The thermal stability of sodium beta'-alumina solid electrolyte ceramic in amtec cells

摘要

A critical component of alkali metal thermal-to electric converter (AMTEC) devices for long duration space missions is the beta"-alumina solid electrolyte ceramic (BASE), for which there exists no substitute. The temperature and environmental conditions under which BASE remains stable control operational parameters of AMTEC devices. We have used mass loss experiments in vacuum to 1573K to characterize the kinetics of BASE decomposition, and conductivity and exchanger current measurements in sodium vapor filled exposure cells to 1223K to investigate changes in the BASE which affect its ionic conductivity. There is no clear evidence of direct thermal decomposition of BASE below 1273<, although limited soda loss may occur. Reactive metals such as Mn or Cr can react with BASE at temperatures at least as low as 1223K.