C/C复合材料增密过程孔隙结构及演化研究

Structure and evolution of pores during the densification cycles of C/C composites

采用液相增密法制得碳/碳(C/C)复合材料,用压汞仪测试不同工艺阶段材料的孔隙结构,用扫描电镜观察了不同工艺阶段C/C复合材料的孔隙形貌。结果表明:随着致密化的进行,材料孔隙孔径分布为0.01~0.30μm,0.30~10.00μm,10.00~200.00μm;碳基体经过热解、高温石墨化处理形成纳米孔,C/C复合材料烧后收缩和挥发物逸出,小孔聚集或连通形成大孔,材料中的孔隙以纳米孔和100μm级孔隙为主。

C/C composites are prepared by using felt as preforms and densifying the composites with resin impregnation-pyrolysis more times and final heat treatment.The structure and evolution of pores during the preparation are investigated by means of mercury intrusion method and SEM.The results showed that the pore-sizes of the composites during the densification cycles are mainly distributed in the three zones,0.01~0.30μm,0.30~10.00μm and 10.00~200.00μm.Nano-pores are formed by the pyrolysis and graphitization of carbon matrix.The porosity of the big pores is increased,its mechanisms are the constriction of the C/C composites and the release of the volatile gas,which resulted in the cluster of the small pores.