An Investigation of Pulse Anodization Duty Ratio and Sealing Treatment on the Corrosion Behavior of the Anodic Coating Layer in Magnesium AZ31B

In this work, we describe the effect of pulse anodizing duty ratio on the corrosion resistance of anodicfilms in magnesium AZ31B. The process involves the application of square pulse potential for a constantperiod with a duty ratio varying from 40, 60 and 80%. In several samples, a sealing treatment for 30 min utes was conducted after anodization in order to seal the pores available in the anodic layer. After anod izing, the surface morphology of the anodic layer was examined using a scanning electron microscope(SEM Hitachi SU3500). The corrosion characteristics of the sample were evaluated through an open cir cuit potential (OCP) and potentiodynamic polarization test using potentiogalvanostat. SEM observationshows that the increase of anodization duty ratio (α) results in a more uniform anodic layer, with fewerpores and cracks. The increase of duty ratio (α) decreases the OCP value from approximately -1.475 toabout -1.6 Volt, and significantly improves the corrosion resistance of the anodic coating by 68%. Thecombination of anodization and sealing treatment produces an anodic coating with a very low corrosionrate of 4.4 mpy. KCI Citation Count: 0