中文摘要：

以三维针刺碳毡作为预制体,采用树脂浸渍-热解工艺制备C/C多孔体,然后采用反应熔体浸渍法（Reactive melt infiltration,RMI）对C/C多孔体分别浸渗Si和Si-Mo合金制备C/SiC复合材料。首先研究了C/C多孔体制备过程中的显微结构演变。结果表明,浸渍过程中树脂主要填充在纤维束内小孔隙中;热解后裂纹增多,生成网格状C/C亚结构单元;高温热处理使C/C复合材料裂纹进一步扩展,石墨化度提高,束内闭气孔打开,从而为RMI渗Si提供通道。然后对C/C多孔体分别渗Si和Si-Mo合金所得材料的物相组成和显微结构进行对比分析。发现纯Si浸渗得到的复合材料残余Si较多,束内纤维受损严重;而浸渗Si-Mo合金可以减少残余Si含量,束内纤维受损轻微,仍保持着完整的C/C亚结构单元。

英文摘要：

C/C composites were prepared by resin infiltration and pyrolysis with 3D needle-punched carbon fiber preforms.The reactive melt infiltration process was used subsequently to prepare C/SiC composites,and the liquid Si or Si-Mo alloy was used as the reactive melt.The microstructure evolution during the preparation process of C/C composites was investigated.The results indicate that resin mainly exists in the small pores of the fiber bundles.Pores become more and bigger but there are dense C/C segments within the fiber bundles after pyrolysis.High temperature treatment leads to a higher graphitization degree and makes the closed pores open,which acts as the channel for silicon infiltration.Some fibers inside the fiber bundles of C/SiC composite infiltrated by Si are damaged and much residual Si exists in big pores.When C/SiC composites are fabricated by Si-Mo infiltration,the remaining Si content is reduced,the damage of fibers inside the fiber bundles is much slighter and the C/C segments remain intact.