三维针刺C/SiC复合材料显微结构演变分析

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。

Microstructure evolution of 3D needled C/SiC composites

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 ...