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topic 3161

Corrosion in gold plated stainless steel


(1999)

We are plating gold on stainless steel(304 and 316 grade). The products are activated by woods nickel strike. We are facing problems with the gold plated product. The surface gets corroded. Is the problem related to the nickel chloride in the nickel strike? We use 240 gms/litre nickel chloride and 130 ml/litre HCl. Is there any other way of activating the stainless steel for gold plating.

ARUN
- new delhi, India



Hi Arun.

I don't know for sure from here, but if the Wood's nickel strike is corroding the stainless steel I think the likelihood is far greater that you are doing something wrong than the likelihood that Wood's nickel is an inappropriate treatment.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(1999)

I think the problem is related to

1. the (less-precious) nickel intermediate layer on the (precious) stainless steel,

2. to the chloride containing woods nickel strike which leads to pinhole corrosion and

3. to the final gold layer which is not pore-free.

For better corrosion resistance you should omit the nickel layer and plate the gold directly on the stainless steel. This can be performed with good adhesion by a strong acidic gold bath.

Uwe Manz
electroplating shop - Germany


July 11, 2012

Wood's Nickel strike is surprisingly hard to acquire in the UK in small amounts, and I only need a litre or so for a project I'm working on, so I was hoping to make my own. Nickel Chloride Hexahydrate is cheap and plentiful, but normally HCl is sold in the drug stores as a 36% by volume solution.(10 mol/dm3?) Someone on this forum said that an effective solution of Wood's Strike can be obtained by mixing 622 g/L NiCl2.6H2O with 233 g/L HCl. I make this around 2.5 moles/litre NiCl2.6H2O and just over 6 Moles/Litre HCl. Can I therefore use 2/3 litre of 36% HCl, Mix in 620 g NiCl2, and make the solution up to the 1 Litre mark, or is my math all askew? (I never was much good at calculations).

David Latham
- Derby, Derbyshire United Kingdom



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