Author(s)

P. Meyer¹, L. Massot^1*, M. Gibilaro¹, S. Bouvet², V. Laurent², A. Marmottant², P. Chamelot¹

¹Laboratoire de Génie Chimique, Université de Toulouse, UPS-CNRS-INPT, Toulouse Cedex, France.
²Rio Tinto, Aluval, Voreppe Cedex, France.

Tests on (Ni_xFe_yO₄ - Ni_1?xFe_xO)/(Cu_xNi_yFe_z) cermets, considered as promising anode for the aluminium production, were performed under electrolysis at 0.8 A·cm^-2 in molten mixture of cryolite at 960°C. In order to predict phase compositions, a thermodynamic study was performed and experimentally verified by SEM-EDS analysis. The metallic phase oxidation leads to the formation of different phases such as FeF₂, Ni_0.90Fe_0.10O, NiF₂ and Cu₂O phases, while Ni_xFe_3-xO₄ spinel is continuously enriched up to x = 0.90, the thermodynamically stable nickel composition. When the cermet material is fully oxidized, metallic and oxide phases are converted into soluble or non-conductive phases, leading to the end of anode service life.

Metal/Oxide Electrode, Aluminium Electrolysis, Oxidation Reaction Mechanism

Meyer, P. , Massot, L. , Gibilaro, M. , Bouvet, S. , Laurent, V. , Marmottant, A. and Chamelot, P. (2019) Electrochemical Degradation Mechanism of a Cermet Anode for Aluminum Production. Materials Sciences and Applications, 10, 614-629. doi: 10.4236/msa.2019.109044.