Thread 288/64

AZ91D magnesium surface resistance

We have produced a magnesium AZ91D prototype part for an electronics application. Our customer is finding the surface resistance to be greater than 1E9 ohms and would like a coating that will reduce this to between 1E5 and 1E9 ohms. The coating needs to be relatively thin (<.0015"). Would anodizing work for this? Any suggestions?

Thank you,

Tom Pastirik
magnesium coating - Calgary, Alberta, Canada
2004
publicly reply to Tom Pastirik

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There is a company in Ohio that has an "anodizing" process specifically for Magnesium parts called Luke Engineering & Mfg. Co., Inc [a finishing.com supporting advertiser] . I do not believe a traditional anodizing process will work on magnesium, but if you contact Luke, I am pretty sure they can recommend the most appropriate finish for what you have. The people at Luke really know metal finishing. If it is not something they can help you with (and I am pretty sure they can), I would guess they would know what direction to point you in. Good luck.

Richard Tucker
metal finishing - Henrietta, New York
2004
publicly reply to Richard Tucker

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Tom,

What is the current surface that produces such a high resistivity? Just the die-cast surface with entrapped lubricant, etc.? Some type of chromate? Have you discussed this with Hydro?

Toby Padfield
Automotive module supplier - Michigan
2004
publicly reply to Toby Padfield

An anodized coating of this thickness would only further increase the electrical resistance. You need to strip off the existing coating and apply a permanganate based conversion coating.

Jonathan Flicher
- Chicago, Illinois
2004
publicly reply to Jonathan Flicher

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Iridite chromate conversion coating will not only protect the surface from corrosion, but is easy to break through for low contact resistance. sold by Macdermid

Don Baudrand
Consultant - Poulsbo, Washington
(Don is co-author of "Plating on Plastics" [on Amazon or AbeBooks affil links]
           and "Plating ABS Plastics" [on Amazon or eBay or AbeBooks affil links])
2004
publicly reply to Don Baudrand

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The best solution is a ceramic layer.

Regards,

Henk Broeksteeg
supplier of pretreatment systems - Uden, Netherlands
2004
publicly reply to Henk Broeksteeg