Electrochemical Behaviour of Cu-Al Oxygen-Evolving Anodes in Low-Temperature Fluoride Melts and Suspensions

Cu-based alloys have been considered as promising candidates (along with the Fe-Ni alloys) for the inert anodes material in aluminium reduction cells with low-temperature electrolytes. However, low purity of aluminium due to the contamination by anode corrosion products is a problem yet to be solved. Introduction of alumina suspension as an electrolyte has been presented recently as a possible solution for providing commercial purity aluminium produced with the metallic anode. An attempt to characterize the CuAl-based anodes electrochemical performance in KF-AlF3-Al2O3 melts and suspensions has been made and presented. The effects of the suspension (or melt) properties, the anode composition and the temperature on the electrochemical behaviour of the anode and the kinetics of the oxide layer formation during polarization are studied. The 90Cu-10Al anode in the KF-AlF3-Al2O3 suspension with the cryolite ratio 1.3 and the dispersed phase volume fraction not more than 0.12 is found to be the good option for further investigations.