Optimizing cathodic electrodeposition parameters of ceria coating to enhance the oxidation resistance of a Cr2O3-forming alloy

• Electrodeposition was used to make ceria coating on a chromium oxide forming alloy;
• Deposition parameters of current density, time and temperature were investigated;
• Crystal size and morphology of coating vary with changing of deposition parameters;
• Coating prepared with optimized parameters reduced oxidation rate of alloy 230.

Nano-ceria coating was deposited onto a chromium oxide forming alloy through galvanostatic cathodic electro-deposition method in cerium nitrate electrolyte. The electrochemical behavior and influence of main deposition parameters of current density, deposition time, and temperature were studied. It was seen that the crystal size decreased with increasing of current density while micro-cracks were also observed at higher current density. Slightly increasing of crystal size and smoothing of surface morphology were seen with increasing of deposition time. It was reported that the bath temperature has the most significant effect on crystal size and surface morphology of the deposit. Green rust as corrosion product was also observed with deposition temperatures higher than 35 °C. Optimized deposition parameters were used to produce homogeneous, continuous and green rust-free coatings which enhance the oxidation resistance of alloy 230. The electro-deposition process was found to be an accessible and efficient method to prepare nano-crystalline ceria coating.