Gas pitting problem in Nickel plating

A. Hi Dave. It's possible to have too much air agitation, and we have several threads in the forum that discuss that situation. But you are probably using an aquarium bubbler with little likelihood of being too aggressive, and the immediate answer is that you can't let those accumulating hydrogen bubbles grow anyway. Agitation is one of the few weapons you have against them.

You probably need both a wetting agent and air agitation to dislodge those bubbles. However, I would not hang the part with a surface horizontal. I would tilt the parts in one or more planes so the bubbles have an angularly upward escape route they can follow. You should probably look at the pits with a jeweler's loupe and verify that the pits are shiny and hemispherical, as evidence that hydrogen gas is their cause.

Luck & Regards,

A. I assume that your bath is a watts standard bath in such case the pitting can be due to

Wrong wetting agent/lack of wetting agent
Low nickel content
Oil contamination
lack of cleaning in some cases

A. Dear Muhammad,

Pitting could be due to, but not limited, to the following reasons:
i) Gas (usually Hydrogen) bubbles
ii) Oil droplets
iii) Particles

Please send us some photographs as the shapes and appearance of the pits will give an indication as to what is causing the pitting.

Thanks,

Maurice.

A. Facing pitting problems should not only be considered as a "chemical" process issue. Most likely it could be caused either by air agitation (this information is missing from your side) as well as the whole electrolyte pumping circuit, check for possibilities of air in your electrolyte pump system. Also check your temperature and increase it in order reducing the surface tension to provide a better process related gas bubble escape.
I do expect that Anode-Cathode area, type of anodes in use as well as all other additives/chemicals are within range.

Happy New Year!

Cheers,
Dominik

A. I'm sorry I forgot to comment that lack of boric acid causes pitting and organic and inorganic contaminants too...

A. Hi Corey.

Unfortunately, it's not usually as easy as that. Larry Durney wrote a whole book.
just on how to correctly approach the troubleshooting of electroplating operations :-)

But if you have pitting, and holes, and hydrogen bubbles, probably the first thing to look at is your surfactant and surface tension. Please provide additional details when you can.

Regards,

A. First check your anti pit (wetting agent)
Second, add or increase your air agitation and insure that the bubbles sweep across the part.
Third, consider changing the angle of the parts in the tank so that the air will partially flow through the screen.

A. Sounds to me like you need to thoroughly check the solution analysis, specification and operating conditions. Gas pitting is normally caused by low surfactant levels and/or poor agitation. Nickel nodules are often caused by poor agitation, solutions contaminated with dust particles, too higher cathodic current density, etc. Both effects can be caused by incorrect pH.