High temperature oxidation behavior of arc sprayed duplex aluminum bronze based coatings

The performance and effectiveness of arc-sprayed duplex coatings on mild steel was evaluated.The duplex coating structure is comprised of an inner aluminum bronze layer and an outer layer of aluminum 0.1-0.2 mm.Cyclical oxidation test,each lasting 12 hours,was performed in air at 900℃ for ten times.The results demonstrated that the coating had a better oxidation resistance than single aluminum bronze coating.The application of aluminum layer benefits the formation of a thick alumina-rich protective layer on coating surface and the sealing of the pores of coatings at elevated temperature.After one cyclical oxidation test,a continuous Al₂O₃ layer was formed along the interface coating/substrate,which did not make the coating adhesion degraded.The composite coatings provided steel substrate with a good high temperature protection.The composite coating would be a potential candidate for protecting steel substrate at high temperature.