The effect of surface pretreatment on the corrosion performance of Electroless E-coating coated AZ31

This paper presents an investigation on the effect of substrate pretreatment on the corrosion of Electroless E-coating coated AZ31 Mg alloy. Immersion, salt spray, cyclic exposure, AC electrochemical impedance spectroscopy (EIS). XPS analysis and XRD examination results show that the coating protection performance can be significantly improved if the substrate surface is properly dehydrated at a high temperature after wet-cleaning. A simple wet + dry process involving acid-etching + dehydration can be a practical surface preparation technique for the Electroless E-coating on Mg alloys in industry. A surface dehydration model is proposed to explain the coating formation and protection performance. (C) 2012 Elsevier Ltd. All rights reserved.