RMI法制备穿刺C/C-SiC复合材料的微结构及烧蚀性能研究

以无纬布/网胎0°/90°叠层穿刺预制体为增强体,采用化学气相渗(Chemical vapor infiltration,CVI)、树脂浸渍碳化(Polymer infiltration carbonization,PIC)与反应熔渗(Reactive melt infiltration,RMI)复合工艺制备穿刺C/C-SiC复合材料,研究其微观组织及在C₂H₂-O₂焰中的烧蚀行为。结果表明：无纬布、穿刺纤维束由CVI+PIC制备的碳基体填充而形成致密C/C区域,RMI生成的SiC主要位于网胎层中,其含量37.3wt%。复合材料表面因过量硅化而形成了SiC富集层。烧蚀距离20mm、O₂:C₂H₂=2:1时,烧蚀600s后材料X-Y、Z向线烧蚀率分别为：0.8×10^_-4 mm/s、3.6×10^_-4 mm/s,比PIP工艺制备C/C-SiC材料烧蚀率小一个数量级。烧蚀面SiC富集层保护及被动氧化作用是材料具有优异抗氧化烧蚀性能的主要原因。随烧蚀距离由20mm向10mm减小,复合材料烧蚀率先缓慢变化后快速增大,烧蚀率快速增长阶段复合材料发生主动氧化烧蚀。

Microstructure and ablation properties of the pierced C/C-SiC composites

The C/C-SiC composites were prepared by chemical vapor infiltration (CVI) combined with polymer infiltration carbonization (PIC) and reactive melt infiltration (RMI) using pierced non-woven carbon fiber felt preform. The microstructure and ablation properties were investigated. The results presented that non-woven carbon fiber cloth and pierced carbon fiber bundle formed dense C/C microstructure after CVI and PIC processes. SiC matrix was mainly located in the felt after RMI process and the content was 37.3wt%. SiC-rich layer was formed on the surface of the composites. When the ablation distance is 20mm, the ablation rates on XY and Z directions of the composites are 0.8×10_^-4 mm/s and 3.6×10_^-4 mm/s, respectively. The excellent ablation performance could be owing to the passive oxidation of SiC-rich layer on the surface. With the ablation distance decreased from 20mm to 10mm, the ablation rate of the composites changed slowly and then increased rapidly, because of the active oxidation ablation of the composites.