高温结构材料，如碳/碳化硅（C/SiC）复合材料、镍基高温合金等，被广泛应用于航天航空、燃气轮机等领域。高温结构材料的服役环境涉及力-化学、流-固-热等多场耦合问题，材料的抗氧化烧蚀性能及稳定的高温力学性能，对材料和结构的稳定性、安全性至关重要。本文针对C/SiC复合材料的抗氧化烧蚀机理、抗氧化烧蚀性能提高和高温合金材料的力-化学耦合机理，开展了如下研究工作：首先，本文发展了一套简单、易操作的高温在线测量系统，该系统能够方便地集成在氧乙炔烧蚀等高温实验平台，结合高温滤波、高温图像处理方法，可实现对材料表面变形特征、流动演化过程的在线捕捉和定量表征，提供传统实验研究中所缺失的材料在线演化信息。其次，本文通过添加高熔点物质（ZrO2和ZrB2）来研究提高C/SiC复合材料抗氧化烧蚀性能的方法，通过氧乙炔烧蚀实验对比了C/SiC，C/SiC-ZrO2和C/SiC-ZrB2材料在干燥和湿热环境下的氧化烧蚀性能。结合扫描电子显微镜对试件烧蚀前后表面形貌的观察分析，分析了材料表面由于烧蚀造成的三种微结构（气孔、裂纹、烧蚀坑内的骨架结构）的形成机制。然后，基于本文发展的在线测量方法，研究了碳化硅（SiC）材料在氧乙炔火焰烧蚀过程中表面液态二氧化硅的生成、流动和融合过程；并基于表面流动演化的机理研究，从仿生学的角度出发，对SiC材料表面进行微结构设计，获得了一种基于表面微结构改性来提高材料抗氧化烧蚀性能的方法。再次，本文从宏观尺度的高温三点弯曲实验和微观尺度的高温纳米压痕实验两方面，研究了高温合金材料在外加应力条件下的力-化学耦合机理，验证了外加拉应力促进氧化，压应力减缓氧化的结论。此外，本文从实验和理论上研究了穿晶裂纹和沿晶裂纹尖端氧化物的生长演化过程，并利用Eshelby夹杂理论，结合应力-扩散氧化耦合理论，分析对比了不同外加应力条件下沿晶裂纹尖端氧化物的生长和侵入深度，揭示了力-化学耦合效应和材料微结构相互作用的机制。最后，本文利用高温纳米压痕实验研究了微纳米尺度下氧化过程和微结构表面形貌的相互作用。从实验和理论两方面，解释了纳米尺度下表面局部曲率影响局部氧化速率、氧化反过来改变表面形貌演化的作用机制。

High temperature structural materials, such as C/SiC composites, Ni-based superalloys, have wide applications in aerospace industry and gas turbines,etc. The service conditions of high temperature structural materials involve chemo-mechanical, fluid-solid-thermal coupling process. Excellent oxidation and ablation resistance and stable mechanical properties of such high temperature structural materials in high temperature environments play a critical role in determining the stability and safety of the materials as well as the structural components. In order to understand the thermal oxidation and ablation mechanisms and to improve the thermal oxidation and ablation resistance of C/SiC composites as well as to investigate the chemo-mechanical coupling mechanisms of high temperature superalloys, this paper therefore focuses on the following research topics:First, a simple system for real time observation at high temperature is developed and this system can be conveniently integrated to the setup of ablation test. Together with the high temperature filtering technique and image processing method, we are able to obtain the surface ablation process as well as its evolution during high temperature experiments. Thus, it provides information for the real time deformation and surface evolution of materials under experimental conditions and helps to better understand the failure mechanisms. Second, we study how to improve the oxidation and ablation resistance of C/SiC composites by adding high temperature additives (ZrO2 and ZrB2). Thermal ablation tests by using oxyacetylene torch flame are carried out to compare the thermal ablation resistance of C/SiC，C/SiC-ZrO2 and C/SiC-ZrB2 in air and with water vapor, respectively. With the aid of scanning electron microscope, the formation mechanisms for three typical surface microstructures, i.e., bubbles, surface cracks, and bone structures in the ablation pit are proposed to better understand the surface degradation in thermal oxidation and ablation condition.Then, the surface evolution of SiC material subjected to thermal ablation is studied by adopting the real time observation technique developed in this paper. The generation, coalescence and floating process of liquid SiO2 on the surface of the specimen are clearly captured and the underlying mechanisms for such fluid-solid-thermal coupling process is studied. Furthermore, based on the mechanisms revealed for the surface flowing of liquid SiO2 as well as the concept of biomimetic, microstructures are designed and fabricated on the surface of specimens by using laser beam machining. Simulations and experiments are conducted to confirm that such microstructures on the surface of the specimens are able to modify the surface flow fields and improve the oxidation and ablation resistance by locking in the liquid SiO2 in the microstructures. Moreover, the coupling effect between externally applied load and diffusion controlled oxidation for high temperature superalloys is studied both at macroscopic scale by using high temperature three-point bending test and at microscopic scale by using high temperature nanoindentation test, respectively. Results show consistenly that externally applied tensile stress increases oxidation rate, while compressive stress decreases it. Besides, this paper also investigates the oxide formation and revolution at the tip of intragranular crack and intergranular crack. By using Eshelby’s inclusion theory and combining the chemo-mechanical coupling effect, analysis is carried out to compare the oxide intrusion depths at the crack tip under different stress levels. The mechanisms for the interaction of chemo-mechanical coupling effect and the microstructures of materials are revealed.Finally, this paper investigates the interaction between oxidation and surface morphology and curvature of microstructures at small scales. It is experiementally and theoretically demonstrated that surface curvature can affect the oxidation rate locally, while oxidation in turn can change the surface morphology at small scales, particularly at nano scale.