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Brown film on S-pellets in Nickel Sulphamate Cell

October 26, 2011

Dear All,

We are facing a problem with our Nickel Sulphamate Electroforming cell.
After 2-3 days of full operation our pH was increased to 4.3 (our spec is 4) so we add some sulfamic acid [on eBay or Amazon] to decrease the pH. We decreased pH to normal levels (3.95) and we started plating on this cell. After 5-6 parts we removed the anode basket to wash the s-pellets and we saw that 90% of the pellets was coated with a brown film (first time we've ever seen this after 2 years of running the cell). The parts made were OK but we cannot get rid of this brown film on s-pellets (washed and soaked with sulphamic acid).
Any help would be much appreciated.

Regards, Dimitris.

Dimitris Angelakos
Production Enginner - Tripolis, Greece

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October 30, 2011

I think we could do with more information. Firstly what are you electroplating? If it is brass of copper, you could have an immersion coating of copper on your anodes. Secondly, have you checked to your own satisfaction that you are really using S-nickel?
Thirdly, what is your bath composition -do you use chloride or other halide additive?

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK