中文摘要：

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。

英文摘要：

The damage evolution in three dimensional carbon fiber reinforced silicon carbide （3D Cf/SiC） composites in a stressed oxidation environment was investigated by scanning electron microscopy in terms of generation and propagation of cracks. The results indicate that the main damages in 3D Cf/SiC composites in the stressed oxidation environments include cracking of SiC matrix, debonding and oxidation of pyrolytic carbon interphase, and fracture and oxidation of carbon fibers. The interphase and fibers are oxidized by oxygen through microcracks in the matrix. The fibers are elongated due to debonding and oxidation of interphase, which contribute to the propagation of cracks. The mutual promotion between the fracture of fibers and propagation of cracks provides the essential driving force for the crack extension.