EFFECTS OF PROCESSING METHODS AND PARAMETERS ON THE MECHANICAL-PROPERTIES AND MICROSTRUCTURE OF CARBON CARBON COMPOSITES/

The influence of the fabrication parameters during carbonization and d ensification processes on the mechanical properties and the microstruc ture of carbon/carbon (C/C) composites were investigated. The C/C comp osites were made by using phenolic resin as precursor and two-dimensio nal carbon fabrics as reinforcements for the first carbonization. The effects of heating rate and heat-treatment temperature during the init ial carbonization process on the properties of C/C composites are pres ented. Further densification treatment was completed by chemical vapou r infiltration (CVI) and a liquid-resin impregnation process. The CVI route was found to be more efficient than the resin-impregnation proce ss. The interlayer spacing of C/C composites did not change after resi n re-impregnation for several times. However, the interlayer spacing o f the C/C composites was reduced when the processing temperature in th e CVI process was increased. Higher flexural strength and flexural mod ulus were obtained because the densities of the composites were enhanc ed either by the chemical vapour infiltration process or by the resin- impregnation route. The variation in thickness of the CVI deposited ca rbon within the preformed composite was studied and the morphology of the fracture surface of the C/C composites was also examined,