ECONOMICAL NON-SPARKING ANODIZATION OF MG ALLOYS WITH HIGH CORROSION RESISTANCE

Innovative economically and environment friendly non sparking anodization of Mg alloy is characterized by low voltages and low energy consumption which lead to a great improvement in their corrosion behaviour. Low voltage, 2V-15V, was applied to investigate the behaviour of Mg-3%Zn-0.8Ca through electrochemical anodizing. The effect of this condition on the non-sparking discharge anodic film formation process as well as surface morphology and composition were studied. Field emission scanning electron microscopy (FESEM), Energy dispersion X-ray (EDX) and X-ray diffraction (XRD) were used in this study for the coat surface. The corrosion resistances of anodized Mg alloys in simulated body fluid (SBF) were characterized by potentiodynamic polarization and electrochemical impedance (EIS) techniques. The obtained results showed that that the corrosion resistance of anodized Mg alloy at low voltage was duplicated. Higher voltages of anodization causes horizontal and vertical expansion of lamellar structure resulted in the formation of multi cracked layer structure with high corrosion rate. The improved corrosion resistance of the anodized layer is mainly due to the formation of Mg(OH)2 phase