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Magnesium better coating than zinc?

We are in the Fastener business to non-industrial customers. We supply fasteners to the decking industry and with the new copper laden treated lumber there is a need for better corrosion resistance. I am investigating if Magnesium coating would provide a better coating than the ordinary Hot Dip Galvanization process. Even the Zinc is not going to stand up against the copper in the treated lumber. I know that Mg is less noble than Zn, but is the MgO more corrosive resistant than Zn.

Thanks,

JOHN VERGUNST
FASTENER DISTRIBUTOR - KALAMAZOO, MICHIGAN, USA
2004

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I would use aluminum deposited by ion vapor deposition (IVD). It's a common coating, commercially available, and used extensively by the military as a cadmium replacement so there are MIL specs and tons of supporting data. There are many companies that provide the service, some listed on this web page.

Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover - San Diego,
California
2004

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Can you expand on that, Jim? As I understand it, the new pressure treated lumber uses copper additives and they cause galvanic corrosion of any non-noble metals. I would have expected aluminum to have the problem too.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004

John,

I will suggest Zinc Nickel alloy plating with 12 percent Nickel balance zinc , chromated to a nice blue bright or a black finish depending on need . The only other finish that could work may be a solder finish containing 60 percent lead , balance tin.

Regards,

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016
2004

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Aluminum, zinc, and cadmium are active metals that oxidize faster than ferrous or cupric alloys. In addition, their oxides are more tenacious -- they stick better to the base metal. If coat steel with pure aluminum, the aluminum will oxidize rather than the steel, but the oxide formed won't readily come off the surface. Hence, the corrosion rate is greatly reduced. There are additional, and very significant, improvements that can be obtained by applying a conversion coating atop cadmium or IVD aluminum coatings.

Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover - San Diego,
California
2004