Abstract:The behavior of Cu-Ni-Ag-Al alloy used as anode for aluminum electrolysis was directly visualized in a twocompartment see-through cell during electrolysis, and its performances were tested at 850℃in acidic electrolyte molten salts consisting of 39.3% NaF-43.7% AlF3-8% NaCl-5% CaF2-4% Al₂O₃for 40 h in a laboratory cell. The results show that nascent oxygen oxidizes the anodic surface to form oxide film at the beginning of electrolysis. X-ray diffraction analysis of alloy surface show that the oxide film on the anodic surface consists of CuO, NiO, Al₂O₃, CuAl₂O₄and NiAl₂O₄. However, SEM image shows the oxide film is porous, loose and easy to fall into electrolyte and to contaminate aluminum. The corrosion mechanism of metal anodes was analyzed.

Key words: metal anodes; aluminum electrolysis; oxide film; porous; corrosion mechanism