Uses For Space-Age Carbon Foam Range From Laptop Computers To Automobile Aerodynamics

Poco Graphite is expanding its product base with Grafoam, a material developed at the Department of Energy's Oak Ridge National Laboratory (ORNL) that could lead to more powerful laptop computers and better aerodynamics in automobiles.

The Decatur, Texas-based company's license allows it to produce Grafoam, a patented carbon foam with thermal conductivity equivalent to aluminum at one-fifth its weight. Because of its superior heat transfer characteristics, Grafoam could allow auto designers to place the radiator somewhere other than at the car's front end. It could also displace heavy cooling fans, metallic fins and heat sinks in electronics.

Poco Graphite's license allows it to manufacture Grafoam for heat transfer products for a wide range of applications, including cooling subsystems in electronic components and satellites. It fits neatly into Poco's portfolio of manufacturing specialty graphites and silicon carbide for electrical discharge machining, semiconductors, biomedical and glass industry products and general industry.

"We are excited to be working with our longtime associates at Oak Ridge National Laboratory to bring this one-of-a-kind material to Poco's family of specialty materials," said John Beasley, president of Poco Graphite. "We believe this unique material will spark innovative solutions to thermal energy management challenges."

Poco's specialty graphite materials were originally developed for use in the space program. Graphite and silicon carbide products have been used in space systems starting with the Voyager I mission and continuing to the Mars Microprobe Deep Space 2 mission.

Grafoam, which is nearly 100 percent graphite, features an open cell structure that improves heat transfer to a working fluid, like the coolant in a radiator. Unlike other carbon foam products, which act as insulators, Grafoam conducts -- or removes -- heat.

"This could lead to extremely efficient and lightweight heat exchangers -- like those in air conditioners -- and heat sinks for power electronics," said James Klett, one of the developers of Grafoam and a member of ORNL's Metals and Ceramics Division.

Klett and associates Tim Burchell and Ashok Choudhury see an early application being in notebook computers, for which microprocessor speeds are limited by the ability of the systems to dissipate heat. Instead of designs that require combinations of cooling fans, metallic fins/heat sinks and metallic substrates, Grafoam would provide an attractive solution in terms of efficiency, weight and reliability.

In automobile radiators, Grafoam could be used in conjunction with standard designs to dramatically improve cooling efficiency. With the improved efficiency, Klett said the radiator could be smaller and placed toward the back of the car's engine compartment or perhaps toward the rear of the car, thus allowing for more aerodynamic designs. Such designs would result in improved fuel economy and reduced emissions.

Other promising applications include evaporative cooling devices such as refrigeration units and heat pumps. Benefits would include using water as the working fluid and eliminating the need for ozone-depleting compounds such as freon. And Grafoam's ability to capture waste heat from energy-intensive applications and convert it to electricity with thermoelectric power cells could result in dramatic savings in energy costs to the nation and world. Poco has a sole commercial license to produce and sell the material and to make and sell end products based on the foam. Company officials expect limited production of Grafoam to begin in 2001.

The research was funded by ORNL's Laboratory Directed Research and Development program, an internal source of funding provided by DOE. ORNL is a DOE multiprogram research facility managed by Lockheed Martin Energy Research Corporation.