Letter 30017

Plating on magnesium  

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We are plating mag with nickel and we have the following questions.

1. Which nickel finish is the most durable?

2. What is the best thickness to produce a cosmetic and durable finish? The parts will be handled by doctors and the device is portable.

3. Are there cosmetic standards that we can call out on the drawing to insure quality parts. The parts will be manufactured in the US so any ASTM or US finishing type spec will work.

Thanks

Don P
medical equip - Mt. View, CA, USA

The most durable nickel finish will be a duplex electroless nickel plating. After alkaline cleaning, acid etching/pickling, and fluoride activation, apply ~ 8 micrometers of low-phosphorus nickel, followed by ~ 17 micrometers of either mid-P Ni (6-9% P) or high-P Ni (> 10%). This duplex coating results in a more durable, corrosion resistant finish. The fluoride activation can be replaced with a zinc immersion followed by a copper strike. The standard ASTM B480 [link is to spec at TechStreet] provides details on preparation of Mg alloys by either electroless (autocatalytic) Ni or Zn immersion + Cu strike. I will let others discuss the cosmetic standards issue.

Best of luck with your project.

Toby Padfield
Automotive module supplier - MI, USA

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