Erosion of sintered TiB2-cathodes during cathodic aluminium deposition from LiCl/AlCl3 melts

Using an aluminium dissolution/deposition electrolysis cell, TiB₂, TiB₂/TiC and TiC sintered specimens of different porosity were tested for erosion resistance on exposure to liquid electrodeposited aluminium at 700°C to determine whether cathodes coated with such materials can be applied in aluminium chloride electrolysis cells. Although not wetted by liquid aluminium, the TiC and the TiB₂/TiC composites were extensively eroded. The densest TiB₂ specimens showed the highest resistance against liquid aluminium. The erosion rate of TiB₂ specimens of different density after exposure to the test environment for over 200 h was almost identical and reached a value of 0.16 cm y^–1. The observed wear rates exceed the values predicted on the basis of published solubility data by a factor of approximately 10.