Adhesion Problem: Nickel over 316 SS
I am having difficulty with adhesion of nickel plating to a 316 stainless steel surface. Can someone please suggest a sequence for plating nickel from a sulfamate bath on 316 stainless steel. I run a plating shop specializing in hard chrome, however, I have one project which requires a heavy build up of nickel prior to the chrome plating. If this project is successful, it could very well mean an entire new avenue for my business. So far my every attempt has resulted in peeling. I have a good deal of experience with sulfamate baths, however, the application was electroforming where adhesion was a bad thing.
I currently have an electrocleaning tank, a woods strike, and a nickel sulfamate tank. The part is very large and I don't have additional tank capacity for acid dips or anything of that sort. I need to be able to prep the surface by hand application. Please tell me you have a solution for me!Barry Burnett
- Spartanburg, South Carolina
I would try low pH ( 2.5 ) and low current density. Can you get electroless or acid copper strike? Cyanide copper may also give adhesion you may need. Try submersion plating by pouring Copper sulphate/H2SO4 mix if you have no extra tank.Payal Mag
- Charlotte, North Carolina
You are going to find it very difficult without an acid dip. You will have slightly better luck if you can grit blast it with an appropriate grit size of aluminum oxide which any embedded grit will dissolve in the caustic tank. Next you could try an anodic-cathodic treatment in the Woods nickel if you have a large enough power supply. None of this will replace an appropriate acid etch.James Watts
- Navarre, Florida
You say that you have a Wood's nickel strike, but Mr. Watts insists in an acid dip, also Mr. Payal recommends a pH of 2.5. Probably I don't understand the situation. A Wood's bath is very acid (close to pH 0) and should be able to activate your 316 provided you use the appropriate sequence and amperage. If you think you've tried everything give the following a chance: Try a good cleaning and then strongly rub the part all over with abrasive pads of the type of Scotch-brite wet in a dilute HCl), then 5-10 minutes immersion in the Woods followed by a good starting kick of at least 40-50 A/sq ft (no reverse). Then resume normal amps for at least 7 min. This very long time I recommend for the strike will let you see should you have peeling, if the following sulfamate plate came off the 316 or off the strike (they have a slight different color). Finally, back to basics: make sure your baths (specially the Woods) do not contain copper, other metals or contaminants. If so, dummy!
Good luck and advise us about your results.Guillermo Marrufo
Monterrey, NL, Mexico
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