疲劳氧化环境中3D SiC_f/SiC复合材料损伤演变

Damage evolution in 3D SiC_f/SiC composites in fatigueoxidation environment

研究了疲劳氧化环境中3D SiCf/SiC复合材料损伤演变,并对该环境中SiCf/SiC复合材料的失效机制进行了分析。结果表明,疲劳氧化环境中3D SiCf/SiC复合材料的损伤主要为:基体开裂;热解碳界面相脱粘、氧化及取向性排列;纤维断裂、氧化及其结构的改变。这些损伤使氧化性气体通过基体开裂形成的裂纹不断氧化复合材料内部;界面相脱粘和取向性排列使纤维更容易拔出;纤维的氧化、纤维中无定形碳的增多以及SiC晶粒的长大导致纤维强度降低。

The damage evolution in 3D SiCf/SiC composites in the fatigue-oxidation environment was investigated,and the failure mechanism of SiCf/SiC in such environments was also discussed.The results indicate that the main damages in SiCf/SiC composites in fatigue-oxidation environments include： cracking of SiC matrix;debonding,oxidation and ordering of pyrolytic carbon（PyC） interphase;fracture,oxidation and change in microstructure of the fiber.The composite interior is oxidized by the oxidizing atmosphere infiltrating the composites through the cracking matrix.The fibers are pulled out more easily due to the debonding and ordering of PyC interphase.The strength of the fibers is decreased because of the oxidation of the fibers,the increase of the amorphous carbon and the growth of the SiC grain in the SiC fiber.