Abstract: The thermal conductivity of C/C composites at different temperature are discussed.It has been found that the thermal conduction mechanism of C/C composites is intervenient between metal and nonmetal materials, which can be explained by using the phonon heat conduction and the electron heat conduction. The thermal conductivity of C/C composites tends to go up with the increasing of the absolute temperature under the experimental condition. With the increasing of the graphitization degree, the microstructure of the crystal is perfected gradually and the arrangement of laminar graphite is ordered perfectly as well, which leads to the enhancement of the thermal conductivity of C/C composites. C/C composites of high densities have higher thermal conductivity due to their excellent connectivity between crystal particles and smooth channels for the movement of heat conduction carriers. Carbon fibers and pyrocarbon deposited around them are the major paths of heat conduction, so the thermal conductivity increases along the orientation of the carbon fiber.

Key words: carbon/carbon composites, thermal conductivity, laser pulse method, phonon mean free path, graphitization degree, connectivity