Sm-doped MAO coating's formation and anti-corrosion on TC11 alloy

Focusing on clarifying the role of Sm-doping in regulating the micro-arc oxidation (MAO) coating formation process on TC11 Ti alloy and enhancing its anti-corrosion performance, the present work conducts a series of systematic experiments. SmCl 3 was used as the Sm 3 + source, and MAO treatment was performed on the alloy in an electrolyte of sodium phosphate. The coatings’ characteristics during their formation, such as surface topography and phase composition, the cross-sectional morphology, and corrosion resistance, were featured by SEM, EDS, XPS, XRD, and an electrochemical workstation. Discoveries suggest that the MAO voltage of the Sm-containing coating exhibited a tendency of initial decrease followed by a subsequent increase, and the coating-forming process of the coating was related to the voltage variation during the oxidation process. Rare-earth Sm-doping not only improved the coating's micro-structure but also contributed to an increase in coating thickness; meanwhile, phase composition analysis revealed the presence of Ti, anatase, rutile, and Sm 2 O 3 . Relative to the TC11 substrate, the Sm-containing coating showed a 54.81% reduction in the Icorr value and also a 53.88% decrease in corrosion rate. Electrochemical impedance measurement indicated that rare-earth Sm-doping could significantly improve the Cl − anti-corrosion performance of the TC11 alloy.