Effect of high temperature treatment on the structure and thermal conductivity of 2D carbon/carbon composites with a high thermal conductivity

High thermal conductivity carbon/carbon composites (HTC-C/Cs) have a high specific modulus and a low thermal expansion in addition to all the excellent properties of traditional C/C composites, which have been a research focus in recent years. 2D HTC-C/Cs were prepared by hot pressure molding, densification by precursor impregnation and pyrolysis, and then heat treatment at high temperatures, using pitch-based carbon fiber fabric with a high thermal conductivity as reinforcement and mesophase pitch as the binder precursor. The structure and morphology of pitch-based carbon fibers and 2D HTC-C/Cs were investigated by XRD, SEM and TEM. The thermal conductivity was measured by laser-flash diffusivity. Results show that with increasing heat treatment temperature the crystallite size increases, the degree of order is improved, the thickness of laminar graphite around the carbon fibers increases, and the number of interfacial cracks between the fiber and matrix decrease and cracks between matrix layers are expanded. A linear relationship between thermal conductivity and heat treatment temperature was observed and the highest thermal conductivity was 443 W/m·K after heat treatment at 3 000 °C.