|Prototype concentric tube atmospheric pressure plasma reactor for fiber oxidation from Atmospheric Glow Technologies.
Researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL), working as part of a consortium with Ford, General Motors and DaimlerChrysler, are working to develop high-volume renewable sources of carbon fiber feedstocks in an attempt to lower the cost of carbon fiber composites.
Major cost reductions are needed in both the precursor materials and in the conversion processes that transform precursor into finished fibers to enable more widespread application of carbon-fiber components.
The cost of commercial-grade carbon fiber is currently between $8 and $10 per pound. The consortium’s goal is to reduce that to between $3 and $5 per pound, according to Bob Norris, leader of ORNL’s Polymer Matrix Composites Group.
At that lower price range, automakers could use approximately 300 pounds of composite per vehicle.
Carbon fiber weighs one-fifth as much as steel yet is just as strong and stiff, making it ideal for structural or semi-structural components in automobiles. Replacing half the ferrous metals in current automobiles could reduce a vehicle’s weight by 60% and fuel consumption by 30%, according to some studies.
The resulting gains in fuel efficiency, made in part because smaller engines could be used with lighter vehicles, would also reduce greenhouse gas and other emissions by 10% to 20%, according to ORNL.
Preliminary results of computer crash simulations show that cars made from carbon fiber would be just as safe—perhaps even safer—than today’s automobiles. Formula 1 racers are required by mandate to be made from carbon fiber to meet safety requirements.
Project work is proceeding along several paths.
ORNL, with the support of the University of Tennessee, is optimizing raw materials and spinning processes for alternative forms of carbon fiber precursors from renewable sources such as lignin from wood pulp and cellulose..
ORNL is working with Atmospheric Glow Technologies (a University of Tennessee spin-off) on developing an efficient carbon-fiber oxidation process, which would significantly increase production and lower cost of this raw material. Oxidation is the rate-limiting step in the conversion process. A rapid oxidation process could dramatically increase the conversion line throughput and appreciably lower the fiber cost.
Atmospheric Glow specializes in atmospheric-pressure plasma processing. This is a technique to generate and to use plasmas in the open atmosphere instead of in a carefully controlled environment such as in inert gases and at very low pressures. The company’s One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) electrically breaks down air at standard pressure and ambient temperatures, creating highly reactive chemical species that can be used for a variety of applications.
ORNL is also establishing a modular carbon fiber research pilot line to evaluate these new processes on a comparable basis against conventional industrial processes.
In addition, researchers also are working to develop techniques to allow high-volume cost-effective processing of carbon fiber, hybrid glass-carbon fiber and reinforced thermoplastic material forms. ORNL recently installed an advanced preforming machine that features a robotically actuated arm that chops and sprays fiber and a binder in powder form to create fiber preforms. After being set at elevated temperature, the preforms are injected with resin in a mold and consolidated under pressure to create the final part.
ORNL: Carbon Fiber Oxidation