Newswise — With more than 30 patents, James Klett is no stranger to success, but perhaps the Oak Ridge National Laboratory researcher’s most noteworthy achievement didn’t start out so hot -- or so it seemed at the time.
“We had been making carbon-carbon composites, which are carbon fibers embedded in a carbon matrix,” said Klett, reflecting on the 1997 discovery. “Our goal was to find a less expensive way to make the composites, which showed promise for making better brakes and heat shields for electronics.”
While experimenting with a heat treatment process he modified by eliminating a couple of steps, Klett made a discovery that caused quite a stir and prompted hundreds of inquiries from scientists, academia and industry. The material he removed from the oven that spring day 18 years ago didn’t turn out the way he had expected, but it had some very attractive properties.
“I noticed that it transferred heat remarkably fast,” Klett said. Out of curiosity, he and colleagues performed tests on the material and realized that they had accidentally discovered high-conductivity graphite foam, which features a skeletal structure full of air pockets, making it lightweight and, unlike carbon foam products, extremely thermally conductive.
The process evolved into a batch method Klett compares to baking a cake.
“You put the batter in a pan, stick it in the oven and heat it to the right temperature until you get a foam, which is what a cake really is,” he said. “In our method, we put mesophase pitch, or a distilled tar, in a vessel, pressurize and heat it and let the material decompose.
“The gas generated by decomposition during pyrolysis bubbles through the viscous heated pitch, stretching the ligaments and orienting the molecules in such a way as to produce a foam with extraordinary properties.”
A couple of years after its discovery, the material won an R&D 100 Award for being one of the previous year’s 100 most significant innovations.
For Klett, who at the time was just 29, the lesson was that “a result is a result, whether it’s good or bad. We learn how to do things and how not to do things. We learn why something fails and why it succeeds.”
With three licenses and 29 U.S. patents, however, graphite foam is no failure. The material’s impressive thermal and acoustic properties have made it useful for street lights, weapon cooling, muzzle suppressors, electronics and, most recently, for LED lighting systems for sports arenas, manufacturing facilities, warehouses and large retail outlets. The possibilities seem endless.
“There are so many potential applications I just don’t have enough time to pursue them all,” said Klett, who earned bachelor’s, master’s and doctorate degrees in chemical engineering from Clemson University. He and his wife, Lynn, have three children. Outside the laboratory, Klett is active in the Boy Scouts and is an avid fisherman. – Ron Walli, April 27, 2015
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