C／SiC复合材料应力氧化失效机理

Failure Mechanism of C/SiC Composites under Stress in Oxidizing Environments

研究了干氧和湿氧两种气氛、疲劳和蠕变两种应力下C／SiC复合材料在1300℃的应力氧化行为,试验结果和断口形貌SEM分析表明:C／SiC复合材料在疲劳应力下比在蠕变应力下具有更强的抗氧化能力和更长的持续时间;干氧环境中的蠕变试样以C纤维氧化失效为主;水蒸气的存在加剧了SiC基体的氧化,并且使受蠕变应力的C／SiC复合材料以SiC基体氧化失效为主.

Stressed oxidation testing on C/SiC composites in dry and wet oxygen environments under cyclic and constant stress was conducted in the present study. Experimental results and microstructures of fracture surfaces analyzed by SEM show that the C/SiC composites have a better oxidation resistance and a longer life under fatigue testing than under creep testing. In dry oxygen environment, the failure of C/SiC composites under creep testing is mainly due to the oxidation of carbon fibers. While in wet oxygen ambient, the fracture of C/SiC composites under creep testing is caused by the failure of SiC matrix because the water vapor accelerates the oxidation of SiC.