Melgar - 22-4-2018 at 17:53
I've tried to electroplate other metals onto steel so many times, and failed every single time. The only thing I've ever been able to successfully
electroplate has been coins, presumably because they're nickel-clad, and nickel is a good metal to plate onto.
Anyway, I wanted to plate copper onto steel, because the color difference is super obvious. I've used regular carbon steel that I polished really well
and cleaned, but without much luck. I've also use HCl to dissolve the zinc off galvanized steel, then tried to plate the steel underneath.
Now, I've learned that for copper, silver, and gold, the absolute best possible plating solutions require at least low levels of cyanide, which I
actually have in abundance. But the electroplaters out there are a cautious bunch and won't give me any useful advice on using KCN or NaCN for
electroplating copper.
I tried making a silver plating bath too, starting with silver nitrate, but the only text I could find for preparing it was from the 19th century, and
used all sorts of stuff that I'm sure we've invented superior alternatives to.
My end goal here is to make my own soldering iron bits, where I can fashion the shape of the tip however I want using a copper (or even silver) rod,
and then plate the appropriate metals onto it so that solder wets some parts and not others. There are other things I'd like to do with it too. I
have all sorts of copper salts, silver nitrate, and nickel chloride and sulfate. I know it's an art to getting it to look right, but at this point I
don't even care what it looks like, I just want to make soldering iron bits that are the shapes that I need.
Anyone have any experience with this?
wg48 - 22-4-2018 at 19:06
This pdf should help you Attachment: feplating.pdf (162kB)
This file has been downloaded 651 times
Fulmen - 22-4-2018 at 22:47
Plating onto a less noble metal is tricky as the salt tends to autoplate out due to displacement. This reaction dissolves the base metal, reducing
adhesion.
The solution is usually to employ a "strike bath" with a metal complex in alkaline conditions, cyanides are often used for this. But at least with
copper there are non-cyanide formulations available based on amine complexes. These baths are often somewhat tricky in use and has low deposition
rates, but it's only required for the initial strike. Once the base metal is covered a simpler acidic bath can be employed.
Finishing.com has a ton of information if you can find it, there's also the Metal Finishing Guide Book: https://metalfinishing.epubxp.com/t/12238-metal-finishing-gu...
[Edited on 23-4-18 by Fulmen]
brubei - 23-4-2018 at 01:30
I'm working in a electroplating line an i confirm that steel is plated with copper in a bath containing cyanide, Silver to.
CarlSagans_RayGuns - 23-4-2018 at 02:27
I use a Wood's nickel strike on steel. It only has two ingredients Nickel Chloride and HCl. The proportions are not critical. I make the Nickel
Chloride from Nickel Oxide I remove from old Ni MH batteries, and use 99% nickel welding rods as the anodes. Works great! The steel part must go into
the copper bath within a few minutes of being nickel plated.
Melgar - 1-5-2018 at 13:25
Huh. I guess the issue that's been a sticking point is that I don't have much experience electroplating, but I have several pounds of sodium and
potassium cyanide and am well aware of the precautions needed to use it. I'd actually kind of prefer the cyanide routes, just because then I don't
have to buy anything else.
I've read you're supposed to use a nickel layer before plating with anything like silver, gold, rhodium, etc. For people with nickel allergies,
palladium is recommended for jewelry. But it seems like the layer directly on top of the iron is usually copper? Then nickel on top of copper?
So I guess the thing to do is make a strike bath by carefully adding copper sulfate to a sodium cyanide solution until it starts getting really
difficult to dissolve any more. Then dilute that quite a bit with distilled water? I guess if pH is important, I need a better way of testing it
than the cheap Chinese test strips that came with some glassware I bought.
knowledgevschaos - 27-8-2023 at 18:34
This might be a bit late but here goes:
Be careful with cyanides in a copper solution!
Copper (II) cyanide will decompose into copper (I) cyanide and poisonous cyanogen gas.
From the sciencemadness wiki:
"Aqueous solutions of cyanide may be oxidized by copper(II) to form cyanogen. The gas is >89% pure and the yield is 41%:[1][5]
4 KCN + 2 CuSO4 → (CN)2 + 2 CuCN + 2 K2SO4"
http://www.sciencemadness.org/smwiki/index.php/Cyanogen