SiC三维编织体增强SiBCN基复合材料水氧耦合环境的抗氧化机理研究

In view of the excellent high temperature stability, high oxidation resistance and high temperature creep resistance of SiBCN ceramic, 3D SiC preform reinforced SiBCN matrix composites(3D SiC/SiBCN) are considered as the key materials for aircraft engine withstanding long-term utilization under harsh environments. 3D SiC/SiBCN composites have been fabricated in our lab. On this basis, oxidation properties and antioxidant mechanism of 3D SiC/SiBCN in air and water/oxygen coupled environment are investigated in this project. The oxidation reaction will be described by microstructure and compositions evolution of 3D SiC/SiBCN after oxidation treatment in different temperature. Moreover, oxidative kinetics is also determined by analyzing the growth of oxide layer thickness as a function of oxidation time. Furthermore, the effect of introduction BN-SiC dual layer interphase on the oxidation resistance and mechanical properties of 3D SiC/SiBCN composites are also evaluated, combining the microstructure and composition of interphase after oxidative treatment, the role of BN/SiC interphase in oxidation mechanism of 3D SiC/SiBCN is clarified. Antioxidant mechanism of 3D SiC/SiBCN composites will be clarified by means of the experiment and theory research, which can provide theoretical guidance for the development of high temperature ceramic matrix composites with excellent properties.

基于SiBNC具有优异的高温抗氧化性和抗蠕变性，申请者率先成功制备了3D SiC/SiBCN复合材料，发现其具有优异的抗氧化性，有望成为航空发动机热端结构部件的关键材料。在此基础上，本项目拟深入开展3D SiC/SiBCN复合材料在空气和水氧耦合环境中/高温的抗氧化性能及氧化机理研究；通过研究氧化过程的微观结构及组成的演变规律，揭示该复合材料的氧化反应；并通过氧化层厚度随氧化时间的增长规律，建立复合材料在不同温度的氧化动力学。特别是研究含有界面相（BN-SiC）的3D SiC/SiBCN复合材料在氧化过程界面相微观结构演变规律及其与力学性能相关性，揭示界面相（BN-SiC）在3D SiC/SiBCN复合材料抗氧化过程中的作用机制。通过本项目的研究，揭示3D SiC/SiBCN复合材料在中/高温水氧耦合环境的氧化机理、影响因素及其规律，为制备综合性能优异的高温陶瓷基复合材料提供指导。

基于航空发动机的涡轮燃烧室、叶片等热端结构部件对中高温范围（800-1500℃）耐长时间抗氧化性能材料的迫切需求，本项目提出设计BN-SiC复合界面相，研究 SiC/SiBCN 复合材料分别在空气和水氧耦合环境中在 800℃～1500℃氧化处理后的微观结构、力学性能及氧化动力学。结果表明氧化处理后复合材料的弯曲强度均有不同程度的衰减，氧化温度越高，复合材料氧化后弯曲强度保留率越高，1500℃氧化25h后，弯曲强度保留率为75.83%。复合材料氧化后形成了cristobalite氧化层以及硼硅酸玻璃自愈合相，通过氧化后单位面积重量变化的平方随氧化时间的关系，计算了复合材料在800℃～1500℃的氧化动力学，氧化速率常数分别为：1.305×10-2mg2/cm2·h（800℃）、6.17×10-3mg2/cm2·h（1000℃）、0.16203 mg2/cm2·h（1200℃）、0.13947mg2/cm2·h（1400℃）和0.24098mg2/cm2·h（1500℃). 本项目的实验结果为该材料在航空发动机热端部件的使用提供数据指导，同时也促进了国产SiC纤维的批次稳定化发展。