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Author: Subject: Metal melting Charcoal furnace
neutrino
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[*] posted on 18-1-2005 at 14:22


Quote:
Originally posted by Cyrus
I'm guessing cool it down slowly


You anneal the glass, i.e. hold it at a temperature lower than its softening point for a while. This relieved internal stresses and makes the glass safe. The same thing goes with metals: annealing makes them softer. The best way to do this is with an annealing oven.
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[*] posted on 18-1-2005 at 17:17


Thanks neutrino. I have no annealing oven though. :( Shh, my glass won't be tempered.;)

Chemoleo, I'm pretty sure you can't just mix SiO2 and Al2O3 and fire them- well you could but It would be a powder coming into the furnace and a powder coming out. This is what I've found out at least at the temperatures I can attain. Now of course if you melt them, then they'll stick together, but either way, these things have NO strength in the green state, so I doubt they'd be practical.

You need a binder of some kind.

When the sites say 50% Al2O3, 25% SiO2, 25% ZrO, what they really mean is

25% ZrSiO4, 5% clay, 20%Al2O3, 50% mullite. Now I made these up, but the point still stands that it's hard to figure out what's in these crucibles- you can do some educated guessing though. For a link with all kinds of oxide analysis, see the link in the crucible thread to bartley crucibles. They have data for about every kind of crucible (not Zirconia though)

Hope this helps

Cyrus.




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