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Topic: Can electroplating be done with oxides instead of chlorides?  (Read 8303 times)

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Offline eazye1334

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Re: Can electroplating be done with oxides instead of chlorides?
« Reply #15 on: February 07, 2014, 12:50:28 PM »
@eazye1334
Could you give your experience as related to the original question posted here.
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but is it not possible to plate with oxides instead?
No, it's not possible that I know of, outside of cadmium. It's unlikely you'd have enough conductivity due to the solubility issues. Also, the hydrogen evolved at the cathode surface would form hydroxides with the oxide in the tank, wreaking havoc on the pH. Hydroxide formation is an unwanted occurrence already, so upping that concern would not be a good plan.

Chlorides also play a role in the properties of the final plating. For example, copper can be plated in a whole bunch of ways: acid copper, cyanide, pyrophosphate (the only neutral bath I can think of), fluoroborate, alkaline non-cyanide, etc. The only one of those to use chlorides is the acid copper, in which case they help to brighten the deposit and dissolve the anodes. Each bath has different throwing power, speeds, ductility, adhesion, etc. Some nickel baths will use chlorides, though again it's dependent on what you want in the end. Nickel sulfamate, for example, does not require chlorides if sulfur-bearing nickel is used. Basically, the short answer is that chlorides affect more than just how you get your ions.

Offline snorkack

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Re: Can electroplating be done with oxides instead of chlorides?
« Reply #16 on: February 13, 2014, 01:47:44 PM »
Oxides cannot be directly dissolved because O2- is a too heavily charged ion and converts to OH- in water.
Most soluble hydroxides - the alkali metal and alkaline earth metal ones - are of very active metals (potentials below -2,7 volts) that cannot be reduced (because hydrogen is reduced).

There is, however, one conspicuous exception. Thallium I hydroxide is a very soluble strong base, yet thallium metal is less active than iron - potential just -0,34.

By contrast, thallium chloride is insoluble.

Is metallic thallium easy to electroplate out of thallium hydroxide solution?

Offline eazye1334

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Re: Can electroplating be done with oxides instead of chlorides?
« Reply #17 on: February 13, 2014, 03:06:11 PM »
Thallium salts were once used as a gold plating bath additive to improve brightness, but outside of that, not a clue.

And like I said, cadmium oxide can be used as the metal source for a cadmium bath, with an alternative being cadmium cyanide.

Offline billnotgatez

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Re: Can electroplating be done with oxides instead of chlorides?
« Reply #18 on: February 13, 2014, 07:26:24 PM »
Just as an aside

WIKI states

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Cadmium cyanide is an inorganic compound with the formula Cd(CN)2. This white crystalline compound is used in electroplating.  It is very toxic, along with other cadmium and cyanide compounds.

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Soluble thallium salts (many of which are nearly tasteless) are highly toxic in quantity, and were historically used in rat poisons and insecticides.



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