高温吸波/结构型陶瓷基复合材料的协同设计/制备基础

SiC fiber reinforced SiC matrix composites (SiC/SiC) has excellent high-temperature mechanical properties, though it exhibits high dielectric constant and low dielectric loss,leading to the low electromegnetic (EM) absorbing properties. If SiC matrix is replaced by Si-B-C-N matrix which has low dielectric constant and high dielectric loss, the as-received SiC fiber reinforced Si-B-C-N matrix composites (SiC/Si-B-C-N) may have both excellent mechanical properties and EM absorbing properties.Focusing on the urgent needs of jet engine on ceramic matrix composites, we propose to form Si-B-C-N matrix in SiC fiber preform, which is based on chemical vapor infiltration process (CVI). The research contents include:the relationship between phase composition/crystal structure of components and dielectric/mechanical properties of SiC/Si-B-C-N composites, EM asorbing mechanisms and integrated design/fabrication mechanisms, evolutions of the dielectric/mechanical properties in oxidizing environments at high temperatures. We will fistly design and fabricate SiC/Si-B-C-N composites with high dielectric loss based on impendence-matching optimization method, clarifying the mictrostructure controlling and the EM absorbing mechanisms and revealling the evolution principle of properties of the composites in oxidizing environments at high temperatures. The researches will lay a foundation for design, fabrication and application of high-temperature EM absorbing/structural integrated ceramic matrix composites.

SiC纤维增韧SiC复合材料（SiC/SiC）具有优异的高温力学性能，但介电常数高、损耗低，导致其对电磁波的吸收效能不足。采用低介电常数、高损耗Si-B-C-N系陶瓷基体替代SiC基体，制备SiC纤维增韧Si-B-C-N复合材料（SiC/Si-B-C-N），有望使其兼具优良的高温力学性能和吸波性能。本项目针对航空发动机对高温吸波结构型陶瓷基复合材料的迫切需求，采用化学气相渗透（CVI）法在SiC纤维预制体内形成Si-B-C-N系基体，研究SiC/Si-B-C-N复合材料的组分/微结构与介电/力学性能的关系、吸波机理与协同设计/制备基础、力学/介电性能在高温氧化环境中的演变等。本项目基于阻抗匹配优化，首次设计和制备高介电损耗SiC/Si-B-C-N复合材料，可望阐明其微结构控制机制和吸波机理，揭示其在氧化环境的性能演变规律，为自主发展高温吸波/结构型陶瓷基复合材料的设计、制备与应用奠定基础。

本项目针对航空发动机对高温吸波结构型陶瓷基复合材料的迫切需求，基于阻抗匹配优化，采用化学气相渗透（CVI）法，设计并制备了高介电损耗SiC/Si-B-C-N复合材料，并阐明其微结构控制机制和吸波机理、揭示其在氧化环境的性能演变规律，为发展高推动比航空发动机用吸波/热结构陶瓷基复合材料提供理论依据和技术支撑，对高超声速航天器发展也有指导意义。本项目共获授权国家发明专利7项，在国内外核心期刊和重要国际会议发表高水平论文70篇，总影响因子超过300。