Microstructure and Mechanical Properties of Pitch-based C/ C Composites Fabricated by H pic Technology

With 1K PAN-based HT carbon fibers as reinforcing materials and with modulated coal tar pitch as matrix precursor,bi-directional pitch-based carbon-carbon composites were obtained by HPIC ( High-Pressure Impregnation Carbonization) technology under different carbonization pressure.Through flexural property test and microstructure analysis of carbon-carbon composites.it was indicated that there were close relations between mechanical properties of composites and carbonization pressures,composite buld densities,microstructures and interface bonding strength.There were three kinds of composite fracture behaviors,namely tough fracture,brittle fracture and their hybrid fracture ( including both tough fracture and brittle fracture) .With different bulk densities and microstructures,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 occur( carbon fibers and matrix fracture at same time) .