Study of Nanostructured CeO<inf>2</inf> Coatings on Superalloy

Nanostructured CeO2 coatings on Superni-718 substrate were deposited by electroless process in the present work. Microstructure and cyclic high-temperature oxidation behaviour of nanostructured CeO2 coatings on Superni-718 substrate was investigated. Cyclic high-temperature oxidation tests were conducted on uncoated and coated samples at peak temperatures of 900°C for up to 50 thermal cycles between the peak and room temperature. The results showed that the coated sample has higher oxidation resistance as compared to bare substrate at 900°C. The external scale of the coated sample exhibited good spallation resistance during cyclic oxidation testing at both temperatures. The improvement in oxide scale spallation resistance is believed to be related to the fine-grained structure of the coating. The oxidation results have shown the improved oxidation resistance of the CeO2 coating on superalloy as compared to bare substrate up to 50 cycles. The relevant oxidation mechanisms are discussed.