High thermal conductivity graphitic foam reinforced carbon-carbon composites

Graphitic foam was densified with naphthalene which was subsequently converted to graphitic carbon to form a foam reinforced carbon-carbon composite using a novel process developed by the U.S. Air Force and licensed to SMJ Carbon. The densification was performed to produce dense foam-reinforced materials of which mechanical and thermal properties could be measured. It was found that after 6 densification cycles, thermal conductivity increased by 80 W/mK in the z-direction and 50 W/mK in the x-y plane and was relatively independent of the original properties of the foam. The compressive strength also increased by a factor of 4 and was again relatively independent of initial compressive properties of the foam. The densification of carbon foams (rather than graphitized foam), followed by a graphitization, yielded foams with properties (both thermal and mechanical) similar to foams that were first graphitized and then densified. This result should serve to reduce processing costs by eliminating the first graphitization step from the process. Last, it was found that after four cycles an additional heat treatment was needed to open the pores of the matrix to permit further densification.