2D-Cf/SiC复合材料蠕变断裂及损伤机理研究

摘要

研究了2D-Cf/SiC复合材料在空气中,温度分别为700℃和900℃,蠕变应力分别为50MPa、75MPa和100MPa条件下的蠕变断裂及损伤机理.运用拉森-米勒参数法拟合材料的蠕变断裂时间,使用扫描电子显微镜分析其微观组织和断口形貌以进一步揭示其蠕变断裂机理.结果表明:2D-Cf/SiC复合材料的蠕变断裂寿命与温度和应力密切相关,较高温度或应力会降低材料的蠕变断裂寿命;在蠕变过程中,材料除发生应力损伤外,还会发生氧化损伤;2D-Cf/SiC复合材料的氧化损伤比应力损伤对蠕变断裂时间有更显著的影响.%The tensile creep rupture and creep damage mechanism of 2D-Cf/SiC composite were investigated in present work in air. The applied temperatures are 700℃ and 900℃ , and the stresses are 50MPa, 75MPa and 100MPa, re-spectively. The creep rupture time of the material was fitted by Larson-Miller equation. The microstructures and fracture morphology were analyzed by a scanning electron microscopy. The results show that the rupture time of the 2D-Cf/SiC composite was influenced by the applied stress and temperature. Higher stress or temperature causes the shorter creep rup-ture time. During the creep, the oxidation plays critical role in determining the creep rupture time. The creep damage of 2D-Cf/SiC resulted from stress and the oxidation. Compared with the former, the damage caused by the latter made a more significant effect on the creep rupture time of the composites.