netneut
finishing.com -- The Home Page of the Finishing Industry
A website for Serious Education, promoting Aloha,
& the most FUN smiley you can have in metal finishing


Finishing.com has been free for 22 years,
but without net neutrality we could soon
cease to exist. Do us a solid, click on
the banner, and contact congress today!
HomeFAQsBooksHelpWantedAdvertiseForum
topic 7124

Nickel Buildup In Bright Nickel Solutions


(2001)

We are experiencing build up of nickel in our bright nickel electroplating solutions. As a result we have to remove solution and dilute intermittently. What causes this and what can we do to get a balance?. We are unable to return dragout to the tank due to this buildup. We use nickel anodes in titanium baskets.

Bert J. Sherwood
- Los Angeles, California USA


First of two simultaneous responses-- (2001)

The reason nickel conc. increases is due to the difference in efficiency. The nickel dissolves from the anode at 100% efficiency whereas the nickel deposits on the cathode at 95% efficiency. Thus the increase in nickel in your solution. One way to minimize this increase in nickel concentration is to use insoluble anodes for some of the soluble anodes but the anodes need to be separated from solution by a membrane or your plating solution will get out of balance. There are proprietary systems out their that can solve your problem.

George Shahin
George Shahin
Atotech - Rock Hill, South Carolina


Second of two simultaneous responses-- (2001)

Your anode efficiency is greater than your cathode efficiency. Either raise the cathode efficiency (could be a contact problem or a chemistry problem) or lower the anode efficiency (less surface area). Another point: is this a new problem, or one you've had for a while? Has anything changed?

James Totter
James Totter, CEF
- Tallahassee, Florida


(2001)

We have experienced this problem in the past and remedied it by decreasing the anode area by removing a basket.

E. MacKenna
- Houston, Texas


(2001)

Hello:

You have got some good replies for your query. I will try to tackle it in a slightly different way. Mostly when nickel solution builds up, it is Nickel Sulfate which increases. The simple reason being the difference in anode and cathode efficiencies and the general habit of adding sulfuric acid for pH adjustment.

What happens in these build up problems, we stop adding nickel sulfate but we still add nickel chloride because it goes down as the bath plates.

We can manipulate a little here, instead of adding sulfuric acid we can add hydrochloric acid which further replenishes the required nickel chloride and also adjusts pH. But we do not end up increasing the nickel metal concentration in the bath as we are not adding any nickel salt. So now you have 3 options or I would prefer a combination of all 3:

1. Adjust your anode to cathode ratio (also you want to see if all anodes and cathodes are getting the right amount of current).
2. Use some insoluble anodes.
3. Start using hydrochloric acid for pH adjustments.

If I were you I would prefer a combination of 1st and 3rd approach.

Regards,

Hemant Kumar
Hemant Kumar
- Florida, USA


(2001)

Hi, Mr Hemant Kumar Bansal

I have read your article and I find it very interesting about the nickel sulfate increase and nickel chloride decrease. I am not quite sure how does it work, is that like nickel chloride will use up in the plating process, therefore more nickel chloride will need to add to the solution, and that causing the nickel build up?

Other thing is that where did the chloride go? Do they become chlorine gas and release to the atmosphere?

Thanks

Chi Cheng
- Baltimore, Massachusetts


(2001)

Hi Chi Cheng

I am not saying that in nickel plating, nickel sulfate increases and nickel chloride decreases.

Because generally we add sulfuric acid to control the pH of the bath so it creates more sulfate ion in the bath which eventually end up in increasing the nickel sulfate concentration. Whereas nickel chloride is consumed as chlorine is evolved at anode and at the drag out(basically nickel chloride's function is to provide solution conductivity whereas nickel sulfate is the primary source of nickel ions, essential in the plating).

As we do not add hydrochloric acid so we end up going down in chloride concentration and we have to add nickel chloride and not nickel sulfate.

Here is a danger. Each addition of nickel chloride is further increasing NICKEL ION as well which reacts with sulfate ion of sulfuric acid and create more nickel sulfate within the bath.

These situation worsens if we have minimum drag out.(Principally we try to reduce drag out but it does not help if we have already high nickel concentration).

To be short, I think sometime we may add hydrochloric acid instead of sulfuric acid. But be careful it reacts faster.


Hemant Kumar
- Florida, USA

(2001)

Thanks for your response, it really gives me a much clearer idea now. But you mention about the adding of HCl will have a faster reaction, would you tell me more about that? Is that the pH will drop faster? A stronger exothermic reaction? Is there any problem to do it in practice?

Also how much should I put in? Can I use a simple mass balance to calculate the amount to add?

And for your solution 1, about the efficiency, how can I find out/calculate the efficiency of the system? Is that based on surface area, is that a book I can read?

Again, thanks a lot!

Chi Cheng
- Baltimore, Massachusetts


First of two simultaneous responses-- (2001)

Dear Chi

Do not worry about HCl additions. In Nickel plating you can start adding it without any difficulty. pH drops little faster but you can continuously measure it to see how much you need.

The efficiency of Nickel plating you can generally assume at 95%. Its hard to check the efficiency in the lab but you can deposit some plating on a mandrel and measure the weight deposited versus ideal deposition (based on Faraday's laws).That is your % efficiency.

Regards


Hemant Kumar
- Florida, USA

Second of two simultaneous responses-- (2001)

I do not know of anyone else with your problem. At 140 degrees F, a bright nickel bath will usually have enough evaporation to allow replenishment with some of the dragout. Everybody adds liquid to a nickel tank because the solution level falls; do you have a leak in a steam coil, or something like that? (rain leaks from the ceiling, etc.)

If you can increase your temperature to 145, you will use less brightener.

I don't understand how adding hydrochloric acid will help your problem, and you can only add so much before your chloride will get too high.

Is there something unusual about the way you are running this nickel? What kind of dragin/dragout do you get with your parts? Do you have a drip cycle going in that is longer than the drip leaving the tank?

tom pullizzi portrait
Tom Pullizzi
Falls Township, Pennsylvania


(2001)

Dear Hemant Kumar Bansal

I have checked the previous data, there wasn't any example we added in nickel chloride to increase the chloride level, therefore I guess it is not the reason in our case.

About the efficiency, I didn't know much about the Faraday's law. Also is that right to calculate the efficiency by a lab experiment? Isn't there any effect by the actual plating tank itself, I mean the surface area, the nickel bag...etc.

Also, is there any possible effect from chemistry composition in the plating solution?

And again, if the efficiency is the main factor of this problem, what should I do?

Thanks

Chi Cheng
- Baltimore, Massachusetts


February 17, 2011

Hi. Everyone
I got the same problem for "Nickel Buildup In Bright Nickel Solution", I adjust pH use sulfuric acid or Hydrochloric Acid based on the nickel sulfate or nickel chloride Concentration.But the problem still here. Thanks!

Billy Zhou
- Midland, Ontario, Canada

July 12, 2011

Warning! too much chloride is not good for the ductility of the deposit.

In this way: as chloride increases the tensile strength goes up
Hardness goes up
ELONGATION GOES DOWN
INTERNAL STRESS GOES UP

For some applications one has to be careful; for example, on parts where welding is necessary, firearms, parts exposed to heat or parts which receive some kind of bending.

I suggest finding the cause of the build up if that is a problem.

Actually I don't know why the nickel build up is a problem or its consequences.
without measurement is difficult to say how much is too much.

Daniel Hernandez
- Bucaramanga Santander Colombia

August 30, 2011

We use R-round`s on bright Nickel. What should be the proper relation between cathodic-anodic area?
Thank you so much

Bernardo Roque
Process Engineer - Guadalajara, Jalisco, Mexico

August 31, 2011

Hi, Bernardo.

Approximately 2:1 anode:cathode ratio is typical. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2017 finishing.com     -    Privacy Policy
How Google uses data when you visit this site.