Pitting / frosty pitting issue on Gold Plating for small parts

[tdomm]

We are getting a frosty / hazy gold plating on some 303 Stainless steel parts. (the parts look pitted upon 50X power inspection) The parts are passivated using Citric Acid prior to gold plating per ASTM A967-05 They then get a Sulfamate Nickel Strike and then a gold strike of 99.5 pure gold per AMS 2422D. This condition happens only occasionally. The parts are only .030 Dia.


Does anyone have ideas of what would cause this issue?

Thanks

Tdomm

 

[tomwalz]

I always start with cleanliness.

Check process parameters. The folks in the finishing forums seem to focus on pH.

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[EdStainless]

Have you done detailed inspection of the parts after Ni strike?
My guess is that you are not getting a smooth layer of Ni.
Like Tom said, cleanliness.........

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P.E. Metallurgy, Plymouth Tube