炭/炭复合材料表面C/SiC/Si-Mo-Cr多层复合防氧化涂层研究(英文)

为提高炭/炭(C/C)复合材料的高温抗氧化性能,采用料浆涂刷法首先在C/C复合材料表面制备了预炭层,然后以Si粉及石墨粉(Si粉与石墨粉的质量配比为:60～80:10～25)为原材料采用包埋法经高温热处理获得C/SiC内涂层,最后在涂有C/SiC内涂层的C/C复合材料表面采用包埋法制备Si-Mo-Cr外涂层。借助扫描电镜、X射线衍射、电子能谱等分析测试手段对涂层试样的微观结构进行了分析,研究了涂层C/C复合材料在1 873 K和1 973 K下的氧化行为。结果表明:由于涂层氧化过程中表面生成了SiO2和Cr2O3复合玻璃层,其在1 873 K温度下表现出优异的防氧化性能,可以有效保护C/C复合材料达135 h。当氧化温度提高至1 973 K并氧化30 h后,该复合涂层氧化过程玻璃层完整性被破坏,涂层失效。

C/SiC/Si-Mo-Cr multilayer coating for carbon/carbon composites for oxidation protection

To improve the oxidation resistance of carbon/carbon(C/C) composites at high temperature,the C/C composites were first slurry-coated by carbon,then pack cemented by mixtures of Si and graphite powder(60-80∶10-25 wt/wt),followed by heat treatment to form C/C composites coated with a C/SiC layer,and finally a Si-Mo-Cr oxidation protective coating was prepared on the surface of the these composites by pack cementation.Scanning electron microscopy,X-ray diffraction,and energy dispersive spectroscopy were used to characterize the compositions and microstructure of the coating.The oxidation behavior of the coated C/C composites at 1 873 and 1 973 K in air was investigated.The coating showed excellent oxidation resistance at 1 873 K due to the formation of a glassy layer of SiO2 and Cr2O3 during the oxidation test,which could effectively protect C/C composites from oxidation for 135 h.The coating failed after oxidation for 30 h at 1973 K because the protective glass layer was disrupted.