等离子喷涂制备C/C复合材料SiC涂层的驻点烧蚀性能  

Stagnation Point Ablation Property of SiC Coating for Carbon/Carbon Composites by Vacuum Plasma Spraying

作　　者：孙乐[1,2] 王成[1] 孟广慧[1] 宗彦旭 吴坤尧 丁旭[1,2] 

机构地区：[1]西安航空学院材料工程学院,西安710077 [2]西安航空学院新材料研究所,西安710077

出　　处：《表面技术》2017年第7期45-50,共6页Surface Technology

基　　金：西安航空学院校级科研基金资助项目(2015KY1105);国家级大学生创新创业训练计划项目(201611736001)~~

摘　　要：目的在C/C复合材料表面制备SiC涂层,提高C/C复合材料抗烧蚀性能。方法采用真空等离子喷涂技术在C/C复合材料表面制备纯Si涂层,在惰性气氛保护下对涂层高温热处理,纯Si涂层与C元素在高温下反应,原位生成SiC涂层。利用电弧加热器在不同烧蚀温度下,分别考核涂层的驻点烧蚀性能,并采用OM、SEM、EDS和XRD等对烧蚀前后的微观形貌和物相成分进行分析。结果在C/C复合材料表面制备了致密的SiC涂层,涂层中没有明显的裂纹存在,并在涂层下方产生较深的渗透区域,深度超过涂层厚度。制备的SiC涂层在1400℃下烧蚀50 s,涂层完整,具有良好的驻点烧蚀性能;在1600℃和1650℃下烧蚀50 s,涂层部分剥落,C/C复合材料基体产生烧蚀。结论 SiC涂层在高温下氧化成Si O2玻璃态膜,并覆盖在C/C复合材料表面,对基体具有良好的保护作用。随着烧蚀温度的提高,在超音速气流的冲刷下,由于热膨胀系数不匹配和SiC主动氧化的原因,涂层在烧蚀面边缘出现剥落,且剥落现象越来越严重,涂层失去对C/C基体的保护作用,烧蚀性能下降。The work aims to improve ablation resistance of C/C composites by preparing SiC coating on C/C composites. A pure Si coating was prepared on C/C composites by adopting vacuum plasma spraying （VPS） technology and then SiC coating was generated in situ by performing high-heat treatment in inert atmosphere as pure Si coating reacted with C element at high temperature. The stagnation point ablation property of coating was evaluated on arc heater at different temperature. Microstruc-ture and phase composition of the coating before and after ablation were characterized with optical microscopy, scanning elec-tron microscopy, energy dispersive spectroscopy and X-ray diffractometer. A compact SiC coating free from obvious cracks was prepared on C/C composites. Deep permeation zone was present beneath the coating and the depth exceeded coating thickness. As-prepared SiC coating was complete and of good stagnation point ablation property as the coating has been ablated at 1400℃ for 50 s. However, local coating peeled off at 1600℃ and 1650℃ after 50 s ablation to make the C/C composites ablated. The SiO2 glassy scale covering the surface of C/C composites is formed on SiC coating at high temperature, which can protect the C/C substrates. As the ablation temperature rises, provided with erosion of hyper-sonic flow, mismatched thermal expansion and active SiC oxidation, the temperature increasingly peels off along edges of ablated surface and cannot protect C/C substrate any more, so that ablation resistance of the coating decreases.

关 键 词：真空等离子喷涂 SIC涂层 驻点烧蚀 SIO2膜 主动氧化 C/C复合材料 

分 类 号：TB332[一般工业技术—材料科学与工程]