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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。
The three-dimensional acupuncture carbon felt was used as the preform, the C / C porous material was prepared by resin impregnation-pyrolysis process, and the porous C / C porous material was impregnated with Si and Si respectively by Reactive melt infiltration (RMI) -Mo alloy to prepare C / SiC composites. The microstructure evolution of C / C porous body was studied firstly. The results showed that the resin was mainly filled in the pores of the fiber bundles during the impregnation process. After pyrolysis, the cracks increased to form the C / C sub-structure unit. The high temperature heat treatment further expanded the cracks in the C / C composites and increased the graphitization degree , Closed within the beam hole open, so as to provide RMI osmosis Si access. Then, the phase composition and the microstructure of the material obtained by infiltration of Si and Si-Mo alloy into C / C porous material were compared. It is found that the residual Si in the composites obtained by impregnation with pure Si is more, and the fiber in the bundles is seriously damaged. However, the infiltrated Si-Mo alloy can reduce the residual Si content and the fibers in the bundles are less damaged and still maintain the complete C / C ratio Structural units.