Meeting these conflicting demands will require innovations that dramatically improve heat transfer, including new materials that combine high thermal conductivity with low weight and acceptable strength. Among the many materials being considered are metallic and pitch-derived carbon foams. In June 1999, Poco Graphite of Decatur, Tex., acquired an exclusive license to manufacture the ORNL graphite foam, which it markets under the trade name PocoFoam. Producing stiff graphite foams with high thermal conductivity requires use of an intermediate-phase pitch material as a precursor. Typical manufacturing processes use a blowing technique to produce the foam.
Stabilization is both time-consuming and expensive.
ORNL's process eliminates the blowing and stabilization steps. The carbon foam is made by putting pitch in a vessel under pressurize and heating it to cause decomposition. The gas emitted during decomposition bubbles through the heated pitch, forming the foam. Results and Future Plans Materials such as diamond and graphite are good thermal conductors because their crystal structures have very few crystallographic defects. During the ORNL manufacturing process, intermediate-phase crystals align themselves along the foam's cell walls.