Effects of graphitization degree in three-dimensional needled C/SiC composites on tribological properties

Three-dimensional needled carbon/carbon (C/C) preforms were achieved after one cycle of polymer infiltration and pyrolysis (PIP). Phenolic resin or the mixture of phenolic resin and 30 wt% graphite was used as the carbon precursor. Carbon/silicon carbide (C/SiC) composites were prepared by liquid silicon infiltrating into the C/C preforms with or without high-temperature treatment (HTT). The graphitization degree of C/C preforms was improved by HTT or graphite addition, the improvement being more outstanding by the latter, which influenced phase compositions as well as distribution and facilitated the formation of friction films for the resulting C/SiC composites. The friction studies show that higher the graphitization degree, lower the wear rate and higher the coefficient of friction as well as more stable the friction curve, with a lower sensitivity of friction and wear to the velocity-pressure conditions being due to the differences in the topography and stability of friction films.