Corrosion behavior and microstructure of micro arc ceramic coating formed on the 6061 aluminum alloy

In this study we investigated the effect of potassium hydroxide and sodium silicate concentration into micro arc oxidation electrolyte on the corrosion behavior and micro-structure of the ceramic coating formed on the 6061 Al alloy. The potentio-dynamic polarization was applied to investigation of corrosion behavior of micro arc oxidation coating in 3.5 wt.% NaCl. XRD analysis, SEM and EDX were used for studying and identification of coating morphology, micro-structure and chemical analysis, respectively. The potentio-dynamic polarization results showed that the corrosion behavior was improved by increasing of potassium hydroxide and sodium silicate concentration into coating electrolyte. The XRD pattern showed that oxide ceramics and inter metallic compounds have formed on the surface under micro arc oxidation process. SEM and EDX illustrated the increase in the concentration of potassium hydroxide and sodium silicate lead to a reduction in breakdown voltage which in turn improves the surface quality as decreased in micro-cracks and features.