Effect of Copper on the Microstructure and Properties of Phosphorus Cast Iron for the Anode of Aluminum Electrolyzer

The effect of copper content on the microstructure and properties of Phosphorus Cast Iron for the anode of aluminum electrolyzer is studied in this paper. After adding 0.41–1.52 wt.% Cu in Phosphorus Cast Iron and heated at 800 °C for 24 h, the matrix microstructure of samples is ferrite, and the graphite and phosphorus eutectic are refined. The impact toughness increases from 0.69 to 0.81 J/cm². The bulky sheet graphite can increase scattering probability of electron which will increase the electrical resistivity of cast iron. The resistivity of samples with 0.41–1.52 wt.% Cu (9.21 × 10⁻⁷–9.77 × 10⁻⁷ Ω m) is evidently lower than that of sample without Cu (1.12 × 10⁻⁶ Ω m). The resistivity increases initially and then decreases with increasing Cu content. The average thermal expansion coefficients between 20 and 800 °C of samples with 0.41–1.52 wt.% Cu are changed in 14.03 × 10⁻⁶–15.15 × 10⁻⁶ K⁻¹ [slightly larger than that of sample without Cu (13.72 × 10⁻⁶ K⁻¹)]. The high temperature oxidation resistance and corrosion resistance are also improved with the addition of Cu.