Influences of heat treatment on the oxidation and corrosion behavior of Cu–Ni–Fe inert anodes for aluminium electrolysis

• Published in: Journal of alloys and compounds 2020-08, Vol.832, p.154848, Article 154848
• Main Authors: Ying, Liu, Dengpeng, Chai, Wei, Wang, Dongsheng, Li, Junwei, Wang, Yudong, Liang, Zhirong, Shi
• Format: Article
• Language: English
• Subjects: Alloys; Aluminum; Casting alloys; Copper; Corrosion; Corrosion resistance; Corrosion resistant alloys; Diffusion; Diffusion rate; Electrode materials; Electrolysis; Heat treatment; Inert anodes; Metals and alloys; Microstructure; Nickel ferrites; Oxidation; Oxidation rate; Queching; Rapid-solidification; Reaction kinetics; Solid phases; Thermogravimetry
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.154848

The homogenization heat-treatments were implemented to the experimental as-cast Cux(Ni1.67Fe)100-x alloys with x = 60,52,44 wt%, which have a two-phase structure to obtain a uniform microstructure. Moreover, the oxidation kinetics of the as-cast and as-homogenized Cux(Ni1.67Fe)100-x alloys were investigated by the thermogravimetry at 850 °C under 1atm O2 atmosphere. The thermogravimetry results showed that all the samples approximately follow the parabolic law during oxidation under this condition. The homogeneous alloys have the lower oxidation rate than the as-cast alloys due to the inhibition of outward diffusion of Cu. Furthermore, the as-cast and as-homogenized 52Cu–30Ni–18Fe alloys were tested as inert anode materials in laboratory aluminium electrolysis tests. The as-homogenized 52Cu–30Ni–18Fe alloy anode performs significantly better corrosion resistance due to the formation of NiFe2O4. In the end, there is less impurity contents of Cu in the produced aluminium after electrolysis using the as-homogenized 52Cu–30Ni–18Fe alloy anode than using the as-cast 52Cu–30Ni–18Fe anode. •Cu–Ni–Fe are regarded as one of the inert anode candidate for aluminium electrolysis.•The oxidation of the Cu–Ni–Fe alloys at 850 °C, 1atm O2 follow the parabolic law.•The diffusion and oxidation mechanism changed after homogenization treatment.•The homogenized 52Cu–30Ni–18Fe anode has a better performance during electrolysis.