Enhancing Dry Sliding Wear Resistance of Pure Mg by Plasma Electrolytic Oxidation Ceramic Coatings Using Silver Addition

Abstract

This study investigated the wear effect on ceramic coated Mg by Plasma Electrolytic Oxidation. Three series of PEO coatings were prepared; one of was the effect of silicate electrolyte (5, 8, and 10 g/L) concentrations and the other was the effect of coating time (5, 10, 15 min), last one was the effect of AgNO3 (0.1, 0.2, 0.4 g/l) additive. The coatings were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The mechanical properties were analyzed by microhardness and linear wear test. The unlubricated wear resistance was observed by linear ball-on-disc tribometer. With increasing the silicate concentration, the average pore size and porosity percentage and the surface roughness increase. On the other hand, with increasing the coating time, the surface morphology gradually becomes flat. The coating time caused more compact and homogenous appearance. The surfaces coated with the addition of silver were obtained smoother and denser. The wear resistance of the high time coated Mg was significantly improved. The best wear resistance was obtained with silver-reinforced coatings.