原位法制备C/C复合材料SiC/Si-Al_2O_3-mullite复合抗氧化涂层

SiC/Si-Al_2O_3-mullite Oxidation Protective Coating for C/C Composites Prepared by In-situ Formation Method

以Si和Al2O3为原料,采用原位生成法在带有SiC内涂层的炭/炭（C/C）复合材料表面制备出Si-Al2O3-mullite（莫来石）抗氧化涂层。采用X射线衍射、扫描电镜和氧化实验研究了Al2O3含量等工艺因素对Si-Al2O3-mullite涂层的物相组成、结构形貌、抗氧化性能影响。结果表明：Al2O3质量含量为30%-40%时,涂层主要由Si,mullite和Al2O3三相组成,涂层致密无裂纹,抗氧化性能最佳。在1 500℃等温氧化测试显示,SiC/Si-Al2O3-mullite复合涂层比单一的SiC涂层抗氧化性能有明显提高,1 500℃等温氧化75 h试样失重为4.6%。涂层试样失重的主要原因是涂层中产生了不可愈合的孔隙缺陷。

A Si-Al2O3-mullite oxidation protective coating was prepared on SiC coated carbon-carbon （C/C） composites by in-situ formation using Si and Al2O3 as raw materials in an oxidation atmosphere. The effects of the Al2O3 content on the phase component, microstructures, and oxidation-resistance property of the Si- Al2O3-mullite coating were studied. Results show that the coating is dense and composed of Si, mullite, and Al2O3 when the content of Al2O3 is 30 wt %-40 wt % . The oxidation test indicates that the SiC/Si-Al2O3-mullite coating can protect C/C composites from oxidation in air for 75 h at 1 500℃ with a weight loss of 4.6%, which shows that the anti-oxidation ability of the SiC/Si-Al2O3-mullite coating has obviously been improved as compared with that of single-layer SiC coating. The weight loss of SiC/Si-Al2O3-mullite coated C/C composites is primarily due to the formation of holes on the coating surface.