TiAlSiN涂层力学性能改善措施的研究现状及进展

TiAlSiN涂层具有耐温性好、化学惰性高等优异性能，其作为防护层被广泛应用于摩擦零部件、机械加工工具上。但TiAlSiN涂层内应力过大导致的力学性能不足，限制了其在严苛工况下的进一步应用。总结了目前改善TiAlSiN涂层力学性能的主要措施：涂层微观结构优化、膜层结构设计以及热处理工艺。对改善涂层力学性能所涉及的细晶强化、共格效应、固溶强化以及模量差理论等机理进行了全面的描述，并详细地对比分析了上述理论之间的内在联系与差异。系统地讨论了纳米多层和梯度复合膜层结构对涂层力学性能的影响规律，主要从调制结构以及成分调整2个角度对膜层结构变化进行了分析，有利于指导具有良好力学性能的膜层结构的设计。此外，分别阐述了退火温度、时间以及气氛环境对TiAlSiN涂层力学性能的影响规律，分析了退火条件对涂层微观结构的影响以及微观结构与力学性能之间的关系。在此基础上，提出了未来可以从基础理论和改善措施之间的协同作用角度，对TiAlSiN涂层力学性能的改善展开进一步研究。

Research Status and Progress of Improving Mechanical Properties of TiAlSiN Coatings

TiAlSiN coatings have excellent high temperature resistance and chemical inertness, and they have been widely used on friction work pieces and cutting tools. However, their high internal stress limits their further application in industries under harshworking conditions. This paper focuses on the main techniques employed to improve the mechanical properties of TiAlSiN coatings, including microstructure optimization, micro-structure design and treatment. The coating hardness is predominantly influenced by microstructure, which can be tailored through various processing methods such as deposition method optimization, and modulation of the deposition process parameters including nitrogen flow rate, substrate bias, target quantity, and power duration. In addition, doping new elements and changing the original element content of TiAlSiN coatings also affect the hardness of the coatings. In this work, the mechanisms involved in improving the mechanical properties of the coatings, such as fine grain strengthening, solid solution strengthening and modulus difference theory, were compared and analyzed. The refinement of grain size resulting from fine-crystal strengthening reduced the crack propagation, while solid-solution strengthening was achieved by introducing foreign atoms into a compound to form a solid solution, thereby increasing the hardness of the TiAlSiN coatings. The coherent effect and modulus difference theory promoted the enhancement of TiAlSiN coating hardness through interface structure optimization. Both mechanisms induced interfacial stresses that prevented dislocation generation. The internal relations and differences between the above theories were compared and analyzed in detail. The effect of nano-multilayer and gradient composite layers on the mechanical properties of the coatings was systematically discussed. Modulation structure and composition adjustment were the two main factors that affected the variation of micro-structure. Currently, research on the strengthening mechanisms of nano-layered coatings and gradient-structured coatings is not comprehensive. Even small structural alterations to these coatings can cause various influence mechanisms that alter their mechanical properties. For instance, changing the modulation period significantly impacts the mechanical behavior of TiAlSiN coatings by means of coherent strain and the modulus difference theory. It is helpful to guide the design of membrane structure with good mechanical properties. In addition, heat treatment has the most significant effect on the properties of TiAlSiN coatings. So the influence of annealing temperature, annealing time, and atmosphere on the mechanical properties of TiAlSiN coatings was summarized. The effect of annealing conditions on the microstructure of the coatings and the relationship between the microstructure and mechanical properties were analyzed. In addition to experimental research, basic theoretical research was also be conducted by starting from first principles to identify the specific relationships and influence mechanisms between microstructure and mechanical properties of coatings. Annealing had three main effects on the mechanical properties of TiAlSiN coatings:grain coarsening, phase transformation, and surface oxide formation. Annealing resulted in grain coarsening, which improved the toughness of the coatings. The mechanical properties of TiAlSiN coatings were affected by the phase structure when phase transitions occurred during annealing. Additionally, the significance of the synergistic effect of improving measures on the mechanical properties of TiAlSiN coatings was emphasized. Finally, it was suggested to conduct deep research in future on improving mechanical properties of TiAlSiN coatings from basic theory and cooperation effect of various improvement actions.