定向脉冲气流TG-CVI法致密C/C复合材料工艺及性能

以液化气为碳源前驱体,氮气为稀释气体,采用定向脉冲气流TG-CVI法,对初始密度为0.14 g·cm^－3的普通碳毡进行致密化处理.研究在不同试验条件下C/C复合材料的致密化过程和密度分布,借助偏光显微镜观察其微观组织,扫描电子显微镜观察其断口形貌,采用三点弯曲法测定C/C复合材料的抗弯强度.结果表明:在热端温度为1 080 ℃、脉冲压力为－3~0 kPa的条件下,经70 h致密化,C/C复合材料的表观密度可达1.836 g·cm^－3,且密度分布均匀;组织为粗糙层(RL)和光滑层(SL)的混合型组织;试样断口形貌呈渐变的锯齿状分布,纤维以拔出为主,表现为假塑性断裂特征,抗弯强度为83.91 MPa.

Technological process and performance of C/C composites densified with directional pulse airflow TG-CVI method

Taking the liquefied gas as carbon source precursor and the nitrogen as dilution gas, the general carbon felt with initial density of 0.14 g·cm^－3 was densified by means of directional pulse airflow TG-CVI method. The densification process and density distribution of the C/C composites were studied under different experimental conditions. The microstructure, fracture morphology and flexural strength of the C/C composites were investigated by using polarized light microscopy, scanning electron microscopy and three-point bending method. The result showed that under condition of hot side temperature of 1 080 ℃ and pulse pressure of -3~0 kPa, the appearance density of the C/C composites after densified for 70 h would be 1.836 g·cm^－3 with uniform density distribution. The microstructure would be a mixed structure of rough laminae(RL) with smooth laminae(SL).The fracture morphology of the samples would exhibit a progressive serrated distribution and the fibers would mainly be of pullout, showing a pseudoplastic fracture feature. In addition, the flexural strength would be 83.91 MPa.