| A Material World: | |
| Environmentally Benign Materials and Processes | |
Improving the durability of thermal barrier coatings used in land-based, power-generating gas turbines will help make them operate more efficiently, thus reducing the world's dependence on fossil fuels.
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Such is the goal of Drs. Brent Carter and Janet Hampikian, who are incorporating thin films into thermal barrier coatings. The films are synthesized by combustion chemical vapor deposition (CCVD). The technique was developed at Georgia Tech by alumnus Dr. Andrew Hunt, who founded MicroCoating Technologies Inc. to develop and commercialize the patented process.
The researchers are studying several types of thin films for incorporation between the metallic bond coat and zirconia top coat of thermal barrier coatings. They are also investigating the effects of vacuum annealing, a process that heats the thermal barrier coating (or at least parts of the coating system) and then slowly cools it to prevent brittleness and thus improve durability. The research is funded by the U.S. Department of Energy through the South Carolina Energy Research and Development Center at Clemson University.
In another project that will benefit the environment, researchers are hoping to improve the performance of solid-state ionic devices, such as solid-oxide fuel cells, lithium batteries and gas sensors. Materials researcher Dr. Meilin Liu is engineering mixed ionic-electronic conductors (MIECs) and nanostructured, mesoporous materials to develop interfaces that offer minimal resistance to electrochemical reactions. The result will be devices with increased efficiency.
The key is structuring mesoporous material to form the MIEC-electrode portion of the interface. In effect, it would not only allow gases or liquids to pass through, but also offer an extremely large electrode area for electrochemical reactions. The significantly larger active-surface area, along with shorter diffusion lengths, means the electrode responds faster and more efficiently. The research will also advance an understanding of the principles of mesoporous MIEC electrodes. This understanding could lead to a new generation of solid-state ionic devices designed for energy storage and conversion, chemical sensing, oxygen or hydrogen separation, pollution control and partial oxidation of methane or other light hydrocarbons to synthesis gas or cleaner fuels.
In a related research project, Liu is studying the potential of MIEC-based ceramic membranes and electrodes for the electrocatalytic conversion of methane to cleaner fuels. The work is fundamental to the creation of low-pollution vehicles powered by fuel cells with natural gas as fuel, or other types of low-toxic-emission transportation. In addition, the research aims to develop membranes and thin-film structures for high-selectivity gas sensors designed to monitor and control the combustion process, and also remove certain pollutants and unburned hydrocarbons from the exhaust stream.
— Gary Goettling and Jane M. Sanders
For more information, contact:
(1) Dr. Brent Carter, School of Materials Science and Engineering, Georgia Tech, Atlanta, GA 30332-0245. (Telephone: 404-894-6762) (E-mail: brent.carter@mse.gatech.edu);
(2) Dr. Meilin Liu, School of Materials Science and Engineering, Georgia Tech, Atlanta, GA 30332-0245. (Telephone: 404-894-6114) (E-mail: meilin.liu@mse.gatech.edu)
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