Abstract
The resistivity of graphite cathode in alumina molten salt was determined along with electrolysis at 945°C. The resistivity decreased monotonically with the progress of the electrolysis and finally reached to a steady value. For HTT-2000 cathode graphite, the steady value was about 70% of that of the original one before electrolysis. The resistivity turned to increase from the steady value just after interruption of the electrolysis current. A characteristic 2-step curve was observed in the resistivity vs. time plot. It increased fairly steeply at first and then became almost constant at a value corresponding to 87-88 % of that of the original value. The resistivity again increased after the plateau and finally returned to the original value. Several experiments including SEM and X-ray diffraction measurements showed that the resistivity change is closely related to the intercalation and de-intercalation of sodium. For HTT-2400 and -2800 cathode graphite, sodium concentration fixed in the matrix after electrolysis was less than that of HTT-2000.
