Method of protection of cathode blocks of aluminium electrolysis cells

Cathode wear is one of the main lifetime limiting factors of an aluminium electrolysis cell. In the present work the composition of the wettable TiB 2 -based coating and the cost-effective method of its application to protect the most defenseless areas of the cell bottom are proposed in relation with the cathode blocks wear profile and failure mechanisms. The protective coating composition comprises a mixture of TiB 2 powders with bimodal or multimodal grain size distribution (65-40 wt. %) and a water-soluble environmentally friendly binder (35-60 wt. %). The proposed TiB 2 -C protective coating is characterised by high adhesion to the cathode block material, as well as wear resistance, resistance to cracks initiation and their propagation, wettability by liquid aluminium. That leads to a contact electrical resistance decrease and an increase of a chemical resistance at the Al-TiB 2 -C interface. The developed method of the cathode blocks protection was tested in operating conditions on an industrial electrolysis cell. The expected lifetime of cathode blocks was increased at least for 4 mounts. The results are promising and show the efficiency of the proposed method for cathode blocks protection.