Tribological behavior of cathode plasma electrolytic deposited Al2Y4O9 coating on aluminum alloy

Abstract

Abstract Ceramic coatings are widely used as protective barriers on the surfaces of various metals and alloys. Herein, a novel surface ceramic treatment, i.e., cathode plasma electrolytic deposition (CPED), is proposed for the surface of an Aluminum (Al) alloy. The coating, prepared in an Y(NO3)3 aqueous solution on the surface of the Al alloy, consists of Al2Y4O9 as the major phase component, Y2O3 as a minor phase component, and amorphous Al2O3 in the grain boundaries. As the applied voltage and deposition time increased, the crystallization of the coatings was enhanced. When deposited at 130 V for 10 min, the contact angle of the ceramic coating reached 141.0 ± 2.6°, indicating an enhanced self-cleaning effect. The ceramic coating also exhibited excellent self-lubricating and anti-wear effects. The friction coefficient of the CPED-treated sample vs. ZrO2 ball or bearing steel ball decreased from 0.55–0.65 to 0.26–0.31 when the load was 3 N and the reciprocating velocity was 10 mm/s. Correspondingly, the wear rate of the CPED-treated sample vs. the ZrO2 ball or bearing steel ball was significantly reduced. Results indicated that CPED is effective for the formation of self-cleaning and anti-wear ceramic coatings on Al alloys.