Preparation of TiB_2 Inert Cathode by Electrodeposition Process for Aluminum Electrolysis

摘要

The TiB_2 as inert cathode for aluminum electrolysis was electrodeposited successfully on graphite cathode as a coating by way of K_2TiF_6-KBF_4-KF-KCl molten salts electrolysis at 820 □ for 4 hours with current density (CD) 0.3~0.8A/cm~2. The composition of the electrolyte used was 15.3 K_2TiF_6, 24.2 KBF_4, 53.1 KF, 7.4 KCl in % as mass fraction. XRD was used to detect the composition of the coating with SEM used for morphology observation. The results showed that the coating with current density of 0.3～0.5A/cm~2 was composed of pure TiB_2 with no impurity. The 0.2 mm thick TiB_2 coating was smooth and appeared silvery metallic luster, especially it was bonded firmly to the graphite substrate. The distribution of Ti element was well-proportioned. It is confirmed that Ti and B can be co-deposited to form TiB_2 coating on graphite cathode surface as an inert cathode in this way. The penetration of sodium and electrolyte into the TiB_2 coating used as cathode of aluminum electrolysis was studied also. After 8 hours electrolysis, the results showed that TiB_2 coating decreased sodium penetration effectively, but the penetration mechanism has not been changed.