Anodizing Treatments for Magnesium Alloys and Their Effect on Corrosion Resistance in Various Environments

Abstract

This paper reviews various aspects of anodizing of magnesium alloys, such as the basics, processes, properties and applications. It systematically summarises the existing fundamental studies and technical developments of anodizing of magnesium alloys, and concludes that new anodizing processes based on electrolytic plasma anodizing that convert the surface of a magnesium alloy into a hard ceramic coating in an electrolytic bath using high energy electric discharges can offer improved wear and corrosion resistance. These new anodized coatings are often claimed to perform better than the traditional ones obtained through older anodizing processes, such as DOW17 or HAE. The new anodizing techniques are chromate free and hence environment friendly. It is expected that more cost‐effective, environment‐friendly and non‐toxic anodizing techniques will be developed and applied to magnesium alloy components in the future.

Sealing of PEO Coated AZ91 Magnesium Alloy Using La-Based Solutions

“…Instead, the sample treated at 40 ∘ C and 50 ∘ C for 30 was characterized by values of 4 higher than 3 , because the sealing layer provided a more corrosion resistance. The improvement in the corrosion performances after the PEO treatment is comparable with the one reported in literature regarding this kind of treatments performed on magnesium alloys [8]. In fact a remarkable increase in the corrosion properties can be obtained also without a post-treatment.…”

The effect of anodizing electrolyte composition on electrochemical properties of anodized magnesium

“…But it has increased the density and quality of the coating and consequently increased corrosion resistance. In the present study, as in other studies (Wu et al, 2007b;Chai et al, 2008;Asoh and Ono, 2003;Mizutani et al, 2003;Blawert et al, 2006;El Mahallawy et al, 2011;Lin and Fu, 2006), it should be said that changes in the composition and type of solution used for anodizing have caused a change in the corrosion resistance of the coating layer. Hsiao et al investigated the effect of adding Y and G on the anodizing solution for alloy AZ91 and observed that it caused major changes in the coating film and its corrosion resistance .…”

SRET Evaluation of the Corrosion Behavior of Thixocast AZ91 Magnesium Alloy in Dilute NaCl Solution at Room Temperature

“…Comparison of local anode current of AZ91-TC and AZ91-DC alloys. In a previous work, the corrosion behavior of AZ91-DC alloy was investigated in the same solution (0.014 M NaCl) using SRET method (18). Comparing those results with the results of this work, it is noticed that AZ91-DC alloy has higher QEMF values than AZ91-TC alloy; the maximum local anode currents are higher too.…”