高温环境下热防护材料氧化烧蚀在线测试技术与失效机理研究

The study of heat protection material oxidation and ablation process real time observation technique is crucial to reveal the failure mechanism of the material in high temperature environment. The research project is aimed at designing a deformation measurement optical mechanical system based on digital image local invariant feature extraction. Digital images colorimetric method and hyperspectral imaging technique are obtained to measure the full field temperature distribution and oxidation rate synchronously. The real time full field surface deformation, temperature distribution and oxidation rate of the heat protection material specimen in the process of oxidation and ablation can be realized by the designed measurement system. Then the coupling effect between surface stress and surface oxidation is studied to establish theoretical model of surface stress and oxidation rate relation. Then the specimen surface stress can be obtained by the theoretical model from the specimen surface deformation, temperature distribution and oxidation rate. The theoretical model validity is tested by comparison with the experimental results. Moreover, the heat protection material surface microstructure designment aided by computer simulate computation is obtained to control the surface stress in oxidation and ablation process based on the coupling effect mechanism between surface stress and surface oxidation. Then the surface microstructure optimization designment is obtained to improve the ablation resistance of heat protection material.

高温环境下热防护材料氧化烧蚀演化过程在线实时监测对热防护材料失效机制研究至关重要，本研究项目计划发展一套基于图像局部不变特征提取变形测量光测力学测量系统，结合比色法和高光谱成像技术，同时获取被测试件表面的温度分布和氧化速率，实现热防护材料氧化烧蚀演化过程表面形貌、温度和氧化速率的在线、实时、全场测量。基于力学-化学耦合作用机理，建立应力同热防护材料氧化烧蚀速率的理论模型，通过氧化烧蚀过程中材料表面变形、温度变化和氧化速率对材料应力进行分析，同实验结果对比验证理论模型有效性。基于热防护材料氧化烧蚀力化学耦合机制和数值计算手段，通过热防护材料表面微结构设计，调控氧化烧蚀过程中应力分布，来提升热防护材料的热防护性能。

热防护材料性能是制约飞行器等航天航空领域设备服役于高温环境下耐久性的关键因素，热防护材料高温环境下氧化烧蚀在线测试技术及其失效机理研究是评价热防护材料使用性能、验证气动热模型和算法、指导热防护设计的必要手段。由于热防护材料服役环境测试温度可达2000℃以上，传统测试方法对其烧蚀过程缺乏过程分析，无法对材料在高温工况环境中演化过程进行准确跟踪。本项目首先针对高温环境下热防护材料烧蚀过程特点，发展了一套热防护材料高温环境下氧化烧蚀演化过程在线检测方法和技术，对高温光学测试中环境干扰进行分析，提出了去除空气扰动和辐射光影响方法，结合图像处理方法提出光学测量方法提取高温环境下获取图像中的局部特征，捕捉热防护氧化烧蚀中的温度和变形信息。结合热防护材料高温环境下氧化烧蚀演化力化学耦合作用机制研究，考虑热防护材料氧化膜生长加厚过程中氧化的双向扩散机制，建立了氧化膜生长同时具有氧分子向材料基体扩散向内氧化和基体粒子向氧化膜扩散带来的向外氧化的力化学耦合物理模型。利用数值模拟对比试验测试结果，分析了表面微结构对热防护材料烧蚀的影响，建立了氧乙炔火焰烧蚀热防护材料C/SiC表面模型，为提高和优化C/SiC材料的烧蚀性能提供了解决方案。