硅蒸镀法制备低密度C/C复合材料表面SiC涂层

SiC Coating on Low Density Carbon/Carbon Composites Prepared by Silicon Evaporation

采用浆料法在低密度C/C复合材料表面制备了石墨涂层,然后利用硅蒸镀法使硅蒸气与石墨涂层反应生成SiC涂层。借助X射线衍射、扫描电子显微镜等研究了蒸镀温度、蒸镀时间、石墨涂层表面粗糙度、硅蒸发源及气氛条件对涂层微观结构、相组成、致密度、平整度以及涂层厚度的影响。结果表明:随着蒸镀温度的升高,涂层的表面平整度增加,当蒸镀温度为1550℃和1650℃时,涂层表面仅存在SiC;硅块为硅蒸发源,氩气为保护气氛均可提高涂层表面平整度;降低石墨涂层的表面粗糙度,涂层的致密度和连续性增大;随着蒸镀时间的增加,SiC涂层厚度和致密度逐渐增加。

A graphite coating was fabricated on low density carbon/carbon composites by a slurry coating technology.SiC coating was prepared using direct reaction of silicon vapor and graphite coating through silicon evaporation.The influence of evaporation temperature,evaporation time,atmosphere,silicon evaporation source and surface roughness of graphite coating on the micrograph,phase constitution,density,surface evenness and thickness of SiC coating were studied by X-ray diffraction（XRD）and scanning electron microscopy（SEM）.The results show that the surface evenness of SiC coating increases gradually with the increase of evaporation temperature.Only SiC exists on coating surface at the evaporation temperature of 1550,1650℃.Using silicon block as silicon source and argon as protective gas,the surface evenness of SiC coating is enhanced.The density and continuity of coating can be improved by reducing the surface roughness of graphite coating.With increasing evaporation time,the thickness and density of SiC coating gradually increases.