One of the many benefits to living in the Knoxville metro area is that Oak Ridge National Laboratory is in my backyard. As such, some of the most brilliant minds in the world are at my disposal. I’ve borne witness to the nascent stages of some of the world’s most revolutionary new technologies. I’ve toured the nation’s most advanced nanotechnology laboratories, the Center for Nanophase Materials Science and the Spallation Neutron Source. These will revolutionize our batteries and drug delivery systems, nanopores (carbon sequestration, methane recovery), DNA analysis, biofuel production, quantum computing, the improvement of catalytic techniques, and development of alloys. I’ve even viewed the world’s fastest super-computer, Titan (a room devouring behemoth designed for massive scientific computations).
One of the most interesting technologies I’ve been able to examine is a graphite-foam developed by Senior Researcher James Klett. While attempting to develop a new fabrication method for creating carbon-carbon composites, he accidentally stumbled on the foam in 1998. “We had been making [composites], which are carbon fibres embedded in a carbon matrix,” said Klett. “We were trying to find a cheaper way to make the composites,” he continued.
Klett created a graphite foam instead, which resembles a sheet of burnt grey brownies, and is extremely light. Klett says that he noticed that it also transferred heat remarkably fast. He could place the palm of one hand on one side of a two to three inch block of graphite foam, and press an ice cube in against the other side, and the foam would simultaneously cool his hand and cause the ice to melt quickly.
Klett and his colleagues in ORNL’s Material Science Division immediately began making more foam, which actually involves pouring a batter into moulds a lot like when you actually make brownies, and they ran tests on the substance. The porous nature of the substance lends itself to heat conductivity because it allows air and some liquids to pass through. Aside from the unusually high thermal conductivity, the tests revealed numerous applications. The foam has a structure filled with air pockets and a graphite crystal structure which makes it incredibly lightweight (a fifth as heavy as aluminum, yet conducts heat better), at 25% density.
The foam’s lightweight characteristics can be used in making lighter, smaller (due to the heat-transfer and heat-sink qualities) car parts, such as radiators. A lighter radiator allows for different engine configurations which would make cars more fuel efficient and aerodynamic. There is great interest amongst professional race teams, as a result. But the smaller radiators could be used as heat sinks in electric cars and in buildings as well. Klett also added that the foam has been used as a heat sink cooling computer chips at the lab, doubling their lifespans.
This lightweight nature has also piqued the interests of NASA and the Department of Defense. The substance is now being tested for use in producing the suppressors on M-4’s used by the U.S. military. Currently, according to Klett, the DOD’s problem is that the heat from firing using traditional suppressors heats the barrel of the weapon after about 200 rounds to the point in which the operator must remove and replace the barrel of the gun, “toss the old one, and then stamp out the brush fire that the barrel created, all while firing.” With a suppressor made of graphite foam, the rate of heating from firing is halved, and a suppressor made from graphite foam adds almost no weight at all to the weapon.
The Navy is also beginning to use the foam to design light-weight and smaller ships (hopefully not used on the hulls, because the material is, after all, porous), and missiles are being designed and used made with the graphite foam, reducing overheating problems and creating lighter, high-strength missiles. Klett also said that he and his team have recently discovered that the foam has extremely interesting acoustic properties (and is also being used to make more efficient silencers for guns), absorbing sound and making it undetectable to radar. Thus, the Air Force will soon be using the material in its stealth crafts.
The foam can be used to make better brakes, heat shields and to more effectively cool LEDs. The foam has been used in three different classified satellites and NASA could use the material in their space faring equipment because of the evaporative cooling qualities. The material is currently a controlled export and has not yet been classified, but the extreme interest of the DOD makes this foam nationally important and an item with revolutionary potential in a lot of fields. While no MRI machine for mice (seen it), this is just one of the many examples of the great research going on in our own backyard.