TITLE:
Electrochemical Degradation Mechanism of a Cermet Anode for Aluminum Production
AUTHORS:
P. Meyer, L. Massot, M. Gibilaro, S. Bouvet, V. Laurent, A. Marmottant, P. Chamelot
KEYWORDS:
Metal/Oxide Electrode, Aluminium Electrolysis, Oxidation Reaction Mechanism
JOURNAL NAME:
Materials Sciences and Applications,
Vol.10 No.9,
September
19,
2019
ABSTRACT: Tests on (NixFeyO4 - Ni1?xFexO)/(CuxNiyFez) 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, Ni0.90Fe0.10O, NiF2 and Cu2O phases, while NixFe3-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.