Abstract:
Graphite foams were prepared from a coal tar pitch that was partially converted into mesophase.
Expandable graphite was used instead of an inert gas to ‘‘foam’’ the pitch. The resulting
foam was subjected to a series of heat treatments with the objective of first crosslinking
the pitch, and thereafter carbonizing and graphitizing the resulting foam. XRD confirmed
that the graphitization at 2600 C resulted in a highly graphitic material. The porosity of this
foam derives from the loose packing of the vermicular exfoliated graphite particles together
with their internal porosity. During the foaming process the pitch tends to coat the outside
surface of the expanding graphite flakes. It also bonds them together. The graphite foam prepared
with 5 wt.% expandable graphite had a bulk density of 0.249 g cm 3, a compressive
strength of 0.46 MPa and a thermal conductivity of 21Wm 1 K 1. The specific thermal
conductivity (thermal conductivity divided by the bulk density) of this low-density carbon
foam was 0.084Wm2 kg 1 K 1 which is considerably higher than that of copper metal
(0.045Wm2 kg 1 K 1) traditionally used in thermal management applications.
