难熔金属表面TaC扩散障的高温退化机制及其对硅化物涂层抗高温氧化性能的影响机理研究

硅化物涂层作为难熔金属最主要的高温抗氧化涂层，与难熔金属基体的化学成分存在显著差异，服役过程中涂层/基体界面不可避免发生高温互扩散，导致涂层寿命缩短以及基体力学性能下降。本项目拟在难熔金属/硅化物涂层界面制备TaC陶瓷扩散障，通过开展难熔金属表面TaC高温扩散障的界面结构反应形成机制、阻扩散性能与高温退化机理研究，阐明真空熔烧过程中TaC扩散障与硅化物料浆预置层界面反应对TaC扩散障成分和结构的影响机理，确定硅化物涂层/TaC扩散障的界面结构；明确TaC扩散障对硅化物涂层/难熔金属基体界面互扩散行为的影响机制；揭示长时服役过程中TaC扩散障的高温退化机理及其对硅化物涂层高温防护性能的影响机制，提出难熔金属表面长寿命硅化物涂层的金属/陶瓷、陶瓷/陶瓷界面自适应匹配和相容性设计理论与方法，为可重复使用火箭发动机以及高性能姿轨控火箭发动机难熔金属热端部件长寿命高温防护涂层的设计提供理论依据。

Because of the various chemical compositions between silicide coatings and refractory alloys, interdiffusion and interfacial reactions occur inevitably at their interfaces during service at high temperatures. This leads to a shortened service life for the silicide coating and a reduced mechanical strength for the refractory alloy substrate. Aiming at restraining the interdiffusion between the silicide coatings and refractory alloys, a layer of TaC diffusion barrier is prepared at the silicide coating/refractory alloy substrate interface. In this project, the interfacial reactions between silicide slurries and the TaC diffusion barrier during high temperature sintering process as well as their effects on the composition and microstructure of TaC diffusion barrier will be studied. Furthermore, the effects of TaC diffusion barrier on the interdiffusion behaviors between silicide coatings and the refractory alloys in addition to the degradation mechanisms of TaC diffusion barrier will be systematically investigated. Moreover, the effect of TaC diffusion barrier on the high temperature oxidation resistance of silicide coatings will be investigated as well. Based on these studies, the methods of stabilizing the coating/alloy interfacial structure can be acquired, which will be beneficial to establish the theoretical foundation for the design and application of long service life coatings on refractory alloy components of reusable rocket engines and high performance of orbit and attitude control rocket engines.