46056

Cycle of problems in sulphamate nickel plating of Nickel Silver 770 alloy  

August 1, 2007

I am plating 770 Nickel Silver continuously with Bright Nickel Sulfamate. At first the material was coming out with a very dull whitish appearance. We consulted our vendor and he analyzed the solution, and through the use of the hull cell, gave us some recommended aditive additions. Still the material did not look great, only about 30% better. We decided after some investigation that the cleaner was a little on the old side, and changed it. This made the big difference, and this produced cosmetically acceptable material, however, now the material peeled. We went to an HCL pickle with electro activation and this made the plating stick but caused the cosmetics to revert to unacceptable. Somebody please help.

Mike Berrier
Process Manager - Addison, IL, USA

You are making silver chloride and leaving behind an ugly surface.

Instead, dip in 5%/vol Sulfuric Acid and then activate with cathodic cyanide. Make up a solution of 12 oz/gal Sodium or Potassium Cyanide plus 2 oz/gal nickel carbonate. Make the work cathodic using stainless steel anodes, use about 6 volts, room temperature, rinse quickly and go LIVE into a nickel chloride strike or a nickel sulfamate strike.

Robert H Probert Robert H Probert Technical Services Garner, NC, USA Editor's note:        Mr. Probert is the    author of Aluminum How-To

I would rinse the cyanide solution off before going into the acid tank. It may have been implied, but not said.

James Watts
- Navarre, Florida

Unfortunately, adding a Cyanide based chemistry is not possible, as we are a cyanide free shop. Also, a little more information, this is reel to reel plating, and we have discovered that when we lay down a thicker layer of Woods Nickel the Bright nickel is looking a whole lot better. Is there some type of reaction taking place between the Copper and the Zink in the 770 base with the Nickel?

Mike Berrier
- Addison IL USA

Correct me if I'm wrong, but I don't believe "Nickel silver", or "German silver" has any silver in it. It's a trivial name for nickel/copper/zinc alloys of various compositions.

It sounds like you are on the right track - you need more Hull Cell work and brightener tweaking. I strongly suggest that you do your own, or, hire a contractor to come in and do it on site for you. Do be advised, though, that as you increase brightness, you also are liable to increase deposit stress, the lack of which is the usual reason for using a sulfamate nickel as opposed to a Watts.

You could try a Wood's strike, preplate.

Dave Wichern - Bronx, NY, USA

The process that I have finaly begun to use is as follows: 1st pass: Electro Clean, pickle soak, Wood's Nickel strike. I have to run this first pass quite slow to ensure coverage of the Woods. 2nd pass: Cleaner Soak, electro-pickle of 10% HCL, Nickel plate. This is also running very slow and requiring a high thickness to avoid the very sketchy appearence. At a low speed and a high thickness the material looks excellent. As of right now this will be satisfactory to provide material to the customer, however, moving forward I need to provide a better process. I am already in the process of planning to move a Woods Nickel Strike in front of my Nickel tanks to avoid the two pass set-up, but is there any other information as to why it is that the material, which looks fine going into the line, for some reason, is coming out so poor looking without jumping through hoops? All other material produced on this line looks great. Thank you all for your help.

Michael Berrier
- Addison, IL, USA