Graphite blocks with preferred orientation and high thermal conductivity

Abstract

Graphite blocks were prepared from natural graphite (NG) flake and mesophase pitch powder by a hot-pressing technique at a relatively low temperature (500 °C). The effect of pitch binder content and heat-treatment temperature on the physical properties of the graphite blocks was investigated. X-ray analyses indicate that the graphite block has a highly preferred structural orientation, and field emission scanning electron microscopy and polarized light microscopy observations further prove that the graphitic layers of the graphite flakes are clearly oriented perpendicular to the hot-pressing direction. Graphitized blocks prepared from 86 wt.% NG and 14 wt.% mesophase pitch have a low electrical resistivity of 1.45 μΩ m and a high thermal conductivity of 522 W/m K, as well as a high thermal diffusivity of 396 mm 2/s in the direction perpendicular to the hot-pressing direction at room temperature.