Cerium oxide as conversion coating for the corrosion protection of aluminum

Abstract

CeO2 coatings were formed on the aluminum after Al surface preparation, by dripping the ceria sol, previously prepared by forced hydrolysis of Ce(NO3)4. The anticorrosive properties of ceria coatings were investigated by the electrochemical impedance spectroscopy (EIS) during the exposure to 0.03 % NaCl. The morphology of the coatings was examined by the scanning electron microscopy (SEM). EIS data indicated considerably larger corrosion resistance of CeO2-coated aluminum than for bare Al. The corrosion processes on Al below CeO2 coating are subjected to more pronounced diffusion limitations in comparison to the processes below passive aluminum oxide film, as the consequence of the formation of highly compact protective coating. The results show that the deposition of ceria coatings is an effective way to improve corrosion resistance for aluminum.

Keywords

• Ceria
• Coatings
• Corrosion
• Microstructure