C/C-SiC复合材料表面Y_2O_3-ZrO_2-Al_2O_3涂层的涂刷法制备及其抗高温氧化性能

Preparation of Y_2O_3-ZrO_2-Al_2O_3 Coating on Carbon/Carbon Composite Materials by Slurry Method and Evaluation of Its High-Temperature Anti-Oxidation Behavior

为了提高C/C复合材料的抗高温氧化性能,用包埋法在C/C复合材料表面制备SiC内涂层,再在其上刷涂制备Y2O3-ZrO2-Al2O3多组分涂层,对制备涂层的各种影响因素进行分析,确定最佳制备工艺,并考察了该涂层的组织结构和抗高温氧化性能。结果表明:最佳制备条件为以SiC为内涂层、10%聚乙烯醇(PVA)为分散剂,以Y2O3,ZrO2,Al2O3,Si及C为原料,室温涂覆,升温到1 873 K保温30 min,反复进行5次;该涂层在1 873 K下氧化19 h,失重率仅1.76%,有良好的短期抗高温氧化性能,氧化29 h时失重率为6.23%,涂层可能已破坏失效;涂层的失效是由于其表面形成的孔洞和裂纹不能愈合而导致的。

SiC inner coating was prepared on the surface of C/C composite materials by impregnation method,and then multi- composition oxidation resistant coating Y_2O_3-ZrO_2-Al_2O_3 was fabricated atop the inner coating by slurry method.The factors influencing the preparation and performance of as-prepared composite coating were analyzed,and the optimal condition for preparing the composite coating was established.The microstructure and high-temperature anti-oxidation behavior of the composite coating were investigated.It was found that the composite layer with SiC inner layer,prepared by room- temperature coating of Y_2O_3,ZrO_2,Al_2O_3,Si and C as the starting materials in the presence of polyvinyl alcohol as the dispersant in association with 30 min of heating at 1 873 K(these processes were repeated for 5 cycles),exhibited the optimal anti- oxidation ability.Namely,its weight loss was only about1.76%after oxidation at 1 873 K for 19 h.Moreover,the failure of the as-prepared composite coating was due to the formation of bubble holes and microcracks on the surface.