Effect of pyrocarbon content on thermal and frictional properties in C/C preforms of C/C-SiC composites

This paper concerns the influence of the phase composition (SiC, Si, and pyrocarbon) modification in the C/C-SiC composite on the thermal and friction behavior, and the related mechanisms. For this purpose, four different C/C-SiC composites with the same fiber volume but different phase contents were prepared by chemical vapor infiltration, combining with liquid silicon infiltration process, and these samples were submitted to structural and thermal characterization, then to friction and wear tests using a disk-on-disk configuration at the same condition. As a result, the composition and phase content of the C/C-SiC composites play an important role in varying thermal conductivity, wear mechanism and wear rate. The C/C-SiC composite with higher pyrocarbon content and less ceramic content showed higher transverse thermal conductivity. The friction coefficients increased with increasing SiC and Si content. The wear mechanism changed from an abrasive action to an adhesive action with increasing the Si content.