Influence of operating conditions on cermet inert anode corrosion in cryolite for aluminium production
Résumé
A (NixFeyO4–Ni1−x′Fex’O)/(Cux′’Niy’’) cermet candidate as inert anode was investigated in cryolite at 960 °C. Immersion tests were performed and different conditions tested: cryolite ratio, alumina content, electrolyte quality, metallic aluminium content and atmosphere. Then, electrolysis was realised at 0.8 A cm-2 for 4 h in industrial conditions: industrial grade electrolyte, CR 2.2, saturated Al2O3, 960 °C and presence of metallic Al. The initial material composition was still present in the bulk and the phases compositions in the oxidised zone are Ni0.90Fe2.10O4 and Ni0.90Fe0.10O, as observed during immersion tests. The metallic phase is partly oxidised, leading to porosity in the cermet.
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