A simple approach to fabricate protective coatings on the surface of AZ91 alloy and its corrosion resistance

Abstract

In this paper, the corrosion resistant coatings were fabricated on AZ91 Mg alloy by steam treatment using deionized water as a steam source. The treatment temperature was maintained at 150 ℃, while the treatment time was varied at 3, 6 and 9 h. The results showed that relatively dense steam coating can be formed on the surface of AZ91 alloy by steam treatment for 3-9 h, and the phase structure of steam coating was mainly composed of Mg(OH)2 and contained AlO(OH) and Mg-Al LDH. With the extension of the steam treatment time, the better the corrosion resistance of the steam coating, and the corrosion current density was as low as 10-7~10-8 A·cm-2, which was 3-4 orders of magnitude lower than AZ91 Mg alloy substrate (~10-4 A·cm-2).