Corrosion behavior of Ce-doped Ni-10Cu-11Fe-6Al (wt%) inert anode in molten CaCl2 salt

Abstract

In this research the effect of cerium dopingon corrosion behavior of Ni-10Cu-11Fe-6Al (wt%) alloy as a novel inert anode in titanium electrolytic production was investigated. The samples, including un-doped and Ce-doped nickel-based alloys, were prepared using vacuum induction melting (VIM) process and then exposed to the electrolysis in molten calcium chloride at 900 °C at −1.6 V versus graphite reference electrode for different immersion time. The surface and cross-section of the samples were characterized using scanning electron microscopy (SEM), and their electrochemical behavior was investigated by electrochemical impedance spectroscopy (EIS). The results show that the un-doped samples have greater number of voids and porosities as compared to that of the 0.0064 wt% Ce-doped samples (as the optimum content of cerium in the alloy). Thus, the nickel-based alloy becomes less sensitive to the pitting by addition of cerium. The corrosion penetration depth reaches about 244 μm after 16 h of electrolysis in the un-doped sample, while was approximately 103 μm for the 0.0064 wt% Ce-doped sample, which is an indication that the corrosion penetration depth decreases by adding small amounts of Ce.