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PUBLIC RELEASE DATE:
5-Aug-2014

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Contact: Ron Walli
wallira@ornl.gov
865-576-0226
DOE/Oak Ridge National Laboratory
www.twitter.com/oakridgelabnews

Story tips from the Department of Energy's Oak Ridge National Laboratory, August 2014

To arrange for an interview with a researcher, please contact the Communications staff member identified at the end of each tip. For more information on ORNL and its research and development activities, please refer to one of our media contacts. If you have a general media-related question or comment, you can send it to news@ornl.gov.

MATERIALS Transparent ballistic results

Glass used for military vehicle windshields is being put to the test by an Oak Ridge National Laboratory team evaluating different formulations for mechanical strength, high pressure and shock response. The goal of the team, headed by Andy Wereszczak, is to identify compositions featuring satisfactory transparency, low density and the ability to be cost-effectively fabricated into large thick sheets. The work, being performed for the U.S. Army Tank Automotive Research, Development and Engineering Center in Warren, Mich., takes advantage of ORNL's unique instruments, capabilities and expertise. Ultimately, this research is expected to explain why various glasses yield substantially different ballistic impact performance and different failure and fracture phenomena. [Contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]

ENERGY CO2 to the rescue

Tomorrow's commercial refrigeration systems -- like the ones in supermarkets could be cooled by carbon dioxide instead of hydrofluorocarbons, a greenhouse gas that is nearly 4,000 times more potent than CO2. That is important because millions of pounds of HFCs leak into the environment every year, said Brian Fricke, a researcher in Oak Ridge National Laboratory's Building Equipment Research Group. To address the problem, Fricke and colleagues are experimenting with CO2 and other refrigerants, including a hydrofluoroolefin called R1234yf. While by definition CO2 has a global warming potential of 1, the hydrofluoroolefin's is 4, so both are far less harmful to the environment than HFCs with a rating of 3,900. Still, while CO2-based systems work well in cold climates, they aren't as efficient in warmer climates, so Fricke is experimenting with various approaches to address the limitation. [Contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]

NUCLEAR Graphite put to the test

Conclusions drawn from previous oxidation studies for nuclear grade graphite cannot be extrapolated to new versions of the material, which is an integral component of high-temperature gas-cooled reactors. This was a key finding of a study led by Oak Ridge National Laboratory's Cristian Contescu and published in the Journal of Nuclear Materials. Researchers looked specifically at the behavior of nuclear graphite in contact with traces of moisture at the high temperatures associated with gas-cooled reactors. The research showed that differences in raw material, microstructure and purity have a significant effect on the oxidation and slow degradation rates. This information is vital to the industry as new formulations of nuclear grade graphite, a moderator and major structural component in HTGRs, are developed. The paper is available at http://dx/doi.org/10.1016/j.jnucmat.2014.07.009. [Media contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]

MANUFACTURING Low-cost 3-D feedstock

Reformulated plant matter could be at the roots of a revolution in 3-D printing projected to hit $5.2 billion by 2020. Soydan Ozcan, a researcher in Oak Ridge National Laboratory's Carbon and Composite Group, leads a team that is testing plant material that has been reformed into neatly woven nanoscale crystals and fibers. Mixed with various plastics, including those that are bio-based, these needle-like crystals can produce feedstock polymers for 3-D printers with stiffness improvements already a factor of three over widely used structural materials. They are also less expensive and mostly biodegradable. Potential applications include fuel-efficient car parts, batteries, packaging and building materials, furniture, disposable electronics and bulletproof suits. [Contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]

BATTERIES Better graphite anodes

Lithium-ion batteries for cars, phones, laptop computers and other devices could retain their charge more effectively and last longer because of a method developed at Oak Ridge National Laboratory. By employing a proprietary additive to the furnace gas used during processing of natural graphite, the ORNL team produced anodes that enable a coin cell to retain up to 75 percent of its charge capacity after 1,600 to 2,000 cycles. This represents a significant improvement over the baseline version's 67 percent after 1,400 cycles. Researchers noted that their patent-pending technique stabilizes the graphite surface, reduces cost and lowers temperature requirements. These advances allow processing to be done with less expensive furnaces and less energy. The method could also help the U.S. graphite industry gain a competitive edge over overseas sources. Findings were published in the journal CARBON. [Contact: Ron Walli, (865) 576-0226; wallira@ornl.gov]

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