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"Nodules in Nickel Plating"



 

I am currently experiencing a nodule problem with our Nickel plating process - Watts type formulation. Chemical balances are in order with appropriate filtration, electrolytic purification and Carbon treating. pH is maintained @ 3.8. I am convinced it it not a particulate contamination problem being dragged into the bath. Chemical analysis has revealed no detectable limits for Cu, Fe, Mg, P, and Zn. However, there are 150 mg/l of Ca and 4900 mg/l of Na. We currently soften the water used for make up lost due to evaporation. Has anyone else experienced a similar situation.

Stanley A. Watson
- Marlborough, Massachusetts
^


 

May I know temperature used? Have you checked contaminations of Chrome? Do you have a hole in anode cloth/bag? What current density are you using? How is hull cell? What is chloride level used by you? Do you see Nickel particles in bath at ends?

Payal Mag
- Charlotte, North Carolina
^


 

Bath temperature is 155 F, there is no Cr present, the anode bags are double (two separate bags over one another). The current density is 55ASF and the Hull cell test looks great, bright finish over the entire current density range. The bath is a high chloride concentration in the 15 oz/gal range.

Stanley A. Watson
- Marlborough, Massachusetts
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With data given, it looks like leak in filtration. You can take bath solution in Lab and filter using 0.45 micron filters under vacuum. Observe particles on paper.

Payal Mag
- Charlotte
^


 

It could well be that your problem is calcium contamination. Calcium (as calcium sulfate) has a reverse solubility, that is, it is less soluble at high temperatures than at low temperatures. Calcium generally precipitates from the solution as needles but, depending on the operating conditions, can also precipitate as granules. The concentration quoted, 150 mg/L is close to the solubility point at 155F. If at all possible, lower the temperature to 140-145F and see if the problem goes away. If it does then it will be necessary to remove the calcium by batch treatment in a separate tank. The best material to use is sodium bifluoride. It must be added in amounts less than the stoichiometric amount. An excess of fluoride is dangerous and may result in the attack of titanium anode baskes, if used. The fluoride treatment also removes magnesium. Therefore, it will be necessary to analyze the solution for both Ca and Mg just prior to the treatment. The plating tank must be thoroughly cleansed since there may be residual Ca salts on the tank walls and anodes.

Lou Gianelos
Retired - Eastlake, Ohio
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Calcium will causes small pimples but not really "nodules". Low pH favors noduling, so raise the pH to about 4.1 or maybe 4.2. Squiring agitation causes nodules, so be sure the agitation is a moderate movement and not squiring on the spot that is noduling. As stated in all of the above, any contamination contributes to noduling, pH and agitation just exagerate the formation.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina
probertbanner
^



May 16, 2012

Q. Hello

I plate nickel and chrome on steel (musical instrument). But after nickel plating, I can see many small nodules on the component. My process is soak clean + Electroclean (alkaline)+ Acid dip (Acid salt) + Watts nickel (with GL-1 additivefrom ATOTECH) + Bright Nickel + Chrome.

I don't know that the process mentioned is sufficient or not. Someone told me that I have to increase Acid Electroclean (-) and Alkaline Electroclean (+) to prevent nodules after Bright nickel especially for steel. Is it true?

Thank you

Aon Dum
- Bangkok, Thailand
^


May 18, 2012

A.Hi.
You can go for Periodic reversal polarity alkaline electro cleaner instead of Acid Electrocleaner (-) in the first stage after soak cleaner, be ensure that the cleaning cycle starts with anodic (+) and ends with anodic (+). In the second stage of alkaline cleaning you can go for anodic alkaline cleaner.

P.Kumba
- India
^


May 18, 2012


A. A picture can help the readers, I am just trying to figure out how can I help.

Alkaline cleaning soak or electrocleaning plus acid dips remove grease/light oils and soil from parts.

A failure in cleaning, gives you poor adhesion and spots, mostly, sometimes blistering.

in severe acid attack of the surface you find etching that lead to a bad appearance of the parts.

Can the nodules be the result of insoluble matter suspended on the bath? (Metallic particles from a basket bag, dust from abrading operation?)

Once I saw a problem in the bath similar to "wrinkles" on deposit. it was removed with filtration and carbon treatment.

Also one of the best medicines for a bath is the work! A lot of it.

Good luck

Daniel.

Daniel Hernandez
- Bucaramanga Santander Colombia
^

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