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Pitting "Nickel material" for my pipe NiCr Plating

February 23, 2009

Dear Sirs,
I have pitting problem. The pit was determined using SEM EDX as nickel. The pipe supplier had already improved the anode's bag by using double filter (one is a feather filter that will shut whenever the anode is removed from the bath). But the pit still occur. What do you suggest ? Does the pre treatment (we have degreasing and acid activation before semi bright) will affect this matter? Does the unstable current will cause the unexpected nickel adhesion? The current is controlled at the main utility and do not describe the actual current that working inside the bath.

the supplier of pipe also use the air agitation and we would like to improve to eductor [on eBay or Amazon] agitation to avoid hydrogen trap as our SEM EDX analysis still continue. What do you think about the real advantages in using eductor ? cause now, our air agitation pressure is controlled at the main compressor distributed to 2 semi bright and one bright nickel bath.

Thank you very much for your kind attention.

Muhammad Edwin
Buyer - Jakarta, Indonesia

Hi, Muhammad. I don't think a SEM EDX is the right tool for the job because "you can't see the forest for the trees". Examine the pits with a low power jeweler's loupe instead. If they are shiny, hemispherical depressions they are hydrogen pits caused by hydrogen bubbles growing in that area. Air agitation or eductors can dislodge them, but it is important that the surface tension of the bath be carefully controlled. Improper cleaning can also cause hydrogen pits though.

Your nickel supplier should have a service person who can assist you.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 24, 2009

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March 10, 2009

Dear Muhammad,

Try to share my experience, most of the time I heard that peoples simply claimed "pitting" but normally it was not the case.
Sometimes roughness also they claimed as "pitting".

As you could detect with SEM that you can find the pitting as Nickel element, I presumed it was roughness of Nickel chip or salt that stick on the Nickel plated surface.

With doubling anode bag, increasing filter capacity and right installation of inlet and outlet of filter pump can eliminate or at least reduce this problem
Also the right way to add Nickel salt and Boric Acid during operation.

As I knew "pitting" has 2 categories,firstly is Hydrogen pitting as Ted has mentioned it, and secondly is oil pitting.

Hydrogen pitting you can help by lower the surface tension or wetting agent, and for oil pitting you have to clean the bath from the oil by carbon filter or carbon treatment and the same time you must stop introducing oil to the nickel bath/solution.

For pipe/tube material it is big chance to introduce oil into Nickel solution, not only that you can carry alot of oil from the first rinsing after degreaser until end of the processes if your degreaser could not remove the oils completely.

Using right and good quality degreaser and also eductor in degreaser (must use de-mulsifier or low foam degreaser) can help a lot to remove the oil from the tube/pipe from the beginning of the processes.

Eductor in Nickel plating tank also can give better performance but you need to know how to install it and must have enough quantity (eductor) in the tank and you need pressure to get better turbulence effect.
You could not use the outlet of filter pump to get the effect, you must install a separate pump for it with high pressure.
But normal air agitation also works well,but make sure that you have installed a good filter for the inlet of air in blower unit, to prevent dust introducing to the nickel tank and will cause roughness.

That's all that I can share with you, hope that you can rectify the problem soon.

Best regards,

Tony Chandra
electroplating practitioner- Jakarta, Indonesia

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March 14, 2009

Dear Muhammad,

I believe the pitting that you mentioned that you can detect by SEM EDX as Nickel was roughness.

Pitting is small hole that you could not feel it but roughness you can feel it by your nail (above layer).

Pitting has 2 type gas pitting and oil pitting.

Gas pitting caused by hydrogen gas that stick on the layer during plating, then you hardly can get nickel deposit.

Oil pitting also cause by oil sticking on the surface and could not get nickel deposit as well.

Try to source the cause of the pitting either "gas" or "oil"

Good luck.

Best regards,

Tony Chandra
electroplating chemicals - Jakarta, Jakarta Barat, Indonesia