials, but defects exist, including the “step effect” multiphase distribution, and porosity on the surface of the components. Moreover, subsequent precision machining struggles to meet the urgent demand for high-performance silicon-carbide ceramic components for space optical detectors and semiconductor manufacturing equipment. Therefore, this study proposes a novel approach by which to repair surface defects in ceramic additive manufacturing using the chemical vapor deposition (CVD) of high-purity, high-density silicon carbide coatings. However, the proposed method still faces problems of interfacial bonding with the additive ceramic substrate and the growth pattern of the coating. Hence, the effects of the deposition temperature on the interfacial bonding, micromorphology, surface hardness, and machinability of chemical vapor-deposited silicon carbide on additive manufacturing ceramic surfaces were systematically investigated. This study used rapid laser prototyping and the silicone infiltration composite method to manufacture silicon carbide ceramic substrates and prepare silicon carbide coatings via chemical vapor deposition. The silicon carbide coatings were deposited at different temperatures of 1 200, 1 300, 1 400, and 1 500 ℃. The coatings were then deposited on the surfaces of ceramic substrates at the same temperature. The effects of the deposition temperature on the hardness, deposition efficiency, interfacial bonding, microstructure, and processability of the SiC surface coatings were systematically investigated using various techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), surface roughness measurements, micro-computed tomography (micro-CT), and scratch tests. The results showed that the hardness of the additively fabricated SiC ceramic was only 1 226 HV_0.5 before any coating was deposited, and the roughness after polishing was 1 980 nm. Because of the presence of multiple phases, the roughness was too high to achieve a mirror effect. At a deposition temperature of 1 200 ℃, a peak of free silicon (Si) appeared in the coating owing to the high precursor gas concentration. However, the temperature was insufficient to promote uniform surface deposition, which resulted in an apparently homogeneous deposition in which free Si atoms in the gas phase were deposited directly onto the substrate. As the deposition temperature increases, the deposition rate accelerates, and the critical nucleation radius of the new phase gradually increases. The critical nucleation free energy also increases, resulting in the formation of larger SiC grains. The Si-C bonds within these grains remained intact, contributing to the overall hardness. However, at an excessively high deposition temperature, pores begin to form between the grains, resulting in low density and high porosity of the substrate and coating. Despite these problems, the silicon carbide coatings deposited at all temperatures formed good bonds with additively fabricated ceramic substrates. Notably, as the deposition temperature reaches 1 400 ℃, the silicon in the substrate begins to evaporate, and defects and porosity appear on the substrate surface. These defects provide additional nucleation points for the coating, and the morphology of the coating at the interface becomes columnar. As the coating grows to a certain thickness, it transforms into a dense structure. The columnar crystals significantly enhance the bond strength of the coating and improve its surface workability, which reduces its roughness to 9.08 nm. After polishing, the coating exhibited a mirror-like finish at all deposition temperatures. Thus, this study demonstrates that the application of CVD SiC coatings can significantly improve the surface quality of additively manufactured ceramics. This approach provides a theoretical basis for engineering applications of high-performance ceramic components in advanced devices.

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.

K9 glass is widely used in aerospace, military, and optoelectronic applications owing to its high mechanical strength, exceptional wear resistance, superior optical transparency, and excellent thermal stability. However, as a typical hard-brittle material characterized by low fracture toughness, K9 glass is more prone to subsurface damage and crack formation during machining processes. Chemical mechanical polishing (CMP), which is recognized for its high processing efficiency, simplified equipment configuration, and cost-effectiveness, has been extensively adopted for the surface finishing of optical glasses and other hard-brittle materials. Cerium oxide (CeO₂) abrasives are widely used in the surface planarization of optical glasses owing to their unique chemical reactivity with silica. Moreover, their particle size distributions play critical roles in determining both the material removal rate and surface quality. To meet the stringent requirements for a high material removal rate and superior surface quality in K9 glass polishing, this study systematically investigated the effects of five distinct particle sizes of CeO₂ abrasives on the CMP performance of K9 glass, both individually and in hybrid configurations. To isolate and quantify the contributions of the chemical and mechanical actions of the abrasives, the chemical effects of the CeO₂ abrasives were suppressed via the hydrogen peroxide (H₂O₂) treatment of the polishing slurry. This approach enables the decomposition of the total removed material into three fundamental components: mechanical action, chemical action, and synergistic interactions. In conjunction with an surface analysis using X-ray photoelectron spectroscopy (XPS), the surface chemical properties of CeO₂ abrasives with varying particle sizes were systematically characterized to elucidate the material removal mechanisms of different CeO₂ abrasives during a polishing process. The results showed that the material removal rate of K9 glass initially increased and then decreased as the particle size of the single CeO₂ abrasive increased. In contrast, the surface roughness exhibited the opposite trend. A high material removal rate (99.53 nm / min) and low surface roughness (1.27 nm) were achieved at particle sizes of 50 and 300 nm, respectively. Moreover, the combination of CeO₂ abrasives with particle sizes of 50 and 300 nm significantly improved the removal rate of K9 glass. When the mass ratio of the combination was 1∶2, the K9 glass exhibited an excellent removal rate (121.72 nm / min) and surface roughness (1.24 nm). When H₂O₂-treated CeO₂ slurries were employed to suppress chemical interactions, neither mechanical abrasion from the polishing pad nor pure chemical action by abrasives contributes measurably to material removal. The pure mechanical action of abrasives achieved a relatively low material removal rate. Moreover, the ratio (K) of the pure mechanical removal rate to the total removal rate exhibited an increasing trend with an increase in abrasive particle size. Specifically, the values of the parameter K for abrasives with particle sizes of 20 nm and 1 μm were 3.32% and 18.9%, respectively. The results of a surface analysis via XPS revealed that the surface Ce³⁺ concentration decreased as the particle size of the CeO₂ abrasives increased. Specifically, the Ce³⁺ concentrations for abrasives with particle sizes of 20 nm and 1 μm were measured at 29.5% and 25.33%, respectively. In the chemical-mechanical polishing of K9 glass, the synergistic interaction between the chemical and mechanical actions of the CeO₂ abrasives served as the dominant material removal mechanism. Smaller CeO₂ abrasive particles exhibited stronger chemical activity, and the surface Ce³⁺ concentration significantly influenced the material removal rate. Mechanical action was an indispensable component of this process. In contrast, larger abrasive particles demonstrated weaker chemical effects but exhibited enhanced mechanical grinding capabilities. The hybrid abrasive system, which effectively combined the enhanced chemical reactivity of small particles with the superior mechanical grinding capability of large particles, significantly improved the polishing performance of K9 glass. These results provide valuable theoretical and practical insights for the development of advanced polishing slurries for the precision machining of K9 glass and other optical materials.

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.

Nanoprecision surface manufacturing technology has important applications in many high-tech fields, such as semiconductor photovoltaic and integrated circuit manufacturing. Chemical mechanical polishing (CMP), the most critical technology in ultraprecision surface manufacturing, guarantees and promotes the application and development of high-end technologies. Gallium arsenide (GaAs) is the most important second-generation semiconductor substrate, and it is widely used in microelectronics and optoelectronics. High-quality GaAs substrates require the absence of surface / subsurface damage, preservation of lattice integrity, and sub-nanometer level surface roughness. CMP is currently the most effective technology to achieve these requirements. As material removal in CMP is predominantly governed by tribochemical reactions, understanding these mechanisms is essential for enhancing the surface quality. In this study, the tribochemical removal mechanisms during CMP of GaAs were investigated by conducting nano-wear experiments using an atomic force microscope (AFM) equipped with a silicon dioxide (SiO₂) microsphere tip under acidic (pH ≈ 4), neutral (pH ≈ 7), and alkaline (pH ≈ 10) conditions. Material-removal regions were characterized using high-resolution transmission electron microscopy (TEM). Density functional theory (DFT) calculations were employed to elucidate the atomic removal mechanisms. The results indicate that material removal on the GaAs surface is the most severe in alkaline conditions, with removal depths and volumes being significantly higher compared with those in neutral and acidic conditions. Specifically, the material removal depths in the acidic, neutral, and alkaline conditions were approximately 9.4, 19.2, and 24.2 nm, respectively. Similarly, the material removal volume increased from 4.99×10⁶ nm³ in acidic conditions to 8.84×10⁶ nm³ in alkaline conditions. A TEM analysis revealed that the lattice structure in the material-removal regions remained intact, suggesting that tribochemical reactions dominated the removal process without causing significant damage to the underlying atomic structure. The significant change in the charge density at the GaAs / SiO₂ interface, as calculated by DFT, suggests the formation of Si-O-Ga bonds. Furthermore, interfacial charge transfer was the most pronounced in alkaline conditions, where OH^- ions promoted the formation of Si-O-Ga bond bridges and weakened Ga-As bonds, facilitating material removal. The calculations showed that the charge transfers in the subsurface region of GaAs were 0.032, 0.039, and 0.042 e / ų under acidic, neutral, and alkaline conditions, respectively. This increased charge transfer in alkaline conditions leads to a more significant weakening of the Ga-As bonds, making the material more susceptible to removal. Additionally, CMP experiments conducted under the same pH conditions confirmed that the surface roughness and material removal rate (MRR) were optimal in alkaline conditions. The surface roughness (Sa) values were approximately 3.61, 1.87, and 0.81 nm for acidic, neutral, and alkaline conditions, respectively. The MRR values followed a similar trend, with the highest rate observed in alkaline solutions (22.6 nm / min), compared with those in neutral (19.4 nm / min) and acidic (13.2 nm / min) conditions. This consistency between the nanowear experiments and CMP results underscores the importance of pH in controlling the tribochemical removal process. These findings suggest that the presence of OH^- ions in alkaline conditions enhances the formation of Si-O-Ga bonds and increases charge transfer at the GaAs / SiO₂ interface, leading to more efficient material removal. This study provides valuable insights into the pH-dependent tribochemical removal mechanisms during the CMP of GaAs, providing a foundation for optimizing CMP processes for other binary materials. The integration of single-abrasive material removal experiments based on AFM, TEM, and DFT calculations presents a comprehensive approach for understanding and improving CMP techniques for semiconductor materials. By elucidating the role of pH in the tribochemical removal process, this study contributes to the development of more efficient and precise CMP methods that ultimately enhance the performance of semiconductor devices.

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.

Aluminum-based intermetallic compounds are recognized for their excellent high-temperature mechanical properties, high resistance to oxidation and corrosion at elevated temperatures, and low density. These characteristics make them suitable for a broad range of applications, including protective coatings and structural components in aerospace and other industries. High-energy-beam additive manufacturing technologies, such as laser and electron beam melting processes, are effective for the rapid fabrication of complex metal structures. However, depositing aluminum-based intermetallic compounds remains challenging due to their complex phase structures and inherent brittleness, which often lead to flaws and defects, particularly cracks. Cold spraying, a process characterized by low processing temperatures and high deposition rates, shows significant potential for the low-heat-input fabrication of aluminum-based intermetallic compounds. This paper summarizes and analyzes recent advancements in the preparation of aluminum-based intermetallic compounds using cold spraying. Effects of powder design and fabrication routes on deposition behavior and deposit properties are discussed. These routes include intermetallic compound powder deposition, mixed elemental metal powder cold spraying followed by heat treatment, and cold spraying of mechanically ball-milled pseudo-alloy powders with subsequent heat treatment. First, the deposition behavior of intermetallic compound powders is reviewed and discussed. In the cold spraying process, successful deposition and bonding of spraying particles rely on plastic deformation induced by particle impact. However, due to the intrinsic brittleness of intermetallic compounds at room temperature, it is difficult to deposit particles directly using intermetallic compound powders as feedstock. In practice, when relatively soft materials are used, only a single layer of intermetallic particles can be mechanically embedded into the substrate layer. Subsequent spraying does not contribute to building up of the deposit because achieving successful bonding between intermetallic particles is highly challenging. Although high gas temperatures, even up to 1 000 ℃, are used to soften intermetallic particles, depositing a thick, high-quality deposit remains elusive. Thus, preparing intermetallic deposits using intermetallic feedstock powders continues to be a challenge. To address this issue, an alternative strategy involving the formation of intermetallic compounds during or after deposition has been extensively investigated. Following this strategy, mechanically mixed powders containing aluminum (Al) and other elemental powders, such as iron (Fe), nickel (Ni), or titanium (Ti), are used as feedstock materials. Due to the excellent plastic deformability of elemental metal powders, deposits containing mixed elemental metal particles can be easily deposited by cold spraying at relatively low gas temperatures and pressures. Post-spray heat treatment or annealing is then performed to activate interdiffusion between the Al and Fe / Ni / Ti phases, facilitating the formation of intermetallic compounds. However, the higher deposition efficiency of Al powder compared to Fe / Ni / Ti powders often results in cold-sprayed composite deposits with a higher Al content than the feedstock powder, complicating precise control of the chemical composition. This challenge is particularly pronounced when the feedstock powder contains more than three elemental metal powders. Additionally, during heat treatment, the long diffusion paths required for intermetallic compound formation frequently lead to the creation of numerous Kirkendall pores, and achieving a single intermetallic phase proves difficult. To overcome these challenges, a method involving the cold spraying of mechanically milled pseudo-alloy powders, followed by heat treatment, is proposed. By controlling the intensity and duration of high-energy ball milling, pseudo-alloy powders with alternating submicron lamellae of various metals can be prepared from mechanically mixed metal powders. The composition of the pseudo-alloy powder can be precisely controlled by adjusting the proportions of the raw materials. Moreover, the pseudo-alloy powder retains the plastic deformation capability of the original elemental metals, ensuring efficient deposition during cold spraying. The fine microstructure of the alternating submicron metal lamellae significantly shortens diffusion paths during heat treatment, effectively mitigating the formation of Kirkendall pores in the deposit. Finally, the effects of post-treatments such as friction stir processing (FSP) and hot isostatic pressing (HIP) on the microstructure and properties of the deposit are summarized. FSP treatment greatly refines the microstructure of deposits sprayed with mechanically mixed elemental metal powders, resulting in structures featuring alternating submicron metal lamellae and partially formed intermetallic compounds. This refinement significantly shortens diffusion paths between phases and prevents the formation of Kirkendall pores. However, it is challenging to process parts with complex shapes using this method. In contrast, HIP applies isostatic pressure during treatment, closing Kirkendall pores and making it suitable for parts with complex geometries. Overall, cold spraying of mechanically mixed elemental metal powders followed by HIP treatment, as well as cold spraying of mechanically milled powders combined with subsequent heat treatment, have been shown to produce aluminum-based intermetallic compounds with low porosity and high hardness. By comparing and analyzing the advantages and limitations of different technological routes, this study aims to provide guidance for the cold-spraying additive manufacturing of aluminum-based intermetallic compounds.

Titanium dioxide nanotubes (Titanium dioxide nanotubes, TiO₂ NTs) have garnered significant attention in recent years owing to their unique nanostructures, high specific surface areas, and exceptional antibacterial and drug-release capabilities. As innovative surface-modification materials, TiO₂ NTs show great promise for use in biomedical applications, particularly in infection control and drug delivery. The remarkable properties of TiO₂ NTs, including their abilities to interact with biological systems, have made them a focal point of research for the development of new therapeutic strategies, particularly for combating bacterial infections. This review systematically examines the fabrication methods of TiO₂ NTs and their applications in the antibacterial field, focusing on their roles in controlling bacterial infections and regulating drug release mechanisms. The methods used to fabricate TiO₂ NTs, such as anodization, sol-gel processes, and hydrothermal synthesis, are critical for controlling their size, morphology, and surface properties, all of which directly influence their performance in various biomedical applications. These fabrication techniques allow for precise control over nanotube structures, which optimizes their drug-loading capacity and ensures their effectiveness in both infection prevention and controlled drug release. Moreover, TiO₂ NTs are highly effective at preventing bacterial adhesion and biofilm formation, which are key challenges in medical treatments. Further, TiO₂ NTs can be functionalized by loading various antibacterial agents, such as antibiotics, silver nanoparticles, and other bioactive compounds, to enhance their therapeutic effects. This review discusses various loading techniques, including physical adsorption, layer-by-layer self-assembly, and solution impregnation, for improving the efficiency of drug delivery. Physical adsorption is a simple and widely used technique for loading antibacterial agents, where the agents are adsorbed onto the surfaces of nanotubes. In contrast, layer-by-layer self-assembly creates a more complex structure with multiple layers, thus allowing for a more controlled and sustained release of drugs. Solution impregnation, which is another important technique, facilitates the incorporation of therapeutic agents into nanotubes and ensures that the drugs are released gradually, thus enhancing their antibacterial effects over an extended period. Additionally, sealing technologies are crucial for enhancing the drug release efficiency. Sealing methods typically involve the use of polymers or composite materials that encapsulate drugs, which prevents their premature release and ensures a more controlled and sustained-release profile. These sealing technologies improve the stability and performance of TiO₂ NTs in biological environments and thereby optimize their therapeutic benefits. Despite the promising antibacterial properties and biocompatibility of TiO₂ NTs, their practical applications face several challenges. Issues such as the structural stability of TiO₂ NTs in biological environments, precision of drug release, and long-term safety must be addressed. The degradation and morphological changes in TiO₂ NTs in biological fluids can compromise their functionality and biocompatibility. Moreover, ensuring precise drug release is challenging because the careful design of the nanotube structure and loading methods are required. Long-term safety, particularly the potential toxicity of TiO₂ NTs and their degradation products, must be further evaluated to ensure their safe use in medical applications. Future research should focus on optimizing the design of TiO₂ NTs by exploring new fabrication techniques and developing multifunctional composite materials that combine TiO₂ NTs with other materials, such as polymers, natural biomolecules, or nanoparticles. These composite materials can enhance the stability and drug loading as well as control the release of TiO₂ NTs, which thereby expands their applications in a variety of therapeutic contexts. Furthermore, clinical trials are required to validate the long-term safety and efficacy of TiO₂ NTs in real-world medical applications. By addressing these challenges and advancing the development of TiO₂ NTs, their potential for widespread use in the medical field can be realized to thereby provide innovative solutions for infection prevention, controlled drug delivery, and other biomedical treatments.

The additive manufacturing of 316L stainless steel presents numerous advantages, such as high efficiency, the ability to create complex geometries via freeform fabrication, and superior mechanical and corrosion resistance properties. These characteristics establish a strong foundation for the integrated manufacturing of critical components used in diverse fields, including mining machinery, engineering equipment, hydraulic systems, and other applications that require a seamless blend of structural integrity and functional performance. Despite these benefits, the wear resistance of additively manufactured 316L stainless steel remains a significant challenge that hinders the broad applicability of 316L stainless steel in demanding environments. Ultrasonic severe surface rolling (USSR) is a promising nanocrystallization technology. This innovative technique can generate thick and uniform gradient surface layers while producing exceptionally smooth surfaces on metallic materials, including 316L stainless steel. Importantly, USSR is effective not only on flat surfaces but also on components with complex geometries, showing its potential to significantly enhance the wear resistance of additively manufactured parts. In this study, selective laser melting (SLM) was used to fabricate 316L stainless steel. The SLM was followed by USSR to improve the wear resistance of the 316L stainless steel. A comprehensive microstructural analysis was performed using transmission electron microscopy and electron backscatter diffraction to investigate the microstructural evolution induced by the USSR treatment. The results indicate that the USSR process induced a gradient heterogeneous structure within the surface layer of the SLM-fabricated 316L stainless steel. This gradient heterogeneous structure is characterized by a microstructural transformation from a homogeneous nanograined structure at the surface to a heterogeneous structure with increasing depth. The surface nanograined structure was composed of austenitic grains and a few martensitic grains with an average grain size of 87 nm. In contrast, the SLM-fabricated sample exhibited a heterogeneous structure composed of austenitic grains with a large average grain size of 27 μm. Linear reciprocating sliding tribological tests were conducted using a ball-on-flat plate configuration at room temperature to evaluate wear resistance under both dry friction and emulsion lubrication conditions. The findings reveal a substantial reduction in wear volume under dry friction. The wear volume for the SLM-fabricated sample decreases from 3.58×10^-2 mm³ to 1.90×10^-2 mm³ for the USSR-treated sample, representing a notable reduction of 46.93%. Similarly, under emulsion lubrication, the wear volume decreases from 4.74×10^-4 mm³ to 2.39×10^-4 mm³, representing a reduction of 49.58%. These results unequivocally demonstrate that the USSR method significantly enhances the wear resistance of SLM-fabricated 316L stainless steel. Additionally, microhardness measurements show a marked improvement in hardness, which increases from 237.83 HV to 442.27 HV, representing an impressive enhancement of 86%. Further characterization of the worn surface morphology was conducted using scanning electron microscopy and energy-dispersive X-ray spectroscopy to elucidate the underlying wear mechanisms. The results indicate that the USSR treatment did not fundamentally alter the wear mechanisms of the SLM-fabricated 316L stainless steel. Under dry friction conditions, the worn surface morphology is characterized by high concentrations of elemental oxygen along with visible grooves and pits, suggesting that oxidative wear, abrasive wear, and delamination are the predominant wear mechanisms. In contrast, under emulsion lubrication, the morphology exhibited grooves and pits, indicating that abrasive wear and delamination took precedence in this environment. The observed enhancement in wear resistance is primarily attributable to the increased hardness and deformation resistance resulting from the heterogeneous gradient structure established by the USSR treatment. These findings provide valuable insights and present a novel methodology for enhancing the wear resistance of additively manufactured 316L stainless steel and its associated components, thereby paving the way for its wider adoption in industrial applications. A typical application is the production of durable and highly reliable water-hydraulic components for use in mining machinery.

3D-printed silicon carbide (SiC) ceramics have excellent qualities such as high strength and temperature resistance and they permit flexible molding of complex shapes, leading to their wide use in energy processing and advanced aerospace applications in recent years. However, they have poor surface abrasion resistance. Using atmospheric plasma spraying (APS) is an economically feasible method for applying high-temperature abrasion-resistant coating on the surface of parts. Among the common self-lubricating wear-resistant coatings, YSZ coating, with its excellent high-temperature stability and oxidation resistance, is generally used in high-temperature environments. However, to improve the performance of the spraying process and reduce friction, a second phase is often added. This paper proposes (1) doping the coating with both low- and high-temperature lubricants to enable wide-temperature lubrication, (2) adding alumina to reduce the melting point of the powder and improve the coating densification, and (3) using a sol-gel-coated powder to improve the bonding between the base and second phases of the coating. In this study, three composite powders with different compositions of YSZ-Al₂O₃-CaF₂-C were prepared using the sol-gel method and centrifugal atomization drying. The corresponding composite coatings (Ca0C0, Ca5C10, and Ca10C5) were deposited on the surface of 3D-printed SiC ceramics using the APS technique. The microstructures, friction properties, and wear mechanisms of the composite coatings were studied at room temperature and 600 ℃. The results show that the coatings have a typical laminated structure. Both the coatings and abrasion marks were primarily composed of YSZ, Al₂O₃, and m-ZrO₂ phases, with CaF₂ and C phases in Ca10C5 and Ca5C10 coatings. No other chemical reactions occurred during the coating application or owing to friction. The Ca0C0 coatings without CaF₂ and C lubrication phases had the highest hardness, lowest wear rates, and largest friction factor at room temperature and 600 ℃. The strong bonding of the coating to the friction partner at 600 ℃ led to a friction coefficient of more than 1. The stabilized friction factor of Ca10C5 and Ca5C10 coatings were, respectively, 0.239 and 0.130 at room temperature and 0.175 and 0.288 at 600 ℃. The friction factor of Ca5C10 and Ca10C5 coatings considerably reduced upon the addition of CaF₂ and C lubrication phases at both room temperature and 600 ℃, reflecting improved self-lubricating properties. However, the addition of the lubrication phases led to a decrease in the hardness of the coatings and an increase in the porosity defects inside the coatings, accompanied by an increase in wear rate. The Ca5C10 coatings with higher C additions were more prone to abrasive debris generation because of the higher volume fraction of C and lower hardness, resulting in higher wear rates. Based on the abrasion mark morphology, the wear mechanism of the coating was concluded to be primarily adhesive and abrasive. The YSZ-10Al₂O₃-10CaF₂-5C coating had a lower friction factor and wear rate (1.02×10^-5 mm³ / (N·m) at room temperature and 0.84×10^-5 mm³ / (N·m) at 600 ℃) compared with YSZ-10Al₂O₃-0CaF₂-0C and YSZ-10Al₂O₃-5CaF₂-10C coatings in this study. This implies that YSZ-10Al₂O₃-10CaF₂-5C coating has good self-lubricating and wear-resistant properties and can well improve the surface properties of 3D-printed SiC.

In recent years, laser cladding for the preparation of high-entropy alloys (HEAs) has attracted widespread attention in aerospace, transportation, and marine applications. FeCoCrNi-series high-entropy alloys are among the most widely studied transition-metal HEAs. Due to their unique properties (i.e., high-entropy effect, lattice distortion effect, slow diffusion effect, and cocktail effect), FeCoCrNi-series entropy alloys can achieve synergistic improvement in strength and toughness. Many studies have confirmed that laser-cladding FeCoCrNiAlTi HEA coatings offer excellent mechanical properties, including high strength, toughness, corrosion resistance, and oxidation resistance at high-temperatures. However, there are currently few studies on the friction and wear mechanism of FeCoCrNiAlTi HEA coatings under corrosion-friction coupling, and the interaction between alloy elements, microstructure, wear, and corrosion resistance remains unclear. In this study, a FeCoCrNiAl_0.5Ti_0.5 HEA coating was prepared on an AISI 1045 steel substrate using laser-cladding technology. Dry and wet friction tests were performed on the coating and substrate immersed in the solution for different durations. The dry and wet friction was tested using a ball-on-disc wear test. After grinding and polishing, the microstructure of the sample surface was characterized, followed by corrosion in an aqua regia solution (75 mL HCl and 25 mL HNO₃ per 100 mL solution) for 30 s. The hardness pits of the sample and the transition from the coating to the substrate were observed via optical microscopy (OM). After the wear test, the depths and widths of the wear scars were measured using a three-dimensional profilometer. The microstructures and wear scar characteristics of the samples were characterized using a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectroscope (EDS) and an electron backscatter diffraction (EBSD) detector. The phase compositions of the powder and sample were characterized using X-ray diffraction (XRD). The dry and wet friction behaviors of the coating related to atmospheric and corrosive environments were investigated in combination with the friction and wear test results. The results indicated that the microstructure of the laser-cladded FeCoNiCrAl_0.5Ti_0.5 HEA coating mainly consisted of a dendrite region (DR) with a body-centered cubic (BCC) phase and an interdendritic region (IR) with a face-centered cubic (FCC) phase. In addition, under spinodal decomposition, a portion of the BCC phase in the lamellar eutectic structure of the coating transformed into the L2₁ phase. The laser-clad FeCoNiCrAl_0.5Ti_0.5 HEA coating demonstrated excellent wear resistance. The friction factor of HEA coating and the dry friction factor of AISI steel substrate were 0.69 and 0.75, respectively, with wear rates of 5.04×10^-5 mm³ / (N·m) and 1.41×10^-4 mm³ / (N·m), respectively. The immersion time in a 3.5wt.% NaCl solution significantly influenced the wet friction and wear properties of the laser-cladded FeCoNiCrAl_0.5Ti_0.5 HEA coating. The wet friction wear rate of the coating increased with the immersion time. The wet friction wear rate of the unimmersed coating was 1.11×10^-5 mm³ / (N·m), while that of the coating immersed for 15 days increased by 1.77 times, reaching 3.08×10^-5 mm³ / (N·m). The main forms of dry friction and wear of the laser-clad FeCoNiCrAl_0.5Ti_0.5 HEA coating were three-body wear and abrasive wear, whereas the wet friction wear process was affected by corrosion, oxidation wear, and three-body wear. The wet friction wear process is lubricated by water and oxide films between the friction pairs; therefore, the wear rate is significantly lower than that in dry friction. However, under wet friction conditions, the oxide film was easily corroded, leading to the formation of microcracks and film delamination, ultimately resulting in three-body wear.

With the progress of science and technology and improvements in living standards, the demand for electronic equipment has gradually changed from rigid and bulky to flexible and lightweight. Consequently, flexible electronic devices have become increasingly popular. Flexible wearable electronic devices are the development and innovation of flexible devices and have gained wide attention in the fields of healthcare, motion tracking, and environmental monitoring owing to their advantages such as light weight, portability, high integration, and good shape preservation. However, the long-term stability of wearable devices is challenged by their complex working environments, both from the external environment and secretions of human skin (rain, sweat, food residue, etc.). Inspired by the special biological surfaces in nature, the realization of special functions of materials or devices by regulating surface wettability has become a research hotspot. Surface wettability regulation has significant advantages for optimizing the design of solid-liquid interface interactions. Because liquid droplets can form spheres and quickly roll off, superhydrophobic surfaces have versatile functionalities such as waterproofing, self-cleaning, anti-corrosion, and antibacterial properties. This provides new opportunities to improve the performance and prolong the life of wearable electronic devices. For example, its excellent waterproof function can prevent external moisture intrusion, reduce the risk of short circuit and corrosion, and extend the service life, thus ensuring the stable operation of the device in wet environments. Self-cleaning and anti-contamination properties can keep the device clean, ensure accurate signal transmission and stable performance, eliminate the hassle of frequent cleaning, and improve the user experience. In addition, the superhydrophobic surface can reduce liquid accumulation, maintain device cleanliness, and improve comfort levels, laying the foundation for the wide application of superhydrophobic surfaces in flexible wearable electronics. This study focuses on the application of superhydrophobic surfaces in flexible wearable devices. First, the working principle of a superhydrophobic surface is introduced. The key to obtaining a superhydrophobic surface is to reduce the surface energy and increase the surface roughness. The preparation methods for superhydrophobic surfaces, including electrochemical deposition, electrospinning, chemical vapor deposition, and etching, are briefly described. This is followed by the application of superhydrophobic surfaces in flexible electronic devices. First, the application of superhydrophobic coatings in sensors is introduced. When a superhydrophobic coating is applied in the microchannel modification of a sweat sensor, the sweat transfer rate is significantly increased; thus, the sensing performance is improved. Superhydrophobic surfaces can provide sensors with moisture resistance, liquid resistance, self-cleaning, and weather resistance properties, significantly improving their service life. Second, the applications of superhydrophobic coatings in energy-conversion devices (such as nanogenerators) are described. Because the working principle of friction nanogenerators is to collect the electrostatic energy generated by contact charging, the waterproofing performance of the superhydrophobic coating helps friction nanogenerators collect more energy from the flowing water. Subsequently, the application of superhydrophobic coatings to energy-storage devices that provide energy support for flexible wearable electronic devices is introduced. Superhydrophobic coatings can significantly improve the safety and stability of energy storage devices. Although superhydrophobic coatings have certain applications, their service stability still faces challenges. Finally, it is pointed out that high mechanical stability, good environmental durability, and high light transmittance are challenges for the future development of superhydrophobic surfaces for wearable devices.

Ultraprecision surface grinding and polishing are crucial for manufacturing high-end aluminum nitride (AlN)-based wide-bandgap semiconductor chips and devices. When traditional ultra-precision surface processing methods such as nanogrinding are used to process AlN, the material removal rate is low, and processing-induced damage is difficult to control owing to the hard-brittle properties of AlN. It has been proven that inducing ultrasonic vibrations can increase the material removal rate and reduce subsurface damage during grinding. However, the material-removal mechanisms of ultrasonic vibration-assisted nanogrinding of AlN are not completely understood, and the influencing law and microscopic mechanisms of amplitude and frequency remain unclear. To this end, molecular dynamics simulations of ultrasonic vibration-assisted nanogrinding of AlN surfaces with single diamond abrasives under different conditions were performed to investigate the influence of amplitude and frequency on the removal of nanoscale / sub-nanoscale materials and subsurface lattice damage at the atomic level. The Vashishta potential function was used to describe the interatomic interactions within the AlN workpiece, and the Lennard-Jones potential function was used to describe the C-Al and C-N interactions between the diamond abrasives and the AlN workpiece. The microstructure of the AlN workpiece during nanogrinding was characterized by the dislocation extraction algorithm (DXA) and identify diamond structure (IDS) to discuss the effects of amplitude and frequency on subsurface lattice damage such as dislocations, stacking faults, and amorphization. Based on a comprehensive analysis of the data of the grinding force, grinding morphology, removal volume, subsurface microstructures, temperature distribution, and von Mises stress distribution, the mechanism of ultrasonic vibration-assisted nanogrinding under different amplitude and frequency conditions on the nanoscale / sub-nanoscale material removal and subsurface lattice damage at the atomic level was explored. The simulation results demonstrate that both amplitude and frequency significantly affect the grinding force, and the instantaneous tangential and normal contact areas between the diamond abrasives and AlN workpieces during nano-grinding are reduced with increasing amplitude or frequency, leading to a decrease in tangential and normal forces. Increasing the amplitude or frequency can significantly increase the material-removal volume, reduce the roughness of the grinding surface, and reduce the lattice damage in the subsurface. As the amplitude increases, the grinding force decreases linearly, the removal volume increases linearly, the dislocation distribution range decreases, and the material-removal behavior gradually changes from plastic-dominated to composite removal. When the vibration frequency reaches 1 GHz, the ultra-high-frequency vibration enhances the impact effect of the diamond abrasive on the AlN workpieces and causes the atoms to acquire high instantaneous energy, thus generating high-temperature zones at the abrasive-workpiece contact area. Owing to the more intense thermal activity of the atoms, the Al and N atoms linked via covalent bonds in these high-temperature zones can be broken more easily. Hence, material removal is facilitated, the grinding force decreases, and the removal volume increases sharply. The surface of the groove is smooth, almost reaching the atomic level of flatness, and the two sides of the groove show obvious atomic-laminar removal features. At this point, the subsurface obtains a state of almost no damage; that is, no dislocations or amorphous structures are formed except for slight stacking faults in the subsurface. In contrast, when the vibration frequencies are 10 and 100 MHz, the surface roughness is high, and many dislocations and stacking layers appear in the AlN workpiece. The analysis results suggest that ultrahigh-frequency vibration induces a localized temperature increase in the abrasive-workpiece contact area and enhances the impact of the abrasive. The research results can provide a theoretical reference for optimizing the process conditions for high-efficiency and low-damage ultraprecision grinding of hard-brittle semiconductor materials.

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.

The development of precision medicine requires efficient, stable, and multifunctional biomechanical interfaces. The abundant micro / nanostructures and functional mechanisms found in nature provide important inspiration for interface design; however, research on biomimetic bio-machine interfaces for precision medicine still lacks in-depth and systematic reviews. This paper systematically summarizes representative biomimetic strategies in interface design, with a particular focus on the principles and applications of antifouling, adhesion enhancement, directional liquid transport, and microneedle penetration structures in interface construction. It further discusses the advantages and limitations of advanced manufacturing technologies, such as laser processing and 3D printing, for the fabrication of multiscale biomimetic structures. Typical applications in precision medicine, including antifouling electrosurgical scalpels, adhesive patches, wearable microfluidic diagnostic sensors, and drug delivery systems, have demonstrated the remarkable benefits of biomimetic structures for improving interfacial adaptability, functional integration, and clinical applicability. Finally, this study explores the crucial role of emerging technologies, such as artificial intelligence, stimuli-responsive materials, and multi-material 3D printing, in driving the advancement of biomimetic bio-machine interfaces. Despite notable progress in biomimetic design and manufacturing, this field remains in its early stages and faces multiple challenges. For instance, natural multifunctional interfaces often exhibit highly complex material compositions and hierarchical multiscale features, making high-precision and consistent biomimetic reconstruction across the macro- and microscales highly dependent on breakthroughs in advanced manufacturing. Current biomimetic approaches are largely confined to isolated structural or material mimicry, with limited progress in the integrated codesign of structures, materials, and functions. Moreover, the intelligent responsiveness and multifunctional integration of interface systems remain underdeveloped, and achieving external-field-driven control (e.g., mechanical, thermal, acoustic, optical, electrical, and chemical) of interface properties is key to advancing system intelligence. Currently, most biomimetic functional interfaces remain in the proof-of-concept stage, and their long-term durability, biocompatibility, and safety require further validation for clinical and real-world applications. Biomechanical interfaces are expected to evolve beyond static designs to dynamic and adaptive systems. By integrating stimuli-responsive materials with flexible sensing networks, such interfaces can achieve real-time environmental perception and feedback regulation, enabling closed-loop intelligent medical devices, such as adaptive neural interfaces and dynamic drug-delivery microneedle arrays. Multiscale simulations (e.g., molecular dynamics and finite element analysis) can accurately predict the mechanical, electrical, and biological behaviors at the interface. Furthermore, coupling biomimetic design with artificial intelligence, particularly machine and deep learning, promises to establish data-driven platforms for interface design, enabling an integrated workflow from natural structure extraction and material selection to manufacturing pathway planning and performance prediction, thus advancing the paradigm from experience-driven to data-driven biomimetic design. Breakthroughs in key technologies such as multimaterial cooperative printing and scalable micro / nanoscale manufacturing are critical for establishing standardized and modular fabrication systems with improved reproducibility and consistency. Simultaneously, systematic frameworks for long-term biocompatibility assessment must be developed to ensure clinical safety and stability. In summary, this study proposes two guiding strategies—dynamic biomimetic design enabled by smart materials and intelligent interface design enabled by artificial intelligence—to fill a critical gap in the literature. These perspectives provide valuable insights for the future development of biomimetic interface design and manufacturing for precision medicine.

In the context of the national strategy for “Maritime power” and the construction of the “Belt and Road”, marine engineering infrastructure construction of China has accelerated. The on-site use of raw materials such as coral and seawater to prepare marine concrete (MC) significantly reduces project costs, ensures the construction period, and reduces carbon emissions due to transportation. However, complex and harsh marine environments have a strong corrosive and destructive effect on structures, seriously affecting the use and safety of marine engineering structures. Therefore, it is of great significance to apply additional anticorrosion measures to MC structures and conduct research on service life prediction and durability design. In marine environments, the corrosion of steel bars inside concrete structures caused by chloride ions in seawater is a main reason for the deterioration in the durability of these structures. In this study, to effectively improve the durability of concrete structures in marine engineering, it was treated with two anti-corrosion measures: internal addition of composite active mineral admixtures (MA) and external application of high-permeability epoxy protective materials (SP). By investigating the diffusion law of Cl^- in concrete, the effects of thicknesses of concrete protective layers, concrete types, strength grades, exposed areas, and additional anti-corrosion measures on the service life of coral aggregate concrete (CAC) and ordinary aggregate concrete (OAC) structures were studied. Design suggestions for improving the service life of MC structures were proposed based on the ChaDuraLife life prediction method, which combines the characteristics of the exposed environment of concrete structures in marine engineering. Theoretical and data support are provided for the application of MC in practical engineering. The results showed that under the same marine exposure zone, with an increase in the concrete strength grade and protective layer thickness, the service life of the CAC and OAC structures gradually increased. The service life of the OAC structures exhibited the trend of underwater zone > atmospheric zone > tidal zone in different ocean exposure areas. When the concrete strength grade, protective layer thickness, and exposure zone were the same, the service life of CAC structures was shorter than that of OAC and followed the pattern of atmospheric zone > underwater zone > tidal zone. The use of internally mixed composite mineral admixture MA, externally coated high-permeability epoxy protective material SP, and “internally mixed + externally coated” anti-corrosion measures increased the service life of OAC structures by 1.8/1.7, 2.4/2.4, and 3.4/3.2 times, respectively, compared with no measures. In underwater zone of the ocean, for CAC/OAC structures with a conventional protective layer thickness of 6 cm, even if the concrete strength grade reached C50, the service life remained relatively low. Additional anticorrosion measures, such as internal mixing and external coating, were required to improve the durability of the structure. Considering factors such as engineering costs and structural durability, the adoption of OAC structures for nearshore engineering is recommended. When the concrete strength grade is C50 or higher, the protective layer thickness is greater than 14 cm, and when the high-permeability epoxy protective material SP is applied externally, the service life of the underwater structure can reach up to 100 years. It is recommended that CAC structures be used in offshore engineering applications. When the concrete strength is greater than C65 and the thickness of the protective layer is 10 cm, the combined anti-corrosion measure of mixing MA and coating SP can significantly improve the service life of the engineering structure.

Single-crystal silicon carbide (SiC), as a wide-bandgap semiconductor material with excellent properties, is widely used in high-power electronic devices and optoelectronic fields. However, its high brittleness, extreme hardness, and strong chemical inertness pose significant challenges for achieving efficient and low-damage polishing. Chemical mechanical polishing (CMP) cannot meet industrial efficiency requirements owing to its slow reaction kinetics. Therefore, this study introduces ultrasonic vibration into the photocatalytic chemical mechanical polishing (PCMP) method to investigate the synergistic enhancement mechanism of ultrasonic-assisted photocatalysis and the material removal mechanism under multi-energy field interactions, with the aim of advancing the development of multi-energy field collaborative polishing technology. Three different experiments were designed to evaluate the effects of ultrasonic frequencies (0, 22, 25, 28, and 40 kHz) on the chemical and mechanical performance. This study combined photocatalytic oxidation with ultrasonic vibration, using nano-TiO₂ as a catalyst under UV irradiation to induce cavitation effects. The Oxidation performance characterization tests utilized a methyl orange solution as an indicator, with the decolorization time of the polishing solution under ultrasonic-assisted photocatalytic conditions used to assess oxidative strength being shorter, indicating a stronger oxidation capability. The static corrosion tests involved immersing the SiC samples in the polishing solution for 2 h under ultrasonic-assisted photocatalytic conditions. The resulting oxide layers were quantified using scanning electron microscopy and X-ray photoelectron spectroscopy. Ultrasonic-assisted PCMP experiments were conducted using SiO₂ abrasive slurry for 2 h, with the material removal rates and surface roughness measured to evaluate polishing performance. At 22 kHz ultrasonic vibration, the methyl orange decolorization time was 229 s, the oxygen content on the corroded surface reached 2.94at.%, the material removal rate was 503.47 nm / h, and the surface roughness was 48.28 nm. Compared with photocatalytic oxidation alone, ultrasonic assistance reduced the decolorization time by 117.90%, increased the oxygen content by 215.96%, improved the material removal rate by 52.63%, and reduced the surface roughness by 91.30%. The electron-hole pairs generated by the photocatalyst under illumination effectively promoted the formation of highly oxidative radicals (e.g.,·OH) in the reaction environment, accelerating the formation of oxide layers. The·OH in the polishing solution oxidized the surface, forming oxide layers primarily composed of Si and C oxides, which exhibited significantly lower hardness, strength, and bonding strength compared with the original SiC surface, thereby allowing easy removal using diamond or silica abrasives. Ultrasonic vibration enhanced both the chemical oxidation and mechanical removal stages of the polishing process. During ultrasonic propagation in liquids, cavitation bubbles formed and collapsed rapidly upon reaching a critical size during the compression cycles, generating localized high-energy microenvironments with temperatures exceeding 5 000 K and pressures up to 1 000 atm. Ultrasonic effects accelerated the mass transfer among the reactants, catalysts, and radicals, reduced the diffusion resistance, rapidly removed intermediate products generated during photocatalytic reactions, prevented reaction blockage, promoted electron-hole pair separation, reduced recombination rates, increased·OH concentration, and significantly improved the photocatalytic oxidation efficiency. The collapse of the cavitation bubbles enhanced the kinetic energy of the catalysts and abrasives, increasing the contact frequency and efficiency between the workpiece, catalysts, and abrasives, thereby improving the oxidation rate and mechanical removal efficiency of SiC. Ultrasonic vibrations also promoted the uniform distribution of photocatalysts and abrasives, eliminated catalyst agglomeration, increased the reactive surface area, enhanced the photocatalytic efficiency, and improved the surface uniformity and consistency. In addition, the localized high-temperature environments generated by cavitation bubbles further enhanced the chemical reactions. Notably, lower ultrasonic frequencies exhibited stronger cavitation effects, significantly improving the efficiency of ultrasonic-assisted PCMP. Owing to the synergistic effects of ultrasonic vibration, photocatalysis, and mechanical forces, the wear characteristics of the surface were significantly different from those after traditional grinding and polishing. Ultrasonic action improves the fracture toughness, facilitates plastic removal, and reduces subsurface damage. Therefore, integrating ultrasonic vibration into PCMP enhances the photocatalytic activity and abrasive kinetic energy, increases the oxidation rates and removal efficiency, and enables more efficient polishing of single-crystal SiC.

The accumulation of surface ice poses significant safety risks for operating engineering machinery, which can potentially lead to severe security incidents and economic losses. Presently, the pursuit of stable and effective anti-icing techniques for engineering applications is a significant scientific problem. Conventional anti-icing strategies, such as the utilization of chemical anti-icing agents, thermal anti-icing, and mechanical anti-icing, are characterized by low efficiency, high costs, and environmental unfriendliness. In response to these issues, researchers actively explored biological organisms with anti-icing properties in nature and proposed multiple strategies based on the principles of bionics, such as bio-inspired superhydrophobic anti-icing coatings, bio-inspired super-slippery anti-icing coatings, and bio-inspired antifreeze protein anti-icing coatings. Bio-inspired anti-icing coatings showed excellent anti-icing performance with low costs and low energy consumption, providing a foundation for the large-scale engineering application of anti-icing coatings. This review summarizes the latest research progress of bio-inspired anti-icing coatings for engineering applications, describing the anti-icing mechanisms and the preparation processes of anti-icing coatings, respectively. The three primary types of examined bionic coatings are superhydrophobic surfaces (SHS), slippery liquid-infused porous surfaces (SLIPS), and antifreeze protein (AFP) coatings. Superhydrophobic anti-icing coatings are inspired by the self-cleaning properties of the lotus leaf, which exhibits remarkable water-repellence because of its micro- and nanostructured surface. Superhydrophobic coatings effectively deter ice nucleation by minimizing water contact and reducing surface energy. However, it remains the challenges of improving their durability and resistance to environmental, particularly in industrial settings. Super-slippery anti-icing coatings modeled after the slippery surfaces of pitcher plants use a liquid lubricant trapped within a porous structure to create a non-stick surface. This design prevents ice from adhering to the coated surface, even under dynamic and fluctuating conditions. Super-slippery coatings demonstrate exceptional anti-icing performance; however, their dependence on specific lubricants raises concerns related to environmental compatibility and long-term maintenance. The antifreeze protein anti-icing coatings mimic the antifreeze proteins found in Antarctic fish, which inhibit ice crystal growth at the molecular level. Although antifreeze protein anti-icing coatings are promising in laboratory settings, their scalability and cost-efficiency for industrial applications remain areas requiring further exploration. This review encapsulates a variety of methodologies employed for evaluating the anti-icing efficacy of coatings, which are designed to replicate the stringent environmental conditions encountered in practical scenarios and for quantifying the resistance to ice formation and adhesion. Laboratory-based assessments, which include freeze-thaw cycle experiments, measurements of ice adhesion strength, and ice accretion delay tests, are delineated, thereby providing a comprehensive overview. Complementary to these, outdoor environmental experiments are discussed for contributing to validating the performance of the coatings under real-world circumstances. Further, this review addresses deficiencies inherent in the current assessment protocols and advocates for standardizing evaluation methods to guarantee the precise and consistent measurement of coating performance. This review provides an in-depth examination of the construction technology research pertaining to biomimetic anti-icing coatings and delineates the intricate process of preparing these coatings, encompassing the selection of raw materials, optimization of ingredient ratios, and coating methodologies. Further, this review presents a series of application tests that demonstrate the effectiveness of bionic anti-icing coatings in multiple sectors, such as aviation, construction, and transportation infrastructure. These tests affirm the high efficiency and reliability of the coatings in inhibiting ice formation, validating their utility in preventing hazards associated with icing in these critical domains. These studies advanced the process of bio-inspired anti-icing coating engineering applications and improved efficiency and stability in practice. Finally, based on the current research status, this review summarized the challenges and limitations of bio-inspired anti-icing coatings in the process of engineering applications, aiming to provide valuable references and insights for promoting the engineering applications of anti-icing coating.

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.

Diamond-like carbon (DLC) films are renowned for their exceptional wear resistance, low friction factor, and high hardness, which have led to their widespread application in the automotive, aerospace, and mechanical manufacturing industries. Various advanced techniques have been developed to control the properties of DLC films and prolong the service lives of mechanical components under wear and corrosion conditions, thereby enhancing their performance. The body of research in this field is continuously being enriched and refined. However, there is a scarcity of comprehensive review papers, which are crucial for guiding the development of the entire industry and academic domain. In response to this need, this study systematically summarizes the existing research on the wear-resistant properties of DLC films from both domestic and international perspectives, focusing on aspects such as preparation technology, process parameter optimization, modification through element doping, gradient construction, and surface texturing. A comprehensive aggregation of the research results strongly suggests that the meticulous adjustment of the process parameters is indispensable for marked enhancements in the hardness and wear resistance of DLC coatings. Element doping can improve the structure and properties of DLC films to achieve high elastic recovery as well as low friction and wear; gradient construction can strengthen the adhesion, hardness, and wear resistance of DLC films; and surface texturing can enhance the tribological performance of DLC films. Therefore, by finely controlling the process parameters, types and contents of doping elements, and design of surface structures, the microstructures of DLC films can be effectively altered to achieve an increase in the wear resistance, a reduction in the friction coefficient and wear rate, and enhanced adhesion, hardness, and wear resistance. These improvements are beneficial for extending the service lives of mechanical components under severe operating conditions. By comprehensively adjusting the manufacturing processes and other strategies for DLC films, this study achieves an overall upgrade in wear-resistant performance, thus filling the void in the industry for a systematic review on the optimization of DLC film properties. The research summarized in this study covers a range of deposition techniques, including physical vapor deposition (PVD), chemical vapor deposition (CVD), and plasma-enhanced chemical vapor deposition (PECVD), which are vital for achieving the desired film properties. The optimization of process parameters, such as the substrate temperature, deposition pressure, ion energy, and gas flow rates, is discussed, as all these parameters are critical for controlling the structure and performance of the film. The role of element doping in modifying the properties of films is investigated, with a focus on the use of transition metals, rare earth elements, and other alloying agents to enhance certain characteristics of DLC films. Furthermore, the study explores the concept of gradient construction, where the compositions and structures of films are varied throughout their thicknesses to create a gradient that can improve adhesion to the substrate and enhance mechanical properties. The study also addresses surface texturing, which involves the creation of micropatterns on the surface of a film to reduce friction and wear, which is a feature of particular importance for applications in which tribological performance is critical. In conclusion, this study provides a thorough overview of the research and development in DLC film technology by highlighting the key areas that are essential for the advancement of the field. This study underscores the importance of a holistic approach to the design and fabrication of DLC films and emphasizes the interplay among preparation techniques, process optimization, material modification, and surface engineering to achieve superior wear-resistant performance. This comprehensive review is significant in guiding future research and fostering innovation in the application of DLC films across various industries, and it serves as an essential reference for the further development of related technical fields.

Laser cladding is widely used in the repair of key components of aircraft engines due to its advantages, such as a small heat-affected zone, low dilution rate, good interface metallurgical bonding, and easy implementation of flexible processing. Stress changes induced by rapid heating and cooling during laser cladding and the complex composition of the cladding powder are important causes of cladding defects. Accurately detecting pores to actively regulate cladding porosity is important for improving the surface quality of cladding parts. To enhance the accuracy of porosity detection within laser cladding repair components and adjust the parameters of the laser cladding process, thereby reducing defects such as porosity and cracking in the cladding layer and improving the quality of the laser cladding layer, laser cladding experiments on IN718 nickel-based alloys with various process parameters were conducted in this study. In addition, an improved SP-YOLOv5 algorithm is developed for porosity detection. Initially, a Coordatt attention mechanism module is integrated between the input and convolutional layers to augment the spatial location information weight within the feature map. Subsequently, the YOLOv5 network structure was restructured to bolster its capability for detecting small targets of the porosity class. Furthermore, soft-NMS was implemented in place of the original Non-Maximum Suppression (NMS) for post-processing the detection results, which further reduced the false negative rate of the network. The porosity detection results yielded by the SP-YOLOv5 algorithm were compared with those of YOLOv5, Faster RCNN, RCNN, and ImageJ software analyses, revealing that the SP-YOLOv5 algorithm model achieved the highest accuracy improvement of 10.57%. Based on these findings, measurements of the laser cladding pool temperature, pool area, porosity rate, melting width, melting height, and melting depth of the cladding layer cross-section were performed. The results showed that the area of the molten pool was positively correlated with the laser power and powder feeding rate. As the laser power increased from 1 000 to 1 400 W, the average area of the molten pool increased from 5.77 to 10.52 mm². On the contrary, the melt-pool area was negatively correlated with the scanning speed. Similarly, the height, width, and depth of the molten pool were positively correlated with the laser power and powder feeding rate, and negatively correlated with the scanning speed. A regression prediction model correlating the laser cladding process parameters with the porosity rate was established using a stacking algorithm, and an optimal set of laser cladding process parameters was derived using a target optimization algorithm. Finally, laser cladding experiments were conducted using the optimal combination of process parameters (laser power of 1 330 W, scanning speed of 460 mm / min, and powder feeding rate of 13 g / min), and the porosity parameters were measured. The experimental results showed that under these optimized parameters, the consistency between the porosity predicted by the stacking model and the actual measured values reached 97.5%, verifying the effectiveness of the optimization method and significantly improving the quality of the cladding layer. The results of this study provide a theoretical foundation for the effective control of porosity defects in laser cladding layers and expand the application of machine vision in thermal repair processes.

As integrated circuit (IC) manufacturing technologies advance and feature sizes reduce to the nanoscale, the chemical mechanical polishing (CMP) process is imposed by increasingly stringent precision requirements. This is because slight variations in material removal can cause device failure. In particular, for metal CMP processes, achieving accurate real-time endpoint detection is essential for ensuring controllable material removal and maintaining high-quality process outcomes. Compared with other conventional endpoint detection methods based on frictional or optical principles, the eddy-current method has emerged as an optimal solution for detecting the copper film thickness variation during copper CMP process. As a non-destructive testing technique characterized by high sensitivity, rapid response, and high resistance to environmental interference, the eddy-current method provides a reliable approach for in-situ thickness measurements under complex polishing conditions. Focusing on the challenges in detecting nanoscale metal film thicknesses, a simulation model of the eddy-current sensor is established in this study by coupling an electromagnetic field and an electrical circuit. Based on the numerical simulations, the effects of fundamental parameters, including coil parameters (e.g., excitation frequency, wire diameter, inner radius, turns, and diameter-height ratio), and signal-conversion module parameters of the detection-circuit (e.g., parallel capacitance, voltage division resistance, and bridge arm resistance) on sensor performance are systematically revealed. Then the coil parameters are further optimized. And the optimal parameter values are determined specifically for CMP applications under a lift-off distance of 2 mm (corresponding to the typical thickness of a polishing pad). Subsequently, the detection circuit is optimized with emphasis on the signal-conversion module, including two fundamental circuit topologies, i.e., an LC resonant circuit and an AC bridge circuit, by determining their respective optimal values of key electrical parameters, meanwhile, the other modules, such as the signal-generation module and peak-detection module are well accomplished for a good measurement performance. Furthermore, the influences of environmental parameters, particularly lift-off distance and temperature, on the output characteristics of the detection coil is revealed. To quantify the influence of lift-off distance variations, a quantitative thickness-error assessment model is developed that correlates the film thickness, measurement error, and lift-off distance. Additionally, a decoupling calculation method is proposed by establishing a mathematical relationship correlating the output voltage, film thickness, and temperature, thereby diminishing the influence of temperature variations on the thickness measurement. Finally, a nanoscale metal film thickness eddy-current detection system is developed. The system comprises an eddy-current sensor, precision displacement modules, and a vacuum-based wafer-holding module featuring a microporous ceramic vacuum chuck. The probe is mounted on a non-metallic cantilever beam fixed to the linear-displacement module to minimize lift-off distance variations, whereas the vacuum chuck ensures stable wafer holding on the rotary-displacement module. The coordinated motion of the linear- and rotary-displacement modules enables precise thickness measurements at multiple locations on the wafer surface. According to the experimental testing at a lift-off distance of 2 mm, the self-developed detection system demonstrates a sensitivity of 1.38 mV/nm and a linearity coefficient of 0.986 9 within a measurement range of approximately 1.5 μm. And a comprehensive evaluation of the measurement performance, based on the output-voltage fluctuation and sensitivity, shows that the detection system can achieve a nanoscale precision measurement of copper film thickness over a wide range. This study facilitates advancements in high-precision in-situ detection technology for high-quality polishing processes.

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.