High Surface Iridium Anodes for Molten Oxide Electrolysis

Processing of lunar regolith into oxygen for habitat and propulsion is needed to support future space missions. Direct electrochemical reduction of molten regolith is most attractive method of processing because no additional chemical reagents are needed. The electrochemical processing of molten oxides requires high surface area inert anodes. Such electrodes need to be structurally robust at elevated temperatures (1400-1600oC), be resistant to thermal shock, have good electrical conductivity, be resistant to attack by molten oxide (silicate), be electrochemically stable and support high current density. Because of high melting point, good oxidation resistance, superior high temperature strength and ductility, iridium is the most promising candidate for anodes in high temperature electrochemical processes. Two innovative concepts for manufacturing such anodes by electrodeposition of iridium from molten salt electrolyte (EL-FormTM process) are proposed. This technique is characterized by its ability to produce dense, ductile, pore-free, 99.9% pure iridium in form of complex shape components and coatings. The result of this program will be the development, manufacturing and testing of high surface iridium anodes for molten oxide electrolysis. The testing will be performed in cooperation with NASA and MIT.