Environmental Protection of Anodizing on AZ91D Magnesium Alloy

Abstract

We studied the environmentally friendly Anomag process of anodizing onto AZ91D magnesium alloy. This process uses mainly a phosphate solutions without the need for deleterious materials such as heavy metals or fluoride. We also investigated the characteristics of the coatings formed, such as their structure, composition, and corrosion resistance. X-ray diffraction analysis revealed that the anodizing coatings had an amorphous of glass-like structure. In salt spray tests, these coatings, which had an average thickness of 10 μm, retained their anticorrosive performance over 1000 hours. This excellent corrosion resistance is attributable to the dense transition layer present at the interface between the coating and the base material.