A Composite Anodic Coating Containing Graphene on AZ31 Magnesium Alloy

Graphene was added to the electrolyte during the preparation of an anodic oxidation coating on an AZ31 magnesium alloy, and the effects of graphene on the surface morphology, chemical composition and phase composition of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of the coatings was evaluated via electrochemical measurements, including dynamic polarization curves and electrochemical impendence spectroscopy (EIS). The results indicated that graphene was successfully incorporated into the anodic oxidation coating, and the number of micro-pores and cracks on the coating dramatically decreased. Moreover, the electrochemical measurements demonstrated that the corrosion resistance of the coating improved because the corrosion potential increased 470 mV and the corrosion current density decreased approximately three orders of magnitude when 0.5 g L-1 of graphene was added to the electrolyte.