Electroplating from tungsten via phosphate salt?

In summary, Tungsten is highly resistant to diluted phosphoric acid but dissolves easily in concentrated acid. Its reaction with phosphoric acid results in W(PO4)2 due to its multiple oxidation states. However, there is limited information on tungsten compounds and their suitability for electroplating. Additionally, tungsten forms a metal/metal oxide/metal ion system in aqueous solutions, making it difficult to use in electroplating.
  • #1
jrodatus
11
0
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.

I'm presuming the reaction goes something like 2H[itex]_{3}[/itex]PO[itex]_{4}[/itex] + 2W → 3H[itex]_{2}[/itex] + 2WPO[itex]_{4}[/itex]

Since I'm pretty sure copper phosphate works just fine for electroplating, why wouldn't tungsten phosphate? What's the difference? 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!
 
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  • #2
I think the result is more like W(PO4)2, since phosphate is -3 while W can be +6. Since tungsten has several oxidation states running from +6 to -2, there may be different compositions.
 
  • #3
SteamKing said:
I think the result is more like W(PO4)2, since phosphate is -3 while W can be +6. Since tungsten has several oxidation states running from +6 to -2, there may be different compositions.

Okay, assuming W loses all 6 electrons like it can, that sounds like a pretty strong bond. I suppose it would be insoluble in pretty much anything. Thank you.
 
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  • #4
Sections 3.7 and 3.8 of your reference also discuss some aspects of electroplating with tungsten. Apparently, not much is known about tungsten compounds and this lack of information makes it difficult to determine which compounds are the most suitable.
 
  • #5
SteamKing said:
Sections 3.7 and 3.8 of your reference also discuss some aspects of electroplating with tungsten.

Doh, thank you again. From page 123:

In aqueous solution, no oxygen-free tungsten cation exists but only monomeric or dimeric species like WO[itex]^{2+}_{2}[/itex]. Tungsten, due to its great affinity to oxygen, may never form a metal/metal ion electrode system but always a metal/metal oxide/metal ion system, which is quite irreversible.

(Just posting it here for reference. Hope that's not a copyright violation.)
 
  • #6
Nope. You aren't claiming the work is your own, and it falls under what is known as 'fair use'.
 

1. What is electroplating from tungsten via phosphate salt?

Electroplating from tungsten via phosphate salt is a process in which a thin layer of tungsten is deposited onto a surface using an electric current and a solution containing phosphate salt. This method is often used to enhance the properties of a surface, such as increasing its hardness or resistance to corrosion.

2. How does electroplating from tungsten via phosphate salt work?

During the electroplating process, the surface to be plated is connected to the negative terminal of a power source, while a tungsten anode is connected to the positive terminal. The solution containing phosphate salt acts as an electrolyte, allowing ions from the tungsten anode to be deposited onto the surface, forming a thin layer of tungsten.

3. What are the benefits of electroplating from tungsten via phosphate salt?

Electroplating from tungsten via phosphate salt can provide several benefits, such as improving the surface's hardness, wear resistance, and corrosion resistance. It can also improve the surface's appearance and provide a more uniform coating compared to other plating methods.

4. What surfaces can be electroplated using tungsten via phosphate salt?

Tungsten electroplating via phosphate salt can be applied to a wide range of surfaces, including metals, plastics, and ceramics. However, the surface must be conductive to allow the electric current to pass through it and facilitate the plating process.

5. Are there any safety precautions to consider when electroplating from tungsten via phosphate salt?

Yes, there are some safety precautions to consider when electroplating from tungsten via phosphate salt. The solution used in the plating process may contain hazardous chemicals, so proper safety equipment, such as gloves and goggles, should be worn. It is also essential to follow the manufacturer's instructions and work in a well-ventilated area to avoid inhaling any fumes. Additionally, the power source should be turned off when not in use to prevent electrical hazards.

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