I want to melt a very small quantity of gold so I'm looking to make a.. well, call it a microcrucible. I want to avoid metal because I don't want the gold to bind to it. I have a graphite crucible, but it's much too large. I have some high-purity 0.5" carbon rod, and I'm wondering how it could be made to work. Say, if I take a one-inch length and make a well in it.

 

So, my questions:

 

1. How would the straight carbon react to open flame?
2. Is there a way to graphitise carbon rod at home?
3. Maybe I could use it to make a tiny induction furnace?

Anyone have any (constructive <grin>) comments or suggestions?

 

Thanks!

If it's really carbon (or graphite; some suppliers call graphite the purer carbon, others make no difference) it will not react to a flame. That's why graphite serves to build ovens.

 

For kites, model airplanes... carbon rods are made of carbon fibers in a polymer matrix. Transforming them into a carbon-carbon composite would be a too big effort. As the polymer is graphitized (under controlled atmosphere) it must be replenished with some tar-like material, normally done under vacuum. Hydrocarbon gases are also used.

 

Alumina powder is available commercially to make parts by mixing it with water, much like plaster. Make a crucible, try it at the proper temperature.

 

Maybe you find a concave stone in a river? Not recessarily the perfect shape, and it may break at heat.

 

An induction furnace must be feasible, if you have solid knowledge of electromagnetism, but that's a significant effort just to replace a blowtorch. You might take a used induction coker and redesign the magnetic parts.

I don't think it's graphite; it doesn't have the right cleavage. In fact, it doesn't appear to have any cleavage; I think it's truly amorphous carbon.

 

I just didn't know whether amorphous carbon was suitable for crucibles; I've only seen graphite ones.