HOME FAQs BOOKS JOBS: Help Wanted Suggestions you are here: Hotline/Forum => Letter 28232
Nickel electroplating problem
++++
I am currently doing an investigation on Nickel elctroplating in school. I am having problems as every time I try to electroplate onto a Copper sheet I always get a layer of Nickel(II) Oxide and no Nickel metal. I have tried using different current densities and concentration of substrate solution( Nickel Chloride). However, I have found out that when I use Ammonium Nickel Sulphate I get a nice shiny coating. Can someone please explain why this is the case?
Thank you very much,
Waseem A.Chemistry investigation - Glasgow, Scotland, UK
++++
Interesting....The only thing I can think of is that nickel is usually electroplated at a pH of about 3.5 to 5 (in round terms). I do not know the pH you used with nickel chloride, but I suspect it will be at least 5 and perhaps higher. This will result in the nickel oxide being put down. When you used ammonium nickel sulphate you had the solution buffered at a suitable pH (ie between 3.5 and 5). However, I am surprised you got a bright deposit, unless it was very thin and on to a bright brass plate.
|
Trevor Crichton R&D practical scientist The Pheasantries - Chesham, U.K. |
++++
Thank you very much for your help. Could you please suggest what I could investigate as a result. My teacher says I should try varying the concentrations of Ammonia and Sulphate but after reading your very generous suggestions, I feel this may be a waste of time and I do not have a lot of time to waste. I was thinking I could maybe try finding an optimum pH at which the nickel electroplating occurs. I was using copper sheets which polished before I used them and I had a very thin layer of nickel plated onto it.
Thank you very much.
Waseem Afzal- Glasgow, Scotland
++++
I would suggest a bath comprising 300g/l nickel sulphate, 30g/l nickel chloride, 40g/l boric acid. Operate at pH = 3.8-4.2 at about 50C. Cathodic current density about 40ASF, anodic cd about 50ASF. This is known as a Watts nickel bath.
Add about 0.5g/l sodium saccharin to harden and brighten it. If you wnat to be really clever, add about 10g/l cobalt sulphate and this will also brighten and harden it.
|
|
Trevor Crichton R&D practical scientist The Pheasantries - Chesham, U.K. |
++++
Hi,
The best method to electroplate nickel is definitely the way Mr.Trevor has suggested. It is a conventional watts bath. A few more things... the pH of the bath has to be in the range of 4.8 to 5.4 and the current density 10 to 15 Amperes/Square feet..Also the surface cleaning and activation prior to the plating is most essential.
Mukund Shindechemical co. - Mumbai, Maharashtra, India
September 3, 2008
I am doing a semi-similar investigation for my advanced higher investigation, and have found that I also get the best results using a Watts Nickel Bath. My recipe for this is 52.5g nickel (II) sulphate, 7.5g Ammonium chloride and 7.5g boric acid in 500cm3 water. This works best around 35 oC and you need a nickel anode obviously.
What I am investigating is the difference produced when varying pH, temp, and current density [current per unit area of cathode immersed] this worked well for me. Good luck
- Dumfries, Scotland