[jrodatus]

At the bottom of page 54 of Tungsten: Properties, Chemistry, Technology of the Elements, Alloys, and Chemical Compounds by Lassner and Schubert:

Phosphoric acid (H3PO4): Tungsten is highly resistant to diluted phosphoric acid as long as air is excluded. It dissolves easily in concentrated acid. (emphasis added)

http://tinyurl.com/l6ysjp4

I'm presuming the reaction goes something like 2H₃PO₄ + 2W → 3H₂ + 2WPO₄. Since I'm pretty sure copper phosphate works just fine for electroplating, why wouldn't tungsten phosphate? The absence of any Google info on this makes me think there must be some good reason why it won't work.

But it sure would be useful for a particular project. Would appreciate input!

[jrodatus]

Okay, I think I understand why it doesn't work. The oxidation state of PO₄ is -3, while W can lose up to 6 electrons. So the salt would probably be W(PO₄)2, which seems like a pretty strong bond... probably insoluble in anything.

[eazye1334]

While I'm not sure of the exact reason why it won't work and I've never really looked into it, I do know that you cannot plate tungsten from an aqueous solution. It can be plated from a molten salt from what I have read, but the issues with performing that are fairly obvious.