Cf/SiC复合材料与Nb连接冶金机制及界面反应调控与机理

The application of the composites in the thrust chamber will be more widely in the future. However, the joining quality is not stable and the mechanism is unclear when joining Cf/SiC composites to Nb metals, which limits the development of the novel engines. Based on the requirement of the joining between large-scaled Cf/SiC composited nozzles and Nb transition ring in thrust chamber of the attitude control engine, the fundamental issues between joining of Cf/SiC to Nb are investigated to clarify the metallurgical mechanism and optimize the interfacial reaction. This project focuses on the reaction mechanism of the joint. The novel heat-resistant high-temperature filler metals will be optimized. The composited filler metal and welding structure are designed according to the calculation results of the residual stresses. The evolution of the interfacial microstructure of the joint is studied. The relationship between interfacial reaction products and joint properties is disclosed. The joining mechanism and effective optimization of the reaction products in the joint is investigated. The aim of the project is to produce large-scale Cf/SiC composited nozzles and Nb composited components and establish the standard of the testing for the components. Therefore, the results in this project will offer the theoretical and technical support for the development of the novel space engines.

复合材料在推力室制造中的应用将越来越广泛,然而现有Cf/SiC复合材料与金属Nb连接技术的质量不稳定且连接机理不明确，已成为限制新型号发动机开发的瓶颈技术。本项目针对姿控发动机推力室大尺寸Cf/SiC复合材料喷管与Nb过渡环连接需求，以全面揭示接头冶金机理和实现界面反应产物调控为基本出发点，系统研究Cf/SiC复合材料与Nb连接的基础问题。本项目重点研究接头的界面反应机理，优化设计新型耐高温钎料体系，基于接头的应力分析优化设计复合钎料体系和焊接结构，阐明接头的界面组织演化规律，揭示界面反应产物与连接性能的对应关系，阐明接头的连接机理，实现界面反应产物的有效调控，最终实现大尺寸Cf/SiC复合材料喷管与Nb金属连接构件的制备，制定复合材料喷管产品的检测标准，为新型号航天发动机的研制提供核心的基础理论和关键技术支持。

本项目针对姿控发动机推力室大尺寸Cf/SiC复合材料喷管与Nb连接瓶颈技术，以全面揭示接头冶金机理和实现界面反应产物调控为基本出发点，系统研究了Cf/SiC复合材料与Nb连接的基础问题。设计了TiNiNb，TiCoNb和TiZrNiCu+Ti箔等高温钎料、碳纳米管作为增强相的复合钎料，研究了高温钎料与复合钎料的力学性能与高温性能，实现了新型耐高温钎料体系的优化设计。阐明了钎料在复合材料表面的润湿机理，揭示了不同种钎料与母材的反应机理，表征了钎料与母材间的反应产物，阐明了工艺参数对接头组织与性能的影响，解明了接头的连接机理。根据实际试样结构建立了有限元模型，分析了接头中残余应力的分布，并揭示了剪切试验下接头中的应力分布规律，阐明了接头组织与接头钉扎结构对接头力学性能的影响。构建了CNTs/TiNi复合钎料体系，研究了CNTs增强相含量对复合钎料强度，热膨胀系数与对母材润湿性的影响规律，阐明了复合钎料中各组元间及钎料与母材的反应机制，揭示了复合钎料提升接头力学性能的机理。阐明了工艺参数对接头组织与性能的影响规律，优化接头性能，揭示了接头的破坏形式与断裂机理，建立了连接参数与接头组织和力学性能的联系，实现界面反应产物的有效调控。Cf/SiC复合材料与金属连接接头室温抗剪强度达到了192MPa，800℃和1000℃高温抗剪强度分别达到202MPa和124MPa，远超项目研究目标要求的接头室温抗剪强度大于140MPa，800℃高温抗剪强度大于100MPa，接头焊合率达到了98%，也远高于项目研究目标要求的95%，并且达到0.6~0.8MPa下接头不泄露，最终实现大尺寸Cf/SiC复合材料喷管与Nb金属连接构件的制备，为新型号航天发动机的研制提供核心的基础理论和关键技术支持。研究工作得到国内外同行的广泛关注，多次受邀在国内外学术会议上做特邀报告。发表学术论文39篇，其中SCI论文32篇，EI论文6篇，出版学术专著2部，申请国家发明专利21项，已获授权11项。荣获国家科学技术奖自然奖二等奖1项，黑龙江省科学技术奖自然奖一等奖1项（公示中）。