Mechanism of the formation of stannate and cerium conversion coatings on AZ91D magnesium alloys
Journal
Applied Surface Science
Journal Volume
276
Pages
578-585
Date Issued
2013
Author(s)
Abstract
The characteristics of the formation of conversion coatings on an AZ91D Mg alloy were detailed. Because the galvanic effect prevailed around the eutectic α + β, alkaline stannate conversion coatings nucleated first near the β phase where plenty Mg 2+ were present. Conversely, the formation of cerium conversion coatings largely relied on an increase in the interfacial pH. Intense dissolution of the primary α phase in acid cerium nitrate solution caused hydrogen bubble evolution, which, in turn, resulted in blisters. It is evident that the galvanic corrosion routes on the AZ91D depend on the pH of the conversion coating solution. © 2013 Elsevier B.V. All rights reserved.
Type
journal article