Microstructure and mechanical properties of C/C composites fabricated by CLVI using toluene as precursors

With PAN-based carbon felt as preform and using toluene as precursors, carbon-carbon (C/C) composites with different microstructure were obtained by CLVI (Chemical Liquid-Vaporized Infiltration) under different temperatures. Through flexural property test, X-ray diffraction and microstructure analysis of carbon-carbon composites, it was indicated that there were close relations between microstructure, mechanical properties, fracture characteristics of C/C composites and temperature fabricating carbon-carbon composites. There were two kinds of composites fracture behaviors, namely tough fracture and brittle fracture. With different temperatures and microstructure, the composites exhibited different fracture behaviors. From the morphology of fractured surface, we can see that carbon fibers'pulling out from matrix was the major form when tough fracturing. However, the fractured surface was smooth when brittle fracturing (carbon fibers and matrix fracture at same time).