(1. 北京理工大學(xué) 材料學(xué)院，北京 100081；
2. 北京航空材料研究院，北京 100095)
摘 要: 采用化學(xué)氣相沉積與等離子噴涂相結(jié)合的方法在SiC/SiC復(fù)合材料基體上制備了Si/莫來石/Er2SiO5環(huán)境障涂層。采用掃描電鏡(SEM)、能譜分析儀(EDS)與X射線衍射儀(XRD)分析其結(jié)構(gòu)變化，通過氧化試驗研究涂層在1350 ℃與1500 ℃下的高溫氧化行為。結(jié)果表明：Si/莫來石/Er2SiO5環(huán)境障涂層可在1350 ℃長時間使用，在1500 ℃短時間使用。涂層在不同高溫下的氧化失效機理不同。1350 ℃時，涂層氧化失效主要是由于涂層材料與基體材料熱膨脹不匹配使涂層中產(chǎn)生了垂直于表面的裂紋，裂紋成為元素擴散通道，加速環(huán)境中O元素擴散至粘結(jié)層與基體并將其氧化，降低了涂層與基體之間的粘結(jié)強度，從而導(dǎo)致涂層脫落。1500 ℃時，涂層氧化失效主要是元素快速擴散、反應(yīng)生成大量的氣泡狀玻璃態(tài)物質(zhì)所致。
關(guān)鍵字: Si/莫來石/Er2SiO5環(huán)境障涂層；高溫氧化；失效行為
（1. School of Material Science and Engineering, Beijing Institute of Technology, Beijing 100081, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China）
Abstract:Si/mullite/Er2SiO5 environmental barrier coatings (EBCs) were manufactured by chemical vapor deposition and plasma spraying on the SiC/SiC composites. The oxidation tests at 1350 ℃ and 1500 ℃ were carried out to study the high temperature oxidation behavior the coatings and the structure changes were analyzed by SEM, EDS and XRD. The results show that Si/mullite/Er2SiO5 EBCs can serve at 1350 ℃ for a long time but at 1500 ℃ only for a short time. The oxidation failure mechanisms vary with temperature. The failure cause of the Si/mullite/Er2SiO5 EBCs at 1350 ℃ is that the thermal expansion coefficient of EBCs cannot match well with that of the substrate, resulting in the formation of cracks in EBCs. The atoms of O diffuse through the cracks to the interface between the bond coat and substrate. As a result, the bond strength decreases due to the oxidation of the bond coat and substrate, resulting in falling off of the EBCs. The oxidation failure cause at 1500 ℃ is that elements diffuse fast and react with each other, resulting in the formation of a lot of glassy phase.
Key words: Si/mullite/Er2SiO5 environmental barrier coatings; high temperature oxidation; failure behavior
