The Grain Size Effect on Thermo-chemical Properties of AMTEC electrodes

The lifetime of alkali metal thermal to electric converter (AMTEC) is desired to last for a long time, 15 years or more, which depends primarily on thermo-electro-chemical character of electrode materials used. This study aims at the performance of electrodes by looking into their material properties mainly pertaining to the grain growth with respect to time in the grain mobility model. The electrode material studied in this work is Moybdenum. If the grain size of the electrode material reaches a certain dimension, about 500 nm, the power output starts degrading fast. It is found that Moybdenum electrodes have least power degradation for AMTEC designed for operation at the lower side of temperature, less than 1100 K as its grain growth becomes too rapid when operated above 1100 K.