碳/碳复合材料包埋固渗硅基陶瓷涂层扩散反应行为及复杂耦合环境下氧化损伤机理

In order to reduce the mechanical damage of carbon/carbon (C/C) during the preparation of Silicon-based ceramic coating, the diffusion and reaction behavior of the ceramic coating prepared by pack cementation with different technological parameter was investigated, and the multilayer coating with the transition layer was prepared. Silicon-based ceramic coating with good mechanical and oxidation resistant properties could be prepared by pack cementation, C/C composites with this coating would be serve as the thermal-structural parts of aero-engine. The relationship between the preparation process conditions of pack cementation, the structure of C/C matrix, the shape feature of the thin-walled complex component and the microstructure, element distribution, inner-stress, mechanical and oxidation resistant properties of the as-prepared coating were investigated. The diffusion and reaction mechanism of the coating prepared by pack cementations and the formation mechanism of the coating can be obtained. The effect mechnism of the transition layer prepared by different methods on the diffusion and reaction behavior and the microstructure and properties of the coating can be obtained. The inner-stress and homogeneity of the coating on the surface of thin-walled complex component can be established. The oxidation and damage mechanism, the change law of the microstructure and properties of C/C composites with the oxidation resistance coating under the complex coupled environment can be obtained. The above research can lay a theoretical foundation for the application of this kind of the ceramic coating prepared by pack cementation under high temperature, high speed air flow erosion environment.

本项目针对包埋固渗工艺在碳/碳(C/C)复合材料表面制备硅基陶瓷涂层对C/C复合材料力学性能损伤的难题，提出通过不同条件下包埋固渗涂层扩散反应行为的探索及采用过渡层构建多层复合涂层的方法，旨在制备出兼具良好力学性能及抗氧化性能的包埋固渗硅基陶瓷涂层，以满足航空发动机薄壁复杂热结构部件对C/C复合材料综合性能的要求。着重研究包埋固渗工艺参数、C/C基体结构、薄壁复杂构件外形特性等与所制备涂层微观结构、成分分布、内应力及力学和抗氧化性能之间的关系规律，阐明包埋固渗涂层扩散反应机制和涂层形成机理，揭示不同工艺制备的过渡层对涂层扩散反应行为及微观结构性能的作用机制，确立薄壁复杂构件表面涂层内应力及均匀性分布规律，揭示带有涂层的C/C复合材料在发动机模拟复杂耦合环境下的结构性能演变规律及氧化损伤机理，为实现包埋固渗涂层在高推比航空发动机高速气流冲刷环境下的应用奠定理论基础。

本项目针对包埋固渗工艺在C/C复合材料表面制备硅基陶瓷涂层对其力学性能损伤的难题，提出通过不同条件下包埋固渗涂层扩散反应行为的探索及采用过渡层构建多层复合涂层的方法，旨在制备出兼具良好力学性能及抗氧化性能的包埋固渗硅基陶瓷涂层，以满足航空发动机薄壁复杂热结构部件对C/C复合材料综合性能的要求。完成了(1)包埋固渗工艺参数对涂层扩散反应行为的影响规律及扩散反应机制探索；(2)C/C复合材料结构对包埋固渗过程中扩散反应行为的影响；(3)薄壁异形复杂构件表面涂层的微观结构及性能分布规律；(4)引入过渡层构建“过渡层/包埋外涂层”复合涂层及其微观结构性能研究；(5)复杂耦合服役环境下带涂层C/C的结构性能演变规律及损伤机理等方面的研究内容。获得了包埋固渗工艺参数、C/C结构、薄壁复杂构件外形特性等对所制备涂层扩散反应行为、微观结构和性能的影响规律。通过引入过渡层，有效缓解了包埋固渗过程中熔融硅对C/C基体的硅化侵蚀，提高了涂层C/C的力学性能；并通过工艺改进改进增加了复合涂层中具有优异抗氧化性能的组元，使复合涂层分别在1500℃和1700℃空气环境中有效防护时间超过500h和200h。阐明了过渡层对复合涂层的作用机制及不同条件下包埋固渗扩散反应机制。揭示了带涂层C/C在高温、加载及水氧复杂耦合环境下的氧化损伤机理。该项目的研究结果可为实现包埋固渗涂层在高推比航空发动机高速气流冲刷环境下的应用奠定理论基础。.本项目理论研究结果，发表SCI论文28篇，申请发明专利10项，授权4项，培养研究生5名。以部分研究结果为重要支撑，项目负责人获得2020年教育部自然科学一等奖和陕西青年科技奖。