Effect of Pyrocarbon Matrix Micro-structure on Mechanical Properties of C-C Composites

The carbon carbon (C-C) composites with different pyrocarbon matrix micro-structure were obtained using PAN based carbon fiber felts infiltrated by isothermal chemical vapor infiltration (CVI) under the conditions of 1 000 ℃ and 5.0~20.0 kPa, and the effect of pyrocarbon micro-structure on the composites mechanical properties was studied. It was found that the C-C composite with monolayer lower texture prepared under 8.0 kPa displays higher breaking strength and obvious brittle fracture behavior for the stronger interface force between pyrocarbon and carbon fiber, which lead to the breaking simultaneously as loading. While the C-C composite with medium texture–high texture–medium texture prepared under 10.0~20.0 kPa shows good mechanical properties and the pseudo-plastic failure behavior, which is related to multiple crack deflections caused by the interfacial sliding between different pyrocarbon layers with a varying texture degree and the delamination micro-cracking within the highly textured pyrocarbon layer. The breaking strength of the materials reaches to 86±3 and 82±4 MPa, respectively.