Abstract:A comparative study on the corrosion resistance of 17Ni/(NiFe₂O₄-10NiO) cermet inert anode prepared in different sintering atmospheres was conducted in Na₃AlF₆-Al₂O₃ melt. The results indicate that the corrosion rates of NiFe₂O₄-based cermet anodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 (volume fraction) are 6.46 and 2.71 cm/a, respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due to some reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of the densification layer (about 50 μm) is thicker than that (about 30 μm) formed on the surface of anode prepared in the vacuum. The contents of NiO and Fe(II) in NiFe_2xO_4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces the corrosion resistance of the material.

Key words: sintering atmosphere; corrosion resistance; NiFe₂O₄-based cermet; inert anode; aluminum electrolysis