Comparison of microstructure and flexural property of C/C composites with two kinds of carbon matrices

The microstructure and flexural property of C/C composites with pitch and pyrocarbon matrix (named as material A and B respectively) reinforced by non-woven cloth/network carbon felts were comparatively studied by polarized light microscope, scanning electron microscope and universal mechanical property machine. The results show that, for material A, the pitch carbon matrix is of continuous tiny laminar structure with numerous inter-laminar micro-cracks, resulting in the weak bond among laminas; for material B, pyrocarbon matrix consits of amounts of growth-cones, and similarly displays thick laminar structure under SEM while the bond among laminas is strong. The XY-directional flexural strength of material A was slightly lower than that of material B, but the Z-directional strength was higher. The material A presented ideal pseudo-plastic fracture characteristic in both XY and Z directions, and the material B exhibits "ladder type" fracture characteristic in XY-direction and obvious brittle fracture in Z-direction. The flexural mechanical behavior of material was greatly related to the microstructure of carbon matrix and the pore filling in carbon felt.