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采用反应熔渗法（ RMI）制备了C／C-SiC复合材料，对比研究了不同密度 C／C 预制体所制备 C／C-SiC 复合材料在1500℃静态空气环境中抗氧化性能和1500℃?室温抗热震性能，借助X射线衍射分析仪（ XRD）与扫描电子显微镜（ SEM）对C／C-SiC复合材料的相组成及微观形貌进行了分析。结果表明，密度为1.0 g／cm3的C／C复合材料孔径分布在10～100μm范围，有利于液相Si的渗入，进而可获得高致密度的C／C-SiC复合材料；而密度为1.7 g／cm3的C／C复合材料因孔径太小（＜10μm），不利于Si熔体的渗入，仅能在C／C复合材料表面形成SiC涂层。由于C／C复合材料与SiC的热膨胀系数不同，在氧化和热震试验过程易造成SiC涂层开裂，致使用密度为1.7 g／cm3的C／C预制体制备的C／C-SiC复合材料抗氧化与抗热震性能下降。而密度为1.0 g／cm3的C／C预制体制备的复合材料内部致密的SiC基体与低密度C／C复合材料形成镶嵌界面，有效缓解热膨胀系数不匹配而造成的缺陷，从而具有优异的抗氧化和抗热震性能。

In this study, two different densities of carbon/carbon ( C/C) composites modified by SiC were prepared u-sing reactive melt infiltration method ( RMI) . The phase composition, microstructure and element distribution of the as-prepared composites were characterized by X-ray diffraction ( XRD) and scanning electron microscope ( SEM) . The oxida-tion resistance and thermal shock resistance of C/C-SiC composites were investigated, and the morphology changes of the C/C-SiC composites after oxidation test and thermal shock test were observed by SEM. The results show that the sizes of pores determined the infiltrating depth of the molten Si during RMI. The C/C1. 0-SiC composites had a low initial density with large sizes ( 10~100μm) , which was beneficial to infiltration of the molten melts and improvement of the final densi-ty. The oxidation behavior and thermal shock of C/C-SiC composites were measured at 1500 ℃ in statics air. It indicated that C/C1. 7-SiC composites had a poor oxidation resistance and thermal shock resistance due to the coefficient of thermal expansion mismatch of SiC coating and C/C substrate. The mismatch would result in cracking or peeling and even failure of the coating. Nevertheless, C/C1. 0-SiC composites had a good oxidation resistance and thermal shock resistance because of the existence of multilayer interface between SiC matrix and C/C substrate, which effectively relieved the coefficient of thermal expansion mismatch of SiC matrix and C/C substrate. Therefore, the oxidation resistance and thermal shock resist-ance of C/C1. 0-SiC composites were improved significantly.