摘要
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。
Tensile-tensile fatigue tests combined with microscopic observation by scanning electron microscopy were performed to investigate the fatigue behavior of plain-woven C/SiC ceramic matrix composite in an inert atmosphere environment and two different corrosive environments at 1 300℃. The results indicate that, because of the oxidative corrosion effect, the fatigue behavior in inert atmosphere is much better than that in corrosive atmosphere. The ceramic matrix composite has poorer fatigue performance in the corrosive atmosphere environment, which has higher content of oxygen and water vapor. Fatigue loading can promote oxidative corrosion of the composite. Higher fatigue loadings induce wider cracks, and different crack widths correspond to different oxidation mechanisms and different oxidative morphologies. The content of oxygen in the corrosive atmosphere environment determines the oxidation rate of the carbon fiber. In the environment containing lower content of water vapor, the amorphous SiO2 coating reaction generated on the surface of the composite has strong mobility at 1 300℃. As a reaction barrier covering the pores and cracks of the coating, it can improve the fatigue life of the composite. But too much water vapor in the environment can cause severe oxidation of the SiC coating and accelerate the crystallization of the amorphous SiO2, and it also can react with SiO2 and form gaseous production, which leads to mass loss of the coating, and thus the fatigue life of the composite is decreased.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2009年第8期1378-1384,共7页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金10372081资助项目
关键词
平纹编织
碳磁化硅
陶瓷基复合材料
模拟环境
疲劳行为
plain-woven
carbon/silicon carbide
ceramic matrix composites
simulated environment
fatigue behavior
