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Nickel plates okay in one barrel but not another

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Q. I am doing a project with Nickel on Nickel plating using sulfamate bath and 10V. First experiment, I got good result. Then I used slightly different barrel type, with same condition as in the first experiment, and there is no nickel at all on my nickel substrate. I have tried to change the net screen but still no nickel deposited.
all samples are same material in same size and wash in sulfuric acid before plating.

Anna Hamilton
- Taiwan
March 13, 2023

nickel book
The Sulphamate Nickel How-To Guide

by David Crotty, PhD & Robert Probert

A. Hi Anna.
Washing in sulphuric acid is not sufficient activation for nickel substrates, but I don't think you've given us any data from which to make conjectures regarding what went wrong. But what was the amperage and time in the first barrel and the amperage and time in the second barrel?

What is your experiment about, and what is the input data and output data? Thanks. Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

Q. Hi!
The experiment is for capacitor nickel termination where I connect the nickel electrodes with nickel by electrodeposition. So the nickel is supposed to be deposited on the nickel electrode. but the problem is when I used the first barrel, nickel deposited with no problem, but no nickel at all deposited with second barrel with the same set up. Both barrels use 10V, 5-6A, 50 °C, pH 3.5-4, for an hour.

I put the capacitors in the barrel with Fe balls and Zr balls (ratio 5:1) as the medium. The first barrel and second barrel have same volume. But the first barrel has wider net window than the second one. Do you think it affects the result?

61527-1a   61527-1b  

For the sulfuric acid wash, I was only thinking it is for cleaning the substrate only. What acid wash do you recommend for activation?

Anna Hamilton [returning]
student - Taiwan
March 14, 2023

A. Hi again Anna.
The reason I inquired about the amperage is that if you are consuming amperage it has to do something! As Faraday's Law tells us, when you pump all those electrons from the anode to the cathode, some ionic reaction is forced to occur to balance them. Ideally what happens is that positively charged nickel ions migrate to the cathode, encounter those electrons, and are reduced to metal atoms on the capacitors (or on the fill). If metal is not plating out, the electrons must steal hydrogen from the solution, which should result in a large amount of hydrogen gas evolving, and a sharp rise in pH due to the OH- ions left behind.

Understanding Faraday's Law, and that all those electrons have to do something, should help you get a handle on what is going on. If 5 Amps if flowing for an hour it's doing something, not nothing :-)

But sure, too small a mesh can interfere with current flow, solution flow, and maybe even ion flow and cause lots of problems. To a certain extent electroplating science is still empirical rather than fully based on first principles -- i.e., some things work, other things don't work, even if we don't understand everything there is to know about every flow gradient. And your second barrel apparently doesn't work :-)

Alkali rather than acid is usually used for cleaning, although I'm not sure if your capacitors are alkali-resistant. Usually, old nickel must be activated with a Wood's Nickel Strike or another specialty process.
Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey

thumbs up sign Thank you for the explanation. I will just fix the first barrel and use it :D

40 minutes immersing in ammonia will oxidize my capacitor; I shall find the suitable base solution for washing my capacitors.

Anna Hamilton [returning]
student - Taiwan

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