Abstract:NiFe₂O₄-10NiO-based cermet inert anodes for aluminium electrolysis were prepared and their properties were investigated in a lab-scale electrolysis cell. The results show that the inert anodes exhibit good performance during electrolysis in molten salt cryolite at 960 °C, but according to the analyses of phase compositions and microstructures through XRD, SEM/EDX and metallographic analysis, the metal in the anodes is preferentially corroded and many pores are produced on the anode surface after electrolysis. The preferential dissolution of Fe in the NiFe₂O₄ phase may lead to the non-uniform corrosion of NiFe₂O₄ grains. Moreover, a dense protective layer of NiFe₂O₄-NiAl₂O₄-FeAl₂O₄ is formed on the anode surface, which originates from the reaction of Al₂O₃ dissolved in the electrolyte with NiO or FeO, the annexation of NiFe₂O₄-NiAl₂O₄-FeAl₂O₄ to NiO and volume expansion. Thus, the dense NiFe₂O₄-NiAl₂O₄-FeAl₂O₄ layer inhibits the metal loss and ceramic-phase corrosion on the surface of the cermet inert anodes.

Key words: NiFe₂O₄-10NiO; aluminium electrolysis; inert anode; cermet; corrosion