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Electroforming of Nickel -- Nickel sulphate & Sulfamate Experiments

adv.  

2006

Q. I would like to recover the nickel from nickel sulphate solution (contain small amount of impurities, e.g. : 0.12 g/L of Fe), I do a small scale experiment and my experiment do not give me the satisfied result as the plating is thin (0.5 g obtained) and the Nickel that plates on the cathode is not pure (around 90% of Ni and 10% of iron).
The condition of the experiment was as follow:
- 3 voltage of power supply
- Stainless steel cathode and Pure nickel Anode immerse in 1000 ml of
- 65 g/l Ni in NiSO4 solution
- 10 g/L of boric acid used as Buffer.
- pH of electrolyte= 0.9 and temperature used = 40 °C.
- duration of electroplating = 7 hours

My aim for the experiment is to gain the pure nickel plating as thick as possible. Thanks for anyone who can give me comment on my experiment.

Hafel
Metal Recycling - Malaysia

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A. SS anode will corrode and will decrease the purity of the plated material. Platinized titanium or similar insoluble anode would be needed. You need superior agitation as the plate rate will decrease as the amount of nickel in solution goes down. Your pH will rapidly go out of the desired range and basically stop plating. Raise the pH with a dilute caustic as required. Dilute or you will have a violent reaction. PS, it is not cost effective! James Watts - Navarre, Florida 2006 A. Look up the composition of a Watts Nickel bath and try to replicate that with your chemicals. Your boric acid is too low, pH too low, temperature can be increased. You will need to remove the iron, so do a low current density plate-out. then you will be able to recover your pure nickel. Trevor Crichton R&D practical scientist Chesham, Bucks, UK 2006 A. If your objective is to recover Ni from NiSO4 solution, then you should use inert anode (such as platinized titanium anode), otherwise nickel keeps dissolving from anode into bath solution while plating out on cathode. For Fe impurity, you may apply low current density (~3 asf) for a few hours to dummy out Fe onto a separate cathode first then apply normal current density (~25 asf) to plate thick nickel onto stainless steel to get a high purity Ni deposit. David Shiu - Singapore 2006

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Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)

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High School Science Fair Idea: electroforming?

Q. Hello,

I am an 11th grade student looking for a science fair project. After searching for many hours I came across electroplating. This interests me not only because it involves chemistry but because it has a practical application. I was wondering if you could suggest a "High School Level" experiment. This could include varying the metals, varying the solutions, etc. I have access to my school's chemistry lab to conduct my experiments and can order the necessary chemicals, so technicality is not a problem.

Thanks for your time.

Adam M. [last name deleted for privacy by Editor]
student - Middletown, Pennsylvania
2003

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Chemistry experiment using sodium hydroxide Sodium Hydroxide Q. Hi, I am doing a chemistry assignment on sodium hydroxide and was wondering if there are any experiments I can put in my assignment that uses sodium hydroxide or creates it. Stacey Boogaard - Perth, Australia 2002 A. Hi, Stacey. As I explained to Adam, sodium hydroxide (caustic soda [affil links] ) will dissolve aluminum, and that fact might give you some ideas. As another tack, please research how aboriginal people made soap, and then try your hand at making some :-) Caustic soda (sodium hydroxide) is used in the manufacture of soap today, and you may find out why it's better and/or easier than the old fashioned way. It should be a pretty good experiment. Sodium hydroxide is a very powerful alkali, so if you are actually doing experiments with it, you need some training from the science teacher, and need to wear goggles [on eBay or Amazon] and rubber gloves [on eBay or Amazon] (if not more complete personnel protection equipment). Good luck with it. Ted Mooney, P.E. Striving to live Aloha finishing.com - Pine Beach, New Jersey

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Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)

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Treeing (dendrites) in Ni Sulfamate Electroforming

Q. I am a student attempting to create an electroformed Ni plate that is 4 x 10 cm and 1 cm thick. To do this I have created an acrylic frame to cover a Cu cathode, allowing plating only in a 4x10 area. At thicknesses over 1mm, I have been getting severe treeing around the inside edges of the frame and large nodules on the plated surface.

I am using a chloride free Ni sulfamate bath (Ni-speed) at 50 °C, using a magnetic stir bar for agitation. I filter my bath at 0.22 microns before each attempt. My surface tension is about 35dynes/cm and I have tried a current density of 10 and 18 A/dm2 with no change in dendrite formation.

I have added 0.2g/L of butyne diol. The plate became very shiny, but the dendrites still formed.

Any suggestions to at least decrease dendrite formation?

Ben Poquette
Student, Virginia Tech - Blacksburg, Virginia
2006

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A. In reality you are putting down one hell of a lot of nickel! The treeing and nodules are caused by microscopic asperities on the electroforming surface and these generate localised high current density spots; - once that happens the process starts to run out of control and produce unwanted growths. The art in electroforming is to try to prevent this happening. The science in electroforming is to get it right! Having looked at your conditions, they seem pretty good, although you don't give much detail of the bath composition. You may want to increase the temperature to the upper 50's or low 60's, but DO NOT exceed 70C. The asperities can be reduced by having a high filtration rate - I reckon on 10-12 tank turnovers per hour, but others will say less because filtration can take out additives. Nevertheless, my way has been quite successful. You will also get build up at the edges of the frame as this is an area of high current density - you may want top consider using a robber framework to help reduce it and divert the current back to the centre of the plate. I think that whilst you are trying to achieve such high thicknesses, you are bound to get surface asperities, so one way is to take out the electroform on a regular basis and machine the surface back to a smooth one. Then reactivate the nickel and continue electroforming. another alternative is to use pulse plating - this may well reduce the effects of the asperities, but it should be used with high filtration rates. Good luck. Trevor Crichton R&D practical scientist Chesham, Bucks, UK 2006 A. Your best chance will be to turn the cathode to a vertical position and increase the anode to cathode distance to 4 inches. Then rig an air agitation sparger directly under the part. A good way to do this is to use a fish tank air pump. Do not use the "air rock" as it will dissolve in the acid. Use some vinyl tubing, heat the end and pinch it with pliers. Then, heat up an unbent paperclip to red hot and make a hole in the tubing. Put holes about 1/4" apart in the required area. You can use a fine stainless wire to tie the tube to a heavy SS rod. Next, your amperage is too high. 50 amps per sq ft would be better and that may be high. That is about equal to 5 amps per sq Dm. Finally, you may have to put a wire "thief" or "robber" around the outside of your frame, just outside of the slit to knock down the high current density area of the part. This has to be hooked up to the negative terminal also. change the wire size as required. James Watts - Navarre, Florida 2006

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2006

Q. As for my bath composition:

600 g/L Ni sulfamate
16.5 g/L Ni Chloride (I added this since my orig. post)
35 g/L Boric acid
0.2 g/L SDS (surfactant)
50 °C
pH 3.6

In the meantime I have carbon treated my bath and discontinued the use of organic levelers. I have also decreased my current density to 8 A/dm2. This has left me with a fairly nodule free surface at thicknesses up to 2mm, except at the edges (high current density areas).

I will try the air agitation and a current density between 3-5A/dm2. My cathode position is vertical, sorry for the misleading picture. I cannot however filter my bath during plating as I plan to eventually add ceramic particles which I hope will become embedded in my Ni plate to serve as a reinforcement in the electroform.

I will experiment with a robber system, but today I tried adding a plexiglass shield between the anode and cathode. This shield has a rectangular hole in it, just smaller than the area to be plated.

Thanks guys,

Ben Poquette [returning]
- Blacksburg, Virginia

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Q. Trevor and James,

Thank you so much for all of the help. I have been filtering the bath to o0.22micron prior to use and this has helped a lot.

One more question: Since I may need to use a ccd as low as 2 A/dm2, would it help to use a bath of lower Ni sulfamate concentration? Could this act to level my bath by making it easier for the solution to become depleted at the tips of nodules and dendrites, thus slowing them down?

Also, as a side note, are there any electroforming classes and/or internships that you could suggest?

Ben Poquette [returning]
- Blacksburg, Virginia
2006

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Multiple threads were merged: please forgive repetition, chronology errors, or disrespect towards other postings [they weren't on the same page] :-)

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Peeling problem with nickel electroforming

June 7, 2012

Q. I am not a chemist nor am I a professional at electroforming. Circumstance has made me the person in charge of electroforming at my laboratory. I did not have a mentor nor a background in electroplating before I started.

I am operating the German-made electroforming unit.

The processing parameters are as following;

Temp : 52 ~54°
pH : 3.8 ~ 5
Total volume of electrolyte : 240 liters
Flow rate of electrolyte : 64 liters/minute
Concentration of Ni(NH2SO)2 4H2O : 345 ~ 355 grams/liter
Concentration of NiCl2 6H2O : 5 grams/liter
Concentration of H2BO3 : 35 grams/liter

One day I conducted few electroforming experiments and found that there were something wrong with my result.

The electroformed surface is not as good as before.

I do maintenance task regularly and do not know what to check for sorting out the problem.

For better explanation, I attached the pictures of the result.



Could anyone please check the result and give some feedback if anything has to be checked ( for example, electrolyte, cell, pH, Temp or else)

I have been electroforming for about one year and I have never had this kind of problem.

Any comments will be appreciated.

Taekyung Kim
- Seoul, South Korea

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Q. I am very thankful for your comments.

However, I have a question on your comment.

Could you please tell me the meaning of turnover?

Do you mean that I should decrease the flow rate of electrolyte by half?

Cheers mate! TA!

Taekyung Kim [returning]
- Seoul, South Korea
June 20, 2012

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September 24, 2020

Q. I have conducted an experiment of electroforming using stainless steel as a mandrel and nickel sulphamate as a solution using 1 L beaker [beakers on eBay or Amazon]. The size of stainless steel mandrel is 4 cm x 13.5 cm. Sodium Dichromate was used approximately 2 g and dissolved in 1 L of distilled water.

  

        

Mandrel was dipped into Sodium Dichromate solution for 2 minutes whose purpose is to have a passivation layer, and rinsed with distilled water. Then electroforming process with the setting voltage of 20V conducted for 1 hour. I have used simple agitation using magnetic stirrer.

After 1 hour, mandrel was rinsed and it was detected that it builds up with crystalization at the side of the mandrel. Thus, using a sand paper to smoothen the side of the mandrel. Upon completion of sand paper, both side able to separate but the front surface are not the same as nickel foil.

It was also detected that anode basket rusted/corroded and effected the Nickel Sulphamate solution which turned cloudy and there was a residue.

     

Unsure whether this anode basket is made from SS or GI. Is the anode basket from SS rust? Is the solution able to use it again? Can an anode basket from SS can be used?

It would really be helpful if any of expertise can share any information and feel free to comment.
Thank you.

Sazlin Lin
- JB Malaysia

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October 5, 2020

Q. Hi,
I have changed the material basket to titanium and have applied 2V, 0.2 A for the experiment. Here is my composition:
Nickel sulphamate: 350 ml
Nickel chloride: 10 g/l
Boric acid: 37.5 g/l
pH: 4.6
Temperature: 42 °C
Agitation: using magnetic stirrer

The stainless mandrel was cleaned using soap and acetone [on eBay or Amazon]. I also make a passivation layer using sodium dichromate 2 g/l for 2 minutes. After electroforming for 1 hour, the mandrel was immersed into a beaker of distilled water for 2 minutes. Unfortunately, the surfaces of electroformed nickel still look cloudy and dark.

        

Is there any usage of chemical after electroforming process? I managed to peel off the electroformed layer but the only issue that I'm facing now is the surface of electroformed nickel.

It would really be helpful if any of expertise can share any information and feel free to comment.
Thank you.

Sazlin Lin [returning]
- JB Malaysia

adv.