Effects of graphene additive on microstructure and properties of MAO ceramic coatings formed on AA7050

Graphene-containing ceramic coatings were prepared on the surface of 7050 aluminum alloy (AA7050) by micro-arc oxidation (MAO) technology in a silicate electrolyte added graphene with different concentrations. To analyze the surface morphology, roughness, phase composition and distribution of elements, bonding force, hardness and corrosion resistance, the scanning electron microscopy (SEM), x-ray diffraction (XRD), x-ray photoelectron spectrometer (XPS), automatic scratch instrument for coating adhesion, micro hardness tester, electrochemical workstation were used, respectively. It is showed that the micro-pore size of the MAO ceramic coatings which mainly consisted of Al2O3 decreases and the compactness obviously improved with the addition of graphene. In addition, the roughness was the lowest (857.835 nm), the hardness was the highest (1651.88 HV) and the adhesion was the best (46 N) as well as the corrosion resistance had been significantly improved when the concentration of graphene was 10 g L-1.