Anodizing of Pure Magnesium in Sodium Hydroxide Electrolyte Solution

Abstract

Anodizing is an electrochemical process to produced anodic coatings for improving magnesium (Mg) properties such as corrosion-resistant. In this study, anodizing of pure magnesium in 1 M NaOH electrolyte for 1800 s and at 21 °C and different constant current or voltage was investigated. The effect of voltage and current on morphology and thickness of the resulting anodic layers was evaluated by scanning electron microscopy (SEM) equipped with EDX analyser. The thickness of the produced layers was determined to utilize digital image analysis. The results showed that using lower current of 0.08 A non-compact anodic layer was produced. When a higher current of 0.2 and 0.5 A was used compact and thicker anodic layers were produced compare to lower current of 0.08 A. The anodic layer produced at a constant voltage of 20 V was rougher, thicker and contained microcracks compare to anodic layers formed at constant voltage of 12 V and at constant current (0.2 and 0.5 A).