The Alkali-Metal Thermal to Electric Converter (AMTEC) is a high efficiency device for the direct conversion of heat to electricity. AMTEC is expected to contribute to energy savings if production costs can be lowered to levels that would stimulate demand for high volume production. The raw materials needed for AMTEC are common and inexpensive, but fabrication of the sodium beta"-alumina solid electrolyte (BASE) ceramic remains expensive. This project will demonstrate the feasibility of using microwave induced plasma heating to process the BASE, enhance the BASE quality, and dramatically reduce the high temperature processing time as well as the energy and dollar cost. In Phase I, plasma sintering techniques will be used to prepare BASE from precursor powders obtained from a variety of large scale suppliers. Parameters for fabricating standard size BASE tubes will be optimized using a statistically designed experimental matrix and the usual micro-analytical tools. Phase II will complete the fabrication process optimization and establish a rapid sintering test facility that will demonstrate the capability of the method and establish a clear path for large scale, low cost implementation.
Commercial Applications and Other Benefits as described by the awardee: The rapid plasma sintering process would eliminate the former requirement to encapsulate the beta"-alumina during sintering and also eliminate the need for a slow annealing step to produce complete conversion and full density. The previously high cost of the beta"-alumina, which has limited commercial prospects for AMTEC as well as for Na/S batteries, would no longer be a hindrance to commercial viability for these important emerging technologies.
