Microarc oxidation coating formed on SiCw/AZ91 magnesium matrix composite and its corrosion resistance

A ceramic coating was synthesized on the surface of SiCw/AZ91 magnesium matrix composite by means of microarc oxidation (MAO) technique. Scanning electron microscope (SEM) was employed to characterize the surface morphology and cross-section microstructure of the coating. The phase structure and the chemical composition of the ceramic coating were analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the coating was evaluated by immersion test and electrochemical method. The results showed that the corrosion rate of the coated SiCw/AZ91 composite was decreased greatly compared with that of the bare composite because of the protective microarc oxidation coating.