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View Full Version : Making your own Tungsten Carbide - Popular Science column



hornluv
01-13-2009, 11:37 AM
Popular Science has a column every month called Gray Matter, relating to chemistry. The latest installment is about making your own Tungsten Carbide, which the column acknowledges is highly impractical. Anyway, after a bit of research, the author, Theodore Gray, figures out how to do it by mixing powdered TC and cobalt and heating it up. He made a little disc of it and brazed it onto a steel shank and actually turned a bit of aluminum on his lathe. Pretty neat, although, he didn't leave much support under the carbide, so I can't see it lasting terribly long. Anyway, if you get a chance, check out the article. It really was pretty interesting.

tony ennis
01-13-2009, 01:01 PM
Neat idea. While it may not be practical to make your own in the general case, every now and then there could be that one thing you need you can't get anywhere else - except to make it yourself.

lazlo
01-13-2009, 01:14 PM
Neat project, but Tungsten has the highest melting point of any elemental metal: 6192 F (which is why it's used for TIG electrodes).

How the heck did he make a 6,000 oven?

The Doctor
01-13-2009, 01:18 PM
He wouldn't need to make a 6000 oven. You don't melt the tungsten, you melt the cobalt binder, which locks all the tungsten particles together. Cobalt melts at 2723 F, which is much easier to achieve. http://en.wikipedia.org/wiki/Cobalt

Ed

lazlo
01-13-2009, 01:19 PM
Ah, good point -- it's not an alloy, it's sintered.


Cobalt melts at 2723 F

When you're sintering, you don't melt the carrier metal either -- you just have to get it plastic. But that means he had to make a press where the
chamber temperature was, say ~ 2,000 F. That's a pretty amazing feat!

Edit: according to Wikipedia, unlike most sintering processes, tungsten carbide is "liquid sintered", meaning that the carrier metal is melted, and I gather there's no pressure required.

"A special form of sintering, still considered part of powder metallurgy, is liquid state sintering. In liquid state sintering, at least one but not all elements are in a liquid state. Liquid state sintering is required for making cemented carbides or tungsten carbide."

So how the heck did he make a 3,000 oven? :D

I'm not a big fan of Popular Science, but that article is probably worth the newsstand cost :)

dan s
01-13-2009, 01:32 PM
Neat project, but Tungsten has the highest melting point of any elemental metal: 6192 F (which is why it's used for TIG electrodes).

How the heck did he make a 6,000 oven?


http://www.theodoregray.com/PeriodicTable/Samples/074.59/index.qt.s12.html

lazlo
01-13-2009, 01:35 PM
http://www.theodoregray.com/PeriodicTable/Samples/074.59/index.qt.s12.html

Thanks Dan! Saved me $4:)

"I used an acetylene torch and a graphite mold to sinter together tungsten carbide and cobalt powder (cobalt is the binder that holds together the very hard particles of tungsten carbide). Then I ground and sharpened the resulting pellet on a diamond wheel and silver soldered it to a steel shank."

dan s
01-13-2009, 01:59 PM
Thanks Dan! Saved me $4:) NP, you might like this page as well :D

http://www.popsci.com/graymatter

hornluv
01-13-2009, 02:22 PM
http://www.theodoregray.com/PeriodicTable/Samples/074.59/index.qt.s12.html

Yep. That's the tool bit he made. See what I mean about the lack of support for the carbide? In making the TC disc, he used a piece of graphite as a crucible and heated the Tungsten and Cobalt with a rosebud tip on an O/A torch. No oven or press used.

lazlo
01-13-2009, 04:13 PM
NP, you might like this page as well :D

http://www.popsci.com/graymatter

Wow, thanks for that Dan! He does some seriously cool projects!

That'll take a good afternoon to read through all his experiments :)

mochinist
01-13-2009, 07:15 PM
That popsci.com site is pretty damn cool, thanks