贝壳仿生Yb-Si-X/Mo-Si-X硅基复合涂层界面调控及抗氧化机理

针对硅基复合涂层在热氧水汽环境下脆性大、易热应力开裂、界面组织结构高温不稳定的难题，本项目提出一种在Nb合金表面构建贝壳仿生硅基复合涂层的新思路，即利用等离子喷涂技术制备Yb-Si-X/Mo-Si-X(X=Al,Hf,O)仿生涂层，借助仿生结构中基/夹层交替分布和夹层高温粘性流变特性，提升涂层体系的断裂韧性，同时利用Al2O3-SiOC/HfO2夹层的扩散屏障特性，阻挡高温下层间界面组元之间的元素互扩散，结合Yb2SiO5抑制水汽对自生保护膜的侵蚀，提升硅基涂层在热氧水汽环境下的组织结构稳定性。系统研究单源前驱体合成和填料改性聚合物转化陶瓷制备硅基复合粉末的微观结构，探讨等离子喷涂制备仿生涂层的组织结构、孔隙分布与层间界面结合状态，确立热氧水汽环境下涂层组织结构演变与抗氧化性能之间的关联，揭示贝壳仿生涂层的抗氧化机理，为将其应用于空天飞行器热端部件的防氧化提供理论支撑。

To solve the problems of brittleness, thermal-stress-derived cracking, and high temperature instability of the interface structure of silicon-based composite coatings in hot-oxygen water-vapor corrosive environment, this project proposes a new idea of constructing shell bionic silicon-based composite coatings on Nb alloys. The proposed biomimetic coating is the Mo-Si-X/Yb-Si-X (X=Al, Hf, O) composite coating which will be prepared by plasma spraying technology. The fracture toughness of the coating will be improved by alternating the distribution of the base/interlayers in the biomimetic structure and the high-temperature viscous rheological properties of the interlayer. Meanwhile taking advantage of the diffusion barrier characteristics of the Al2O3-SiOC/HfO2 interlayer, the coating will prevent the inter-diffusion of elements between the layers at high temperatures. Besides, Yb2SiO5 will be incorporated to inhibit the water vapor erosion on the self-generated protective film of the biomimetic coating, as well as to improve the stability of the interface structure of the coating in the hot-oxygen water-vapor corrosive environment. Systematic research on the microstructure of single-source precursor synthesis and filler-modified polymer-derived ceramics to prepare silicon-based composite powder will be developed. The microstructure, pore distribution, and interface bonding of the biomimetic coating prepared by plasma spraying will be studied. The relationship between the microstructure evolution and the oxidation resistance of the coating in the hot-oxygen water-vapor corrosive environment will be established. Finally, the oxidation resistance mechanism of the shell bionic coating will be proposed, which furthermore will provide theoretical support for the coating applied on the hot end parts of aerospace aircraft engines in the future.