Ablation behavior and thermal conduction mechanism of 3D ZrC–SiC-modified carbon/carbon composite having high thermal conductivity using mesophase-pitch-based carbon fibers and pyrocarbon as heat transfer channels

A three-dimensional ZrC–SiC-modified Carbon/Carbon composite having high thermal conductivity is prepared to significantly reduce the ablation rate and improve dimensional stability of composites used in thermal protection systems. The mesophase-pitch-based carbon fibers/pyrocarbon skeleton is designed as the thermal diffusion channel using the intermediate state mesophase-pitch-based carbon fibers and chemical vapor infiltration method. After successive graphitization and polymer precursor impregnation and pyrolysis, the obtained ZrC–SiC-modified carbon/carbon composite exhibits a high thermal conductivity of 206.5 W m−1 K−1 in the X(Y) direction. The ablation results indicate that the composite exhibits a surface temperature of 241 °C, which is lower than that of the composite without mesophase-pitch-based carbon fibers, thus verifying the improved ablation resistance. The linear and mass ablation rates of the composite are found to be 0.33 μm s−1 and 0.56 mg cm−2 s−1, respectively. The thermal conduction mechanism of the ZrC–SiC-modified carbon/carbon composite near the ablation center is investigated to show the combined phonon heat conduction and thermal radiation. This study provides a protocol for the design and construction of modified carbon/carbon composites having high thermal conductivity for application in hypersonic vehicles.