Development of mesophase pitch derived high thermal conductivity graphite foam using a template method

摘要

A simple and inexpensive method is described for preparing high thermal conductivity graphite foam by impregnating a coal tar pitch based mesophase pitch into a substrate polyurethane foam template. Mesophase pitch impregnated polyurethane foam was converted into graphite foam by several heat treatments in air as well as in an inert atmosphere. Scanning electron microscope images show the retention of an excellent open pore structure despite volume shrinkage of over 50%. The graphite foam prepared by this sacrificial template method is found to possess a thermal conductivity of 60 W/m K with a compressive strength in the range of 3.0-5.0 MPa. The X-ray diffraction pattern shows an interlayer spacing (d_(002)) of 0.3388 nm at a heat treatment temperature of 2400 °C. Different concentrations of slurries of mesophase pitch in water were used in combination with substrate foams of different densities to prepare graphite foams of density in the range 0.23-0.58 g cm~(-3). The specific thermal conductivity of the carbon foam with a low density of 0.58 g cm~(-3) is found to be higher than that of copper metal traditionally used in thermal management applications.