Effects of Current Frequency on the Microstructure and Wear Resistance of Ceramic Coatings Embedded with SiC Nano-particles Produced by Micro-arc Oxidation on AZ91D Magnesium Alloy

Abstract

To improve the surface wear resistance of the ceramic coating fabricated by micro-arc oxidation (MAO) on AZ91D magnesium alloy, ceramic coatings embedded with SiC nano-particles at different current frequency (500 Hz, 700 Hz, and 900 Hz) were produced during the MAO process. The morphology and phase composition of the coatings were investigated by scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), and X-ray diffraction (XRD). The surface roughness of the coatings was characterized by confocal laser scanning microscopy (CLSM). Simultaneously, the tribological properties of the composite coatings were evaluated by using a universal materials tester (UMT). The results shows that the wear resistance of the ceramic coatings with SiC nano-particles was improved significantly compared to the ceramic coatings without SiC nano-particles. Furthermore, the composite coating formed at current frequency 900 Hz showed the better wear resistance than the others.