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将化学气相沉积在石墨基片上的SiC-BxC复合涂层在O2(8kPa)/H2O(14kPa)/Ar(78kPa)的模拟气氛中,分别加热到700,1000℃和1200℃处理10h。利用扫描电镜、X射线衍射、能谱分析、显微Raman和Fourier变换红外光谱仪研究其微观结构。结果表明:复合涂层中的BxC层在700～1000℃的模拟环境中会被完全氧化成B2O3和H3BO3;在1000～1200℃的模拟环境中,BxC层的氧化产物迅速挥发。经高温模拟环境处理后,复合涂层中生成了硼硅酸盐玻璃,且各氧化产物和SiC层的结晶度随处理温度的升高而下降。基于微观分析结果,对SiC-BxC复合涂层的自愈合抗氧化性能进行了分析。
The SiC-BxC composite coating deposited on graphite substrate by chemical vapor deposition was heated to 700, 1000 ℃ and 1200 ℃ for 10h under the simulated atmosphere of O2 (8kPa) / H2O (14kPa) / Ar (78kPa) respectively. The microstructure was investigated by scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy, Raman microscopy and Fourier transform infrared spectroscopy. The results show that the BxC layer in the composite coating is completely oxidized into B2O3 and H3BO3 in the simulated environment of 700-1000 ℃, and the oxidation products of the BxC layer volatilize rapidly in the simulated environment of 1000-1200 ℃. The borosilicate glass was formed in the composite coating after the high temperature simulated environment treatment, and the crystallinity of each oxidation product and SiC layer decreased with the increase of the treatment temperature. Based on the results of microscopic analysis, the self-healing oxidation resistance of SiC-BxC composite coating was analyzed.