RESISTIVITY CHANGE OF CATHODE GRAPHITE DURING AND AFTER ELECTROLYSIS INrnALUMINA MOLTEN SALT

摘要

Resistivity change of cathode graphite during and after electrolysisrnin alumina molten salt was determined at different temperaturesrnbetween 870oC and 980°C. Resistivity of cathode graphiterndecreased remarkably in the initial stage of electrolysis and thenrnbecame almost constant for further electrolysis. On the other hand,rnresistivity increased with time by interrupting electrolysis. Justrnafter the interruption, resistivity increased rapidly with time,rnfollowed by a characteristic plateau, and again increased towards arnfinal steady value. Repeating of this cycle resulted in remarkablernenlargement of resistivity.rnIt should be noted that a large increasing ratio of resistivity ofrncathode graphite before and after electrolysis was observed atrnrelatively low temperature such as 870°C. This observationrnsuggested intercalated sodium is stabilized at lower temperaturernand the amount of sodium uptake increased during electrolysis.rnCorrespondingly, the electrolysis at lower temperature provides anrneffective way for evaluation on degradation of cathode graphite.