Surface Anodic Oxidation of AZ80 Mg-Alloy in CTAB-Added Alkaline Silicate Solution

The surfaces of AZ80 Mg-alloy,an important high-tech material,were modified by anodic oxidation in the alkaline silicate solution mixed with 2 g/L cetyltrimethylammonium bromide(CTAB).The microstructures and corrosion resistance of the coating were characterized with X-ray diffraction,scanning electron microscopy and electrochemical workstation.The results show that the CTAB-addition matters.For instance,the CTAB-addition decreased the surface porosity by 50%,improved the compactness by reducing the density and size of micro-pores,increased the thickness of oxides coatings,induced formation of quite a few compounds including C₄H₆MgO₄,MgO,and Mg₂SiO₄,and significantly enhanced the corrosion resistance,because CTAB accounted for the much higher self-corrosion potential of the anodic oxides coating.Possible mechanisms responsible for the impact of CTAB-doping on the synthesis,oxidation and corrosion resistance of the oxide coatings were tentatively discussed in a thought provoking way.