The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Treatment for magnesium exterior parts

My name is Roberto Bazal, I've just started to work in a company and I'm looking for a superficial treatment for exterior parts of magnesium. At present,we make part of aluminium but we're very interesting in magnesium because of its excellent features. Is there any treatment for the magnesium for exterior part which can bear the corrosion? We specified a treatment that resist 1000 hours in a salt fog. Thanks in advance, Roberto Bazal Pérez.

Roberto Bazal Pérez
- Valladolid, Valladolid, Spain
2003

---

I'm not sure if this answers your question or is "cheating", but plating the parts with electroless nickel should get you the corrosion resistance you seek.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

---

There is a helicopter transmission housing application where a magnesium sand casting required extensive corrosion protection. The highest performance was obtained by first anodizing the parts, then sealing the anodic coating with 3 layers of baked epoxy, then priming with a layer of epoxy polyamide, and then topcoat painting with a polyurethane. This produced outstanding corrosion protection after 1000 hours of salt spray testing. You can read more in a technical paper authored by J. H. Hawkins (McDonnel-Douglass, now called Boeing) that appears on the Tagnite website (anodizing supplier). You will need to develop a requirement for how to evaluate the corrosion after 1000 hour salt spray exposure. ASTM D1654 was used in the above mentioned paper.

Toby Padfield
- Tory, Michigan
2003

You will need to chromate your parts and follow this with a coating of polyurethane or chromate epoxy primer and enamel.

John Hetherington
- Montreal, Canada
2003