Effect of CaO doping on corrosion resistance of Cu/(NiFe₂O₄-10NiO) cermet inert anode for aluminum electrolysis

Abstract

The CaO-doped Cu/(NiFe₂O₄-10NiO) cermet inert anodes were prepared by the cold isostatic pressing-sintering process, and their corrosion resistance to Na₃AlF₆-K₃AlF₆-Al₂O₃ melt was studied. The results show that the relative density of 5Cu/(NiFe₂O₄-10NiO) cermet sintered at 1 200 °C increases from 82.83% to 97.63% when 2% CaO (mass fraction) is added. During the electrolysis, the relative density of cermet inert anode descends owing to the chemical dissolution of additive CaO at ceramic grain boundary, which accelerates the penetration of electrolyte. Thus, the corrosion resistance to melts of Cu/(NiFe₂O₄-10NiO) cermet inert anode is reduced. To improve the corrosion resistance of the cermet inert anode, the content of CaO doped should be decreased and the technology of cleaning the ceramic grain boundary should be applied.

Keywords

aluminum electrolysis / Cu/(NiFe₂O₄-10NiO) cermet / CaO / inert anode / corrosion resistance