气体滞留时间对微波热解CVI工艺制备C/C复合材料性能的影响

以炭毡为预制体, N₂为稀释气体, 甲烷为炭源前驱体, 其分压为10kPa, 沉积温度为1100℃的工艺条件下,研究了不同的气体滞留时间(0.05、0.1、0.15、0.2s)对微波热解CVI工艺制备炭/炭复合材料的致密化速率、样品的体积密度及其密度均匀性的影响, 并对其组织结构进行了观察. 分析了气体的滞留时间对微波热解CVI工艺制备炭/炭复合材料的影响规律及组织结构的变化. 结果表明: 采用微波热解CVI工艺在1100℃90h内制备出体积密度为1.70g·cm^-3的炭/炭复合材料, 在滞留时间为0.15s时预制体呈现从内到外逐步致密的规律. 同时, 随着滞留时间的延长, 热解炭的组织结构从低织构到中等织构变化.

Influence of Gas Residence Time on Properties of C/C Composits Prepared by Microwave Pyrolysis CVI

The infiltration of carbon fiber preforms was studied by microwave pyrolysis chemical vapor infiltration technique, CH₄ as the carbon source gas, and N₂ as diluent gas, at 1100℃ and methane partial pressure of 10kPa with residence time of 0.05,0.1,0.15 and 0.2s, respectively. The textures of samples were observed, the densification rules of microwave pyrolysis CVI were analyzed by densification rate and radial--direction density distribution with different residence time. Results show that carbon fiber preforms can be densified from inside to outside at 1100℃ for 90h, with gas residence time of 0.15s, the carbon/carbon composite has a higher bulk density of 1.70g·cm^-3. Simultaneously, polariscope images show that the textures of the pyrocarbon change from low-textured to medium-textured with the extending of residence time.