Process and properties of C/C composites by chemical liquid-vaporized infiltration

The large size of C/C composites (Ø110 mm × 25 mm) with a density of 1.67 g/cm³ were fabricated by chemical liquid-vaporized infiltration with and without catalyst at 1000°C for 10 h and 900°C for 8 h, respectively. The C/C composite with catalyst consists of smooth laminar and isotropic pyrocarbon, and exposes a pseudo-plastic pattern with a rough step-like fracture surface morphology, while the C/C composite without catalyst exhibits cone-like rough laminar pyrocarbon, and presents brittle fracture. In the case of catalyst, the deposition temperature and period are reduced due to the increase of nucleation sites of carbon deposition. Both flexural strength and modulus decrease and graphitization degree increases by heat treatment. Compared to the C/C composite with catalyst, the higher mechanical properties and graphitization degree are found for the C/C composite without catalyst.