不同纤维体积分数CVI 炭/ 炭复合材料的石墨化度

为确定不同纤维体积分数的化学气相浸渗(CVI) C/ C 复合材料的最佳热处理工艺, 以40 %、30 %、25 %三种不同纤维体积分数的针刺整体毡为坯体, 经三次CVI 后制得C/ C 复合材料, 采用X射线衍射和拉曼光谱微区分析测试了三种不同纤维体积分数的CVI C/ C 复合材料试样未经热处理及经2200 ℃、2400 ℃热处理下宏观和微区石墨化度。结果表明: 三次CVI 热解炭均为光滑层结构, 且纤维体积分数越高, C/ C 复合材料的石墨化度也越高;纤维与光滑层热解炭界面及两种不同热解炭界面在高温热处理时会发生应力石墨化, 应力石墨化程度前者大于后者, 这是纤维体积分数高的C/ C 复合材料石墨化度高的原因; 热处理温度越高, 应力石墨化程度越大。 

GRAPHITIZATION DEGREE OF C/ C COMPOSITES WITHVARIOUS FIBRE VOLUME FRACTIONS

In order to determine the proper heat t reatment temperature for C/ C composites with different fibrevolume f ractions, C/ C composites were made by needled felt with fibre volume f raction of 40 %, 30 % and 25 % densifying through three times of CVI. The graphitization degree of C/ C composites without heat t reatment and withheat t reatment at 2200 ℃and 2400 ℃was investigated by means of X-ray diff raction and Raman spectra. The resultsshow that the microst ructures of three kinds of C/ C composites are smooth laminar (SL), and C/ C composites withhigher fibre volume f raction have higher graphitization degree ; the st ress graphitization takes place at the interfacebetween fibre and smooth laminar pyrolytic carbon and different smooth laminar pyrolytic carbons and the former islarger than the later, which is the reason why C/ C composites with higher fiber volume f raction have higher graphi2tization degree. The higher the heat t reatment temperature ( HTT), the higher the st ress graphitization degree.