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topic 22320 p.3

What is a Hull Cell Test, Why is it done, Where to Get a Hull Cell




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A discussion started in 1997 but continuing through 2020

September 22, 2008

Q. Hi all,

I've been using a hull cell to evaluate the best plating parameters for a sulfuric acid copper chemistry. I now have the ideal additive ratio and current density but how do I figure out the current density of my piece in my larger plating bath. Also in my bath the anode-cathode separation is much larger than the hull cell.

Is there a rough equation for determining the current density at a point x distance from the cathode? Or do I just have to play with the settings?

Any help appreciated,
Thanks,

David

David Fitz
Student - Ireland


October 1, 2008

A. Hi, David. Figuring the average current density should be no trick. You just divide the total amperage by the surface area of the component, and it doesn't matter what the anode to cathode spacing is. The current density will vary across the component -- highest at edges and corners, lowest in the middle of expanses. Anode to cathode distance matters for this, but probably not at much as the geometry of the part. Software is available for modeling current density across a part but it's not a trivial calculation and more likely involves finite element analysis.

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


November 11, 2008

A. When using Hull Cell the volume utilised is quite small and depletion of metal and or brighteners occur at a surprisingly high rate.

Its a good idea to use a perforated cell in a larger volume of electrolyte so that the electrolyte remains relatively constant.

Mel Platt
Mel Platt
geriatic mel - Maidenhead, U.K.


November 13, 2008

A. The Hull Cell is an excellent tool for determining how an electrolyte acts under different current densities. The current density at any particular point on the Hull Cell plate will be dependent on the current applied to the cell, and there are standard Hull Cell tests that will tell you these values. When transferring this information to a real plating cell, the difference is that the anode-cathode distance should be the same for as much of the plating part as possible, otherwise you will get differential plating rates. Once you know the optimum current density for plating from your Hull Cell test and have calculated the surface area of your plating part in your larger tank, you can work out the total current you need to apply to your part. In practise, the greater the anode-cathode distance, the better the thickness distribution will be.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK



April 15, 2012

Q. Hello Sir,

I am doing my deposition of copper using Comsol Software. How can we convert the current intensity in terms of dm^2 ?

Lohith Pemmasani
- Furtwangen, Germany



April 23, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hello,
I am a student in chemical engineering and I am doing a research on Hull Cell Testing.
And I need informations on how it works, like the operative methods, and how to analyse the results, so if you can write it to me or give me some links about it, I will be very thankful.
Thank you

jack boston
- Paris, France


April 2014

A. Hello Jack. We appended your inquiry to a long and interesting thread on the subject. So please read it and think about what you would like to research in particular, then ask a specific question and we'll try to help. Good luck.

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey
Striving to live Aloha


March 29, 2017

A. Try Larry King Corp

I did business with them for years. They sell the cells, the flat panel cathodes, and anodes.

You can make your own 500 ml Hull cell. I did. Check out the dimensions and get the plexiglass pieces cut. Plexiglass is very easy to join with solvent cement.

dave wichern
Dave Wichern
Consultant - The Bronx, New York



March 28, 2017

Q. In a Hull Cell can I use as a cathode a part (not flat) that needs to be coated?

Julia Savchenko
- Austin, Texas, USA


March 2017

A. Hi Julia. No, certainly not.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading


March 29, 2017

Q. The part that I need to coat is magnet NdFeB; can I use cathode made out of NdFeB in a Hull Cell or in a Rotating Cylindrical Hull Cell? Thank you!

Julia Savchenko [returning]
- Austin, Texas, USA


March 2017

A. Hi again. I guess you are not asking about using a hull cell for the purpose it was intended (as a testing device), but simply using it as a small general purpose electroplating tank for your magnet ...

It's not ideal for that for a few reasons, including the fact that a hull cell is designed to plate only one side of an item rather than both sides. I think you'd be better off using a glass beaker so you can put an anode on each side of the cathode and so you can more easily use a magnetic stirrer for agitation. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading


March 30, 2017

thumbs up sign Thank you very much for taking the time to answer my questions.

Julia Savchenko [returning]
Urban Mining - Austin, Texas, USA


March 31, 2017

A. I would use a plastic polyethylene shoebox as a plating tank.

I'm not clear on what is being plated here. I was plating Cu and I used 3/8" copper tubing as anodes. I flattened little sections at one end, drilled holes, and joined them to the mickey mouse "busbar" with brass screws. Worked fine.

Ni would be tougher. Anodes there are generally Ni "crowns" and you would have to have some kind of conductive anode basket to contain them.

dave wichern
Dave Wichern
Consultant - The Bronx, New York



November 1, 2017

Q. Hello, I'm about to start an experiment about analysing the thickness distribution of an electrolytic bath, I'm looking for information about different cells that I could use in the lab, but can't seem to find information about cells but Hull's. Does anybody know where I can find this kind of information, or suggest any cell suitable for this experiment?
Thank you in advance.

Ricardo Escobedo
- Sonora, Mexico


November 2017

A. Hi Ricardo, there are many styles of Hull Cells including perforated hanging hull cells (for use within a plating tank), double size (534 ml) cells, 1000 ml cells, and "jiggle cells". There is also a different kind of test cell calling a Haring or Haring-Blum cell which is used to measure throwing power; but which can be used for thickness distribution measurements as well.

But it seems to me that a Hull Cell is the ideal tool for thickness distribution determinations. There are youtube videos specifically about this; here is one courtesy of EPI (Electrochemical Products Inc.) [a finishing.com supporting advertiser]...

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading



May 25, 2020

Q. Hello,
I have a Hull cell in my lab (around 267 ml cell, I think). I am trying to perform Hull cell tests with some nickel baths. My Hull cell plate has an immersed surface of 50 cm2 (5 x 10 cm). My bath works at 1.5 A/dm2. How many amperes should I use : 1.5 x 0.5 = 0.75 A. Is it correct? I have seen that we should use 1, 2 or 5 A with use cell (as noted in many hull cell ruler). What is right?
Another question, I have forgotten my Hull cell ruler. Is it possible to draw/create my own Hull cell ruler? How to do it? Could you help me please?

Thank you in advance
Best Regards

Thomas

Thomas Perrier
- Berne, Switzerland


May 2020

Hi Thomas.

adv.
Download the EPI Finishing Utility app and you'll have your ruler, plus other stuff :-)

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading


May 29, 2020

Q. Hello,

Thank you Ted for your reply! This app looks great but unfortunately impossible to download it on my phone or tablet: This app is not available in your country :(

I will try to construct my own Hull scale. If someone can help me to construct my Hull scale, let me know please. I need to know the current density distribution on the Hull cell pate. And about the current to use, can we use whatever we want or is it advise to use 1, 2 or 5 A as specified in the Hull cell ruler?

Thank you in advance

Thomas Perrier
- Berne, Switzerland


May 29, 2020

A. Go to google.com - images - and search for hull cell ruler pdf and you will get a lot of choices. Even in the restrictive climate in the EU that shouldn't be a problem.

tom_rochester
Tom Rochester
Plating Systems & Technologies, Inc.  
supporting advertiser
Jackson, Michigan, USA
plating systems & technologies banner ad


June 4, 2020

Q. Hello,

Thank you Tom for your suggestion! Good idea, I had not thought about it!
I saw this formula in this thread :
c=i(5.1-5.25logx)
c= current density
i= current applied
x= distance to be measured on the panel (panel side close to anode is HCD area and side away from anode is LCD area)

What are the units in this formula?

Do you think I can use it to construct my own Hull cell ruler? But with this formula, current density will be infinity at x = 0, possible??

Thank you,
Best Regards

Thomas Perrier
- Berne, Switzerland


June 2020

A. Hi Thomas. I don't have the reference which offers that equation, but it seems to be more of a "curve-fitting" formula than a derivation based on first principles.
Current density is most often expressed in A/dm2, and it must be in this case because were it measured in A/m2 or A/cm2 the current density would be 100X lower or 100X higher, and that sounds unreasonable.

Since a Hull Cell panel is 10 cm long, and log10 = 1, x must be measured in centimeters. At a current of 1 amp then,
CD at 1 cm from HCD end is 5.10 A/dm2
CD at 5 cm from HCD end is 1.43 A/dm2
CD at 8 cm from HCD end is 0.36 A/dm2
CD at 9 cm from HCD end is 0.09 A/dm2.

My limited understanding is that the formula is considered valid and usable only between 1 and 8 cm from the HCD end, so the fact that log0 is undefined and approaches negative infinity doesn't matter.

Luck and Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading


June 9, 2020

thumbs up sign Hello,

Thank you Ted for your comments! I will try to construct my own Hull cell ruler with this formula.

Best Reagards

Thomas Perrier [returning]
- Berne, Switzerland



October 20, 2020

Q. Hi, I don't see anything on this thread about chrome plating hull cells. I have a chromic acid plating bath that I would like to track with a hull cell from time to time. We have one onsite, it's poorly constructed, doesn't seem to be a standard size (267mL, for example), and doesn't have a heater. It's made of porcelain, I believe. Are there any other materials that can be used for chromic acid? Can you recommend a chromic acid hull cell? It would also be helpful to be able to heat the solution in the hull cell.

I am also wondering what the best settings for running a chrome hull cell would be - run at room temperature for consistency? 5 amps? 10 minutes?

Paul Langford
- Eau Claire Wisconsin


October 2020

A. Hi Paul. I have no hands-on experience with hull cell testing, let alone for chrome plating, but you must run it at operating temperature, not room temperature. My understanding is that a perforated hull cell is suggested for chrome plating because of the otherwise fast temperature rise.

It seems that one approach is to hang a porcelain perforated cell in your chrome tank, whereas another approach suggested & offered by www.yamamoto-ms.co.jp/en is to place the 267 ml perforated hull cell into a 1000 ml enclosure tank -- I'm not sure of their material of construction but I don't think it's porcelain -- lots of plastics are resistant to chrome.

Although there are guidelines for time to run hull cells, in your case of decorative chrome, I would think you would want to run it for the same amount of time as your plating time the first time around to get a feel for coverage, and 5 A sounds right.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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