SAM4CH
Hazard to Others
Posts: 162
Registered: 16-7-2004
Location: TA
Member Is Offline
Mood: PERFECT
|
|
Electroplating of Tungsten Carbide
How to plating Tungsten carbide using electrochemical technique?
My raw material is Tungsten carbide alloy which use in cutting tools in lathe!!
|
|
|
Eclectic
National Hazard
Posts: 899
Registered: 14-11-2004
Member Is Offline
Mood: Obsessive
|
|
Cheaper tungsten carbide grades (C2) are tungsten carbide particles in a metal matrix, mostly cobalt, 3-5%.
Maybe quick nitric acid etch followed by silver electroplate?
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
Tungsten carbide is conductive, isn't it? Etching the cobalt (or whatever) should give plenty of tooth for whatever process.
Tim
|
|
|
SAM4CH
Hazard to Others
Posts: 162
Registered: 16-7-2004
Location: TA
Member Is Offline
Mood: PERFECT
|
|
I tried with 15g NH4Cl dissolved in 145mL ammonium hydroxide and run electrolysis "anode=tungsen carbide tool, cathode= graphite", I noticed silver
plating on graphite but when I heatd the solution the layer disapeared, and I filter my solution after anode decrease about 20g of its origin weight,
I get a green solution and I seperate gray powder.. I tried to evaporate about third of origin volume, but I didn't get any precipitate..
Now.. what is the gray powder? Is it tungsten, cobalt, nickel!!
How to detect?
What about tungsten reaction? specification?!!
Tungsten plating with nickel to form heavy alloy?!!
I have pure tungsten rod! How to make sodium tungstate?
[Edited on by SAM4CH]
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
Whataf?
Dude, you said you wanted to know about PLATING the tungsten carbide.
Then you go on to say you made a basic ammonium chloride solution and ran your carbide as the ANODE? Metal doesn't deposit from an empty solution and
it certainly doesn't deposit on the anode!
If you wanted to DISSOLVE the stuff, and perhaps plate out tungsten or cobalt, that's different, and you should say so!
And lastly, since you DO appear to be interested in dissolving the stuff, why not read up on composition a bit, hmmm?! "Carbide" toolbits, these
days, are exclusively sintered material, not solid. The bonding agent is 5-20% cobalt.
Tungsten carbide, being what it is, is not going to react. You will get a solution (or plating out on the cathode) of cobalt, and tungsten carbide
sludge falling off the anode.
Tim
|
|
|
Eclectic
National Hazard
Posts: 899
Registered: 14-11-2004
Member Is Offline
Mood: Obsessive
|
|
If you use strong HCl, with the carbide as the anode, a good amount of the carbide will be oxidized to insoluble yellow tungstic acid.
|
|
|
SAM4CH
Hazard to Others
Posts: 162
Registered: 16-7-2004
Location: TA
Member Is Offline
Mood: PERFECT
|
|
Yeah, I did not want to plate from empty solution but I need to make pure tungsten salt first to make plating solution!!
If my grey powder still tungsten carbide how to test it? and how to make soluble salt of tungsten like sodium tungstate?
|
|
|
not_important
International Hazard
Posts: 3873
Registered: 21-7-2006
Member Is Offline
Mood: No Mood
|
|
It is not clear if you are trying to
A) Plate onto tungsten carbide, or
B) plate tungsten carbide onto something
B isn't going to happen, at least not with aqueous chemistry.
Tungsten metal can be plated out from fused salt mixtures, I believe a mix of sodium tungstate and carbonate but I don't have the book handy so no
promises on that.
Tungsten metal can be dissolved by
1) Fusion with NaNO3 + NaOH at 400 C, followed by dissolving in water
2) Treating the metal with H2O2. This is fairly slow for massive tungsten, and you have to keep adding more H2O2 as it is in part decomposed as well
as reacting.
3) Use the metal as anode with 4 N NaOH solution, and dissolve it electrolytically.
The tungsten carbides are fairly inert, and likely would best attacked with the fused NaNO3/NaOH mixture.
To test if the powder is tungsten carbide, you have hardness and density, and after that elemental analysis - a simple form would be heating some in a
stream of oxygen and testing the resulting gas for CO2, solid for tungsten (as WO3)
The powder could be cobalt, deposited as such from poor control of the voltage and current. It would dissolve in moderately acid, giving pale pink
solutions. Evaporate to near dryness, add enough water to dissolve, add NaOH dropwise to get Co(OH); when slowing adding hydroxide to the Co salt the
Co(OH)2 is usually blue, sometimes pink. Adding an excess of NaOH and warming will dissolve the ppt to give a blue solution. You can also do the
borax bead test for cobalt.
[Edited on 14-7-2007 by not_important]
|
|
|
SAM4CH
Hazard to Others
Posts: 162
Registered: 16-7-2004
Location: TA
Member Is Offline
Mood: PERFECT
|
|
I tried to dissolve Tungsten in H2O2 and it dissolved well but what happened? and how to prepare sodium tungtate!!
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
