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以裂纹的产生和扩展为线索,通过扫描电镜研究了疲劳氧化环境中3DCf/SiC复合材料损伤演变特征。结果表明:应力氧化环境中3DCf/SiC复合材料的损伤形式主要为:基体开裂,界面相脱粘和氧化以及纤维的氧化与断裂。基体开裂为氧化性气体与复合材料内部的界面相和纤维反应提供通道。界面相脱粘和氧化导致纤维伸长量增加,促使裂纹扩展。纤维氧化断裂和裂纹张开扩展相互促进,形成了裂纹扩展的动力。
Taking the generation and propagation of cracks as a clue, the damage evolution of 3DCf / SiC composites under fatigue oxidation was investigated by scanning electron microscopy. The results show that the main damage modes of 3DCf / SiC composites in stress-oxidation environment are matrix cracking, interfacial phase debonding and oxidation, and fiber oxidation and fracture. The cracking of the matrix provides a pathway for the oxidizing gas to react with the interfacial phase and the fiber within the composite. Interfacial phase debonding and oxidation lead to increased fiber elongation, prompting crack propagation. Oxidation of fiber and crack expansion open to promote each other, forming a crack propagation power.