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  for Metal Finishing since 1989
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Magnesium corrosion protection

2001

I am developing a new housing and covers using a AZ91d mag casting. I will be using steel hardware to secure these together. The mag parts are finish with DOW20 under a powder coat(where these parts mate, there is no paint for emi issues).

Am I going in the right direction, with this type of protection?

I am also thinking about having the hardware zinc plated.

Carlos Santos
- Lowell, Massachusetts

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Zinc plating the hardware is a good idea as there is the issue of bi-metallic corrosion between the dissimilar metals. If bare steel bolts are screwed into the magnesium they will corrode together and be almost impossible to remove.

Martin Trigg-Hogarth
surface treatment shop - Stroud, Glos, England
2001

If this is for an outdoor application...I would suggest you run painted sample plates of your material in a salt chamber prior to introducing any other components. You will get a feel for the reactivity of az91d by itself, as it will be 10 times worse with other materials...especially a conductive gasket with Silver or Nickel. Dual gasket approach will be your best option if shielding is necessary.

James Hale
- Arlington Heights, Illinois, USA
2001