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通过拉–拉疲劳试验并结合电镜扫描观察,对比研究平纹编织C/SiC陶瓷基复合材料在1300℃惰性气氛环境和两种腐蚀气氛环境中的疲劳行为。结果表明:由于高温氧化腐蚀的作用,1300℃下腐蚀气氛环境中C/SiC陶瓷的抗疲劳性能明显比惰性气氛环境差,而且氧气和水分含量越高,陶瓷基复合材料在腐蚀气氛环境中的抗疲劳性能越差。疲劳载荷对氧化腐蚀起着推动作用,疲劳载荷越大裂纹宽度越大,不同的裂纹宽度对应着不同的氧化机制,从而产生不同的氧化形貌。腐蚀气氛环境中的氧气含量决定着C纤维的氧化速度。水分含量低时,于1300℃在涂层表面生成无定形态的SiO2对裂纹具有封填效果从而提高材料寿命;水分含量高时不仅促使SiO2大量析晶减弱其封填效果,而且其会与SiO2反应生成气态产物,大量消耗涂层,降低材料寿命。
The fatigue behavior of plain weaved C / SiC ceramic matrix composites was investigated in a 1300 ℃ inert atmosphere and two corrosive atmospheres by pull-pull fatigue test combined with SEM observation. The results show that the fatigue resistance of C / SiC ceramics in 1300 ℃ corrosion atmosphere is obviously worse than that in inert atmosphere and the higher the oxygen and moisture content, the corrosion resistance of ceramic matrix composites in the environment of corrosive atmosphere The worse the fatigue resistance. The fatigue load plays a promoting role in the oxidation corrosion. The larger the fatigue load is, the larger the crack width is. Different crack widths correspond to different oxidation mechanisms, resulting in different oxidation morphologies. The oxygen content of the corrosive atmosphere determines the oxidation rate of C fibers. When the moisture content is low, amorphous SiO2 forms on the surface of the coating with sealing effect at 1300 ℃ to improve the material life. When the moisture content is high, it not only promotes the SiO2 crystallization, but also weakens the sealing effect with SiO2. The reaction generates gaseous products that consume large amounts of coating and reduce the life of the material.