The Effect of Three Kinds of Surface Treatment Methods on the Corrosion and Wear Resistance of AM60B Magnesium Alloy with La, Ce Addition.

Three kinds of surface treatments, including permanganate, molybdate, and phytic acid conversion films, were fabricated on La-Ce mischmetal containing AM60B magnesium alloy. Their effects on the corrosion and tribological behaviors of the alloy in 3.5 wt% NaCl solution were systematically investigated via Mott-Schottky analysis, electrochemical measurements, and friction-wear tests. The results show three surface treatments shift the flat band potential in the negative direction, reduce the corrosion current density, enlarge the electrochemical impedance arc radius, and decrease the friction coefficient, conferring remarkably enhanced corrosion and wear resistance to the alloy substrate. The performance enhancement is ascribed to the formation of uniform, dense conversion films that act as effective physical barriers, which impede the penetration of corrosive species, isolate the substrate from the aggressive aqueous environment, and improve the chemical and electrochemical stability of the alloy-solution interface. The comprehensive performance ranking of the three surface treatments in terms of corrosion and wear resistance is as follows: permanganate conversion film > molybdate conversion film > phytic acid conversion film.