Serious Education ... plus the most fun you can have in metal finishing.
Contamination on Nickel Plated Surface
Contamination of Nickel Surface was found on nickel plated product with copper substrate.
The contamination on the surface is somewhat brown in colour on the nickel surface, look like copper oxide. But about 30 microinch of nickel was plated on the copper surface, do copper oxidizied after nickel plated on it.
The contamination comes out not immediately after the plating process but after some days. It is difficult for us to figure out the cause.Ken Shuen
First of two simultaneous responses--(1999)
What you describe sounds very much like a bath with a very high copper contamination, especially if it is worst in the lowest current density areas.
A very long low current density dummy with agitation may lower the copper content enough to become usable. You might want to try this recovery "off line" .
If the cause is not from parts dropped into the tank, you may have to start going in and coming out "hot".
Copper contamination does not show until it hits a critical level and then a tiny tiny increase makes it go bad to terrible rapidly. The bulk of the contamination could have been from a single small part that was lost months ago.James Watts
- Navarre, Florida
Second of two simultaneous responses--(1999)
Hi Ken ,
I am not sure I understand your problem , but Nickel will gradually over time develop a "Golden cast" over the entire surface , rather than remain silvery white as plated . there is nothing you can do that will stop this process it is simply an oxide forming on the surface of the nickel it is natural . If your problem on the other hand is a spotting problem , in other words , small patches appear over the surface much as the spots that appear on a child's skin when they get measles then the problem is porosity in one or both coatings , and the cure for this could be as simple as a heavy Activated carbon treatment for the nickel bath , or it may involve more complicated treatments with Permangenate , Hydrogen Peroxide and/or other oxidants "etc"
- Victoria Australia
You don't mention what type of Nickel process.
Is it a Bright, Watts, or Duplex? Considering that the brown staining is developing after several days tends to point to an outside source. We have experienced that Bright Nickel coated parts when packaged with recycled new print material, will cause brown staining after several days, especially in a humid environment. This type of paper contains sulfides which will react with the coating. If your using this type of packaging material check with your supplier. Good Luck.Juan Ocampo
plating shop - San Jose, California
I think you problem on Ni-plated copper substrate is porosity of Ni-coating. May be that is organic contamination of your Ni-bath or you need to increase of corrosion protection by using two layers of Ni: he first-2- 3 micron of Ni without organic additives and the second up to needed thickness from your Ni-bath. Ninan.Sezin