Romix
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Electroplating
Galvanized handles on my buckets began to rust.
How to electro plate then in nickel?
Nickel anode, electrolyte nickel chloride, handles cathode.
Would it work? What about chlorine, would there be any produced?
[Edited on 18-8-2016 by Romix]
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Zandins
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Anode:
2Cl--2e- --> Cl2
Cathode:
2Zn+ + 2e- -->2 Zn
In summary, zinc is plated onto the cathode, while chlorine is released at the anode. Therefore, the method is workable.However, take note of the
following concerns:
1)The standard potential of hydrogen reduction is lower than that of chlorine, therefore as the concentration of ZnCl2 decreases, the electrolysis of
water will start to predominate. The exact concentration for it to occur can be calculated from Nernst's equation;\
2)I can not advise on the strength of the nickel coating, perhaps it will be brittle and flake off?
3)The amount of chlorine produced does not pose a lethal hazard; nevertheless, good ventilation should be provided for safety. If the electrolysis is
carried out at 1A, it will release 22.4*3600/(2*96500)=0.41L of chlorine per hour.
[Edited on 18-8-2016 by Zandins]
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Melgar
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You probably also want to remove the rust and the remainder of the zinc before you electroplate onto the steel. Electroplating nickel onto zinc just
seems like a bad idea. You can remove both with a dilute acid. HCl would work fastest but would corrode the steel. Phosphoric acid would be ideal,
since iron phosphate makes a decent passivating layer on steel, which is why that's what they use in most commercial rust removers.
Are you using a commercial nickel-plating solution or are you making it yourself? Nickel sulfate is what they typically use commercially, along with
additives to control what the finish looks like.
[Edited on 8/18/16 by Melgar]
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Romix
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Quote: Originally posted by Melgar  | You probably also want to remove the rust and the remainder of the zinc before you electroplate onto the steel. Electroplating nickel onto zinc just
seems like a bad idea. You can remove both with a dilute acid. HCl would work fastest but would corrode the steel. Phosphoric acid would be ideal,
since iron phosphate makes a decent passivating layer on steel, which is why that's what they use in most commercial rust removers.
Are you using a commercial nickel-plating solution or are you making it yourself? Nickel sulfate is what they typically use commercially, along with
additives to control what the finish looks like.
[Edited on 8/18/16 by Melgar] |
That's right. KOH will work fine for zinc. Would nickel plate on to steel?
What will happen electrolysing it through sulohate, SO2, SO3?
[Edited on 19-8-2016 by Romix]
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Romix
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In highly concentrated ammonia conditions nickel will begin to rust too.
What about silver, is it possible to plate steel in it?
And it will darken too, with time.
[Edited on 19-8-2016 by Romix]
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Melgar
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Yes, nickel will plate onto iron, and assuming your handles are galvanized, that's probably the only metal in them underneath the zinc. I was looking
into making my own soldering iron bits, and my research indicated that to do it properly, you have to plate the copper bit with iron, then plate
nickel onto the parts that you don't want solder to wet.
Really though, with electroplating, a major concern is metal atoms diffusing through the various layers, which is why nickel is typically put down as
a base layer, since it's pretty good at keeping metals from diffusing through it. Copper is then plated onto nickel, because it works the best for
further plating with gold and chrome. (Hence the reason cheap metal stuff turns a copper color when the chrome plating is worn away) Silver is really
bad about diffusing into other layers, and I'm not sure you'd be able to plate it onto iron anyway. You can't plate silver directly onto copper
either, or it'll turn a splotchy bronze color after a few days. I believe you can plate it onto nickel without any major problems, except for the
fact that in order to properly silverplate anything you need its potassium cyanide double salt. Same goes for gold. You can purchase plating
solutions that take away a lot of the risk, but you seem more interested in making your own plating solutions, in which case, nickel is probably the
way to go.
As far as the sulphate ion, the reason they use it is because it does virtually nothing in solution except carry a charge. In the rare instance that
it gets oxidized to O2 and SO3, that SO3 doesn't waste any time reacting with water to form H2SO4 again. Usually the potential is too high for that
though, and you just get oxygen at the electrode.
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Romix
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| Quote: Originally posted by Melgar | Yes, nickel will plate onto iron, and assuming your handles are galvanized, that's probably the only metal in them underneath the zinc. I was looking
into making my own soldering iron bits, and my research indicated that to do it properly, you have to plate the copper bit with iron, then plate
nickel onto the parts that you don't want solder to wet.
Really though, with electroplating, a major concern is metal atoms diffusing through the various layers, which is why nickel is typically put down as
a base layer, since it's pretty good at keeping metals from diffusing through it. Copper is then plated onto nickel, because it works the best for
further plating with gold and chrome. (Hence the reason cheap metal stuff turns a copper color when the chrome plating is worn away) Silver is really
bad about diffusing into other layers, and I'm not sure you'd be able to plate it onto iron anyway. You can't plate silver directly onto copper
either, or it'll turn a splotchy bronze color after a few days. I believe you can plate it onto nickel without any major problems, except for the
fact that in order to properly silverplate anything you need its potassium cyanide double salt. Same goes for gold. You can purchase plating
solutions that take away a lot of the risk, but you seem more interested in making your own plating solutions, in which case, nickel is probably the
way to go.
As far as the sulphate ion, the reason they use it is because it does virtually nothing in solution except carry a charge. In the rare instance that
it gets oxidized to O2 and SO3, that SO3 doesn't waste any time reacting with water to form H2SO4 again. Usually the potential is too high for that
though, and you just get oxygen at the electrode. |
Good, thanks for help.
[Edited on 19-8-2016 by Romix]
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Melgar
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I just realized I mixed up copper and nickel as far as plating order. Copper is typically put down first as a base layer, because it has good
adherence to steel, as well as a bunch of other metals. Nickel is then put down as a barrier layer, then chrome, silver, gold, or whatever the finish
layer will be. Also, electroplating is really more of an art than a science, and minor variations in plating technique can result in quite a
difference in surface finish quality.
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