JASON

Topic: hard chrome plating over nickel

We are a hard chrome plating shop that has been plating over all types of materials. For the first time we have been asked by a customer to hard chrome over an allready nickel plated shaft. how should we treat this? Reverse etch? Sweep current up slowly? Go right to plating amperage? This is something we have never done in 25 years of business and are willing to try.

DustinGebhardt

Re: hard chrome plating over nickel

The problem with plating over an existing nickel surface is activating the nickel enough so that the next layer is adherent.  Make sure that the part is clean and free from any oil, dirt, grease, etc.  I'd then try the reverse current etch and see how that works.  If it works, go ahead with it.  If you get peeling of the chrome, then you need to further activate the nickel.  A reverse current (cathodic) acid salt (with fluoride) can work well.  But be warned that I've never had 100% success doing this, although I typically am plating decorative chrome over nickel.

-Dustin Gebhardt,
CEF
Plating Engineer
Danaher Tool Group
Gastonia, NC

JASON

Re: hard chrome plating over nickel

Thanks Dustin,

We cleaned the part 100%. I was also recomended to put the part into the plating tank active (about 1.5 volts). We then ramped current up slow to desired amperage. We did over plate the shaft a little in case. Shaft came out perfect. Polished to size and seemed to adhere fine.