Improvement of tribological properties of C/C composites at high temperatures

Tribological properties of carbon/carbon (C/C) composites at high temperatures were investigated. Dry friction tests of C/C composites up to 10000 degrees C were performed to evaluate the effects of the temperature relating to the evaporation of adsorbed water vapor and oxidation of carbon on the friction and wear properties. Observations of sliding surfaces which compared their friction and wear properties, were also made. The function and wear of C/C composites sliding against themselves increased suddenly at about 200 degrees C, at which temperature the adsorbed water vapor is released. Although the sliding surface at 25 degrees C was flat and smooth, that of 200 degrees C war rough and covered with wear particles. The transition temperature increased with the incorporation of high-carbon-number hydrocarbons and further increased with water-soluble inorganic compounds with a high melting point. The function and wear of oxide-incorporated C/C composites with the high adsorbing capacity of water vapor was low and stable at all temperatures.