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Magnesium Alloy Plating

Our company is producing parts made of Magnesium alloys. We received an order to produce Magnesium Alloy plates with holes drilled in it, which are used for cooling liquid named Glycol mixed with water 41-60%. We need information, standards or procedures defining the plating needed to protect the Magnesium alloy against corrosion to the level that Aluminum alloys would be protected in the same configuration.

Thank you in advance,

Menahem Tadmor
- Rehovot, Israel
2002

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The question about corrosion resistance of Mg alloys and their protection by plating and/or surface treatment is very complex. Mg alloys are not an easy material to deal with if you have corrosion problems. Trying to summarize a very complex matter in a few lines, let's say that there are two approaches to maximize corrosion resistance. One is to use "high purity" alloys without treatments, the other is to use one of the several anodization treatments developed for the aeronautics industry. "High Purity" Mg alloys are said to be more resistant to corrosion than Al ones, but this is not always true, other factors may play a role, e.g. the microstructure, so you can't take for granted that high purity solves all problems. Anodization treatments work well, but you also have to be very careful since a scratch may be the start of a disastrous runaway corrosion. As far as I know there are no standard for corrosion specific to Mg alloys. Whatever you do, a solution for your problem probably exists, but it is likely that you'll have to find it by experimental tests.

Good Luck!

Ugo Bardi
Università di Firenze - Florenxe, Italy
2002

Well, we treated this part. Forget about anodizing, the coating should be conductive. It was treated by special non-metallic conductive coating for magnesium. The part is now in field test for one year.

Ilya Ostrovsky
Surface Treatment - Germany/Israel
2004