Cerium oxide as conversion coating for the corrosion protection of aluminum

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.