Barb

Topic: Pitting in Hard Nickel Solution

We have been plating in a sulfamate solution designed to give a hard nickel product. We have a pitting problem that we cannot seem to solve. The surface tension is where it is supposed to be for this solution as are all of the parameters.  We tend to get the really bad pitting when we plate 1.5 mils. The pits don't really show up for thicker jobs.  The boric is at a good level, the pH is good, and I just increased the nickel chloride to see if that would improve the anode efficiency. Does anyone know of any other causes of hydrogen pitting or any other kind of pitting? And does anyone know how long it takes for a higher concentration of nickel chloride to affect the anodes?  Thank you for your help!

jimtrottier

Re: Pitting in Hard Nickel Solution

Hi Barb:

    There are a lot of times the numbers are right and something is drastickly wrong.  Have you looked at your parts under a microscope before they go into the nickel to see if the pits are present?  How is your adjitation?  Is it enough to expel the bubbles from the surface of your parts?  I would suggest you run a hull cell and see if the pits are there, if they are I would try and add some boric to see if it clears it up.sometimes running your boric a little on the high side can help.

       Jim 

DustinGebhardt

Re: Pitting in Hard Nickel Solution

You may also want to increase your wetting agent.  The surface tension may read in the normal range, but still be insufficient.  You can also talk to your chemical supplier to see if they have a different surfactant.  Some work better in different conditions.  You may also want to mix 2 (or more) chemicals. 

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

Barb

Re: Pitting in Hard Nickel Solution

Thank you for your responses. I talked to the engineer and he says that they have looked at the job before plating. I worry about overadding boric because I know that it can get to a point where there is oversaturation and that can cause pitting. The tank runs at around 140 degrees and the boric conc. is set for 45-48 g/L. I have run a hull cell and don't see any pitting. That is why my concern is the thinness of the jobs.

I added some more wetting agent yesterday and hopefully a test panel will be run today. We have discovered that with this wetting agent we can add and add and it gets to a point where the surface tension no longer decreases. Hopefully this addition will work. When you say to mix 2 or more chemicals, are you talking about 2 different wetting agents?

Thanks again for your help!

DustinGebhardt

Re: Pitting in Hard Nickel Solution

Yes, when I say mix 2 different chemicals I am referring to 2 different wetting agents.  Different surfactants affect the surface tension differently (or not at all, as the case may be).

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