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Can you plate brass with Pt without a sub-plating?

2004

I have a component that is difficult to machine and doubly so because of the alloy being used. It needs to have a mirror like surface finish and most important: it needs to be non-magnetic. One of the possibilities that I am looking into is using a standard substrate of 70/30 brass (no lead) and plating it with platinum. The one question that keeps surfacing is can this part be "plated" directly without the use of a nickel substrate? Is there another substrate layer that can be used in lieu of nickel? And , one last question: can vacuum deposition be used successfully. The plating needs to be "hard", non-porous, highly conductive, and relatively thin.

The part is .050" dia and .125" long with a "vee" in one end. The "vee" is critical and must maintain its shape and surface finish. I am not a plating expert but I have done some searching for information including ASM materials and have not found anything useful.

Jim Moss
- Littleton, Massachusetts

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I believe you can plate Pt directly onto brass, assuming the proper cleaning and preparation steps are used. There will be some diffusion of Pt and brass at high temperatures, but should be ok for room or low temperature environments.

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

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First of two simultaneous responses --

Enter the Pt solution "hot", that is, make contact outside so that when the brass hits the Pt solution it immediately starts plating. Zinc and Copper are serious contaminants to a Pt solution. Better Gold Strike in a citrate type strike solution then the Pt solution will "see" gold which is insoluble. And your Pt solution will last a lot longer.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2004

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Second of two simultaneous responses -- 2004

Hi Jim, plating platinum over brass will depend on the type of plating chemistry you use. Many Pt baths use either a high or low ph and are not suitable for direct plating onto brass substrates. A variation of a "p" salt with a ph of 8 may work but I would still be inclined first to use a neutral gold pre-strike followed by platinum plating.

Vapor deposition can work assuming that you can achieve a thickness of at least .20 microns of platinum

Best Regards,

David Vinson
Metal Arts Specialties - Leonard, Michigan