Influence of operating conditions on cermet inert anode corrosion in cryolite for aluminium production. (November 2021)

• Record Type: Journal Article
• Authors: Gibilaro, Mathieu; Meyer, Pauline; Massot, Laurent; Bouvet, Sylvie; Laurent, Véronique; Chamelot, Pierre
• Is Part Of: Corrosion science. Volume 192(2021)
• Publication Date: 2021-11
• Subjects: Inert anode -- Cermet -- Spinel -- High temperature; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2021.109773
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: A (Nix Fey O4 –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 Ni0.90 Fe2.10 O4 and Ni0.90 Fe0.10 O, as observed during immersion tests. The metallic phase is partly oxidised, leading to porosity in the cermet. Highlights: Influence of operating parameters on a cermet material corrosion, candidate as inert anode, was examined in cryolite. Spinel dissolution, monoxide reduction and metal enrichment in Ni was observed during immersion under Ar, whatever CR and Al2 O3 . Under Ar, metallic sulphurs were formed in industrial grade electrolyte and Al presence leaded to spinel and monoxide reduction. Under air atmosphere, S and Al had not more influence on the cermet corrosion.