Influence of the iron content in Cu–Ni based inert anodes on their corrosion resistance for aluminium electrolysis

Mechanically alloyed (Cu3.25Ni)100−xFex materials (x = 0, 15 and 30 wt.%) were evaluated as inert anodes for aluminium electrolysis in KF–AlF3 (700 °C) electrolyte. For x = 0, the cell voltage was unstable and high (5–6 V) due to the formation of an insulting NiFx layer at the metal–oxide interface. For x = 15 and 30, the formation of a Cu2O-rich external scale with a protective NiFe2O4-rich intermediate layer was favoured, resulting in a lower (∼4 V) and more stable cell voltage. The purity of the produced Al was 98.96, 99.31 and 99.20 wt.% for x = 0, 15 and 30, respectively.

► Mechanically alloyed Cu–Ni–Fe are evaluated as inert anodes for Al electrolysis. ► The influence of the Fe content on the electrode corrosion resistance is highlighted. ► Cu65Ni20Fe15 is identified as a promising inert anode material for Al production.