Corrosion Behavior of Anodized AZ91D Magnesium Alloy

Abstract

Abstract The effect of anodization on the corrosion behavior of die-casted AZ91D Mg alloy in aqueous solution was studied. Anodization was performed in 3 M KOH + 0.21 M Na3PO4 + 0.6 M KF base electrolyte with and without Al(NO3)3 addition. The anodized film was characterized by using x-ray diffraction (XRD), scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). The corrosion resistance of the various anodized alloys was then evaluated in 3.5 wt% NaCl solution using electrochemical impedance spectroscopy (EIS). The results showed that the anodized film was mainly composed of MgO, and the film properties were dependent on the condition of anodization process. Electrochemical testing results showed that AZ91D Mg alloy exhibited satisfactory corrosion resistance when anodized in the base electrolyte with 0.15 M Al(NO3)3 addition.