超高温陶瓷在高超声速飞行器和再入大气层航天器上作为抗超高温氧化的结构材料有突出的应用前景，而其中ZrB2-SiC体系由于具有优良的烧结、高温力学、热力学稳定性而成为最有希望的候选材料。项目提出利用自建的可控气氛超高温氧化装置，研究在1600-2200℃温域不同气体流速和压力（氧分压）下ZrB2-20vol.%SiC的氧化行为，模拟计算不同空气流速和压力（氧分压）下试样表面的氧分压变化，系统了解主要环境因素对ZrB2-20vol.%SiC在超高温下抗氧化性的影响规律，深入认识气体流速和压力（氧分压）影响材料表面氧分压以及熔融和气相产物相向环境中逃逸，进而影响材料的氧化层生长和微观结构、氧化控制步骤以及活性氧化的机制。项目研究对于深入了解超高温陶瓷的氧化机制具有理论意义，同时对长寿命、抗氧化超高温陶瓷和高性能防护涂层体系的发展以及非烧蚀型防热材料的一体化设计具有实用价值。

Ultra-high temperature ceramics (UHTC) have a great application prospect as oxidaion resistant structural materials of hypersonic aerocrafts and reentry vehicles. Among these UHTC, ZrB2-SiC becomes a most potential candidate due to its easy sintering, good high temperature mechanical properties and thermodynamic stability. In this project, by utilizing environmental atmosphere controllable ultra-high temperature oxidation tester established by us, the oxidation behaviors of ZrB2-20vol.%SiC will be investigated at 1600-2200℃ in air with different flow rates and total pressures (oxygen partial pressures), the real oxygen partial pressure on the top surface of button-like samples will be calculated using a commercial software “ANSYS FLUENT” based on the finite volume method, the effects of main environmental factors (such as temperature, gas flow rate, gas pressure, oxygen partial pressure) on the oxidation resistance of ZrB2-20vol.%SiC can be revealed systematically, finally the role of air flow rate and total pressure (oxygen partial pressure) in the escape of volatile products (molten and gaseous phases), as well as in the oxide growth, microstructure, oxidation control step and active oxidation, will be explored. This project is significant for further understanding the oxidation mechanism of UHTC at ultra-high temperatures, also for developing new UHTC, high-performance protictive coatings, and non-ablative structural/functional combined thermal protection materials.