极端高温环境三维能量耗散复合结构陶瓷设计与实现方法

The extreme high temperature environment thermal protection ceramics are one of urgent needs for aerospace craft. Constrained by the fiber, the upgrading of composite materials faces serious technical bottlenecks. The novel thermal protection monolith ceramics are ideal alternative plan. However, due to the brittle fracture, monolith ceramics aren’t mainstream applications. Although nacre-like ceramics and fiber monolith ceramics exhibited some ductile fracture characteristics, they still can’t meet the requirement of extreme high temperature environment. This project targets advanced Si-B-C-N based materials, and will (1) propose novel three dimensional energy dissipation composite ceramic structure with controllable crack deflection, bifurcation and propagation to substantial increase the fracture energy; (2) develop new mesostructure implementation method by CAD aided laser etching combined with gel casting method to realize multiscale composite structure; (3) to reveal failure mechanism in extreme environment for proposed composite structure, and realize online failure behavior observation by high temperature in situ loading CT technology. This project expects to gain original achievement in novel ceramic composite structure design, preparation and failure mechanism in extreme environment, and to develop new heat protection ceramics with bearing integration, which will provide theoretical and material technology support for the development of aerospace space thermal protection.

高端航天装备对极端高温环境防热陶瓷材料需求迫切。连续纤维复合材料升级换代受纤维制约，技术瓶颈突出，陶瓷防热材料是理想替代方案，但由于脆性断裂问题，目前难以获得主流应用。贝壳仿生和纤维独石结构虽表现出了一定的韧性断裂特征，但仍无法满足极端高温环境苛刻要求。项目针对极端高温环境特点，以Si-B-C-N纯陶瓷材料为对象，（1）拟提出裂纹可控扩展的三维多级能量耗散复合陶瓷结构设计新思路，大幅提高材料断裂能；（2）拟发展CAD辅助激光刻蚀精细结构实现新方法，结合凝胶注成型，实现三维复合结构多尺度组装；（3）揭示极端高温环境新型结构失效机理，并利用高温原位加载CT技术，实现新型结构破坏规律在线观测。项目期望在极端高温环境复合结构设计、制备和失效机理方面获得原创性成果，通过三维多级能量耗散复合结构设计新思路解决陶瓷材料极端高温环境脆性断裂难题，为高端航天装备热防护技术发展提供理论指导和材料技术支撑。

高超声速航天装备对耐烧蚀、高可靠陶瓷防热材料需求迫切。 高超声速飞行带来严酷的气动热力环境， 端头、翼前缘等部位温度达到 2000℃以上，热防护材料既要耐烧蚀、 抗氧化，又须抗热冲击和结构可靠，属于典型的结构功能一体化材料，纯陶瓷材料应用于极端高温环境，急需解决脆性断裂基础难题。 针对项目研究目标,项目凝练了三个亟待解决的基础科学问题： 1 极端高温环境三维能量耗散复合陶瓷结构设计方法； 2 精细细观结构实现机制与多尺度组装方法； 3 极端高温环境新型复合结构陶瓷失效行为与机理。最终解决了立项提出了三个基础科学问题，创新发展了极端环境高可靠陶瓷材料结构设计方法，将全陶瓷结构断裂韧性提高到13MPa.m1/2以上，为极端环境耐高温材料开发提供了基础方法和技术手段支撑，在航空航天热防护技术领域具有良好的应用前景。