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When I worked in a Foundry the crucible they used was made out of a steel pot. So I would use a steel or cast iron pot.
Steel 2500 to 2800 degrees f
Iron 2060 to 2360 degrees f
Aluminum 1218 degrees f
Steel or Cast Iron will get a little red but it will hold.
Theres an instructable i remember seeing for making crucibles. Here they are:
Ray74 made both of them.
army surplus store near me has stuff for gold panning. this includes little ceramic crucibles, about 3 inch dia. $3 to $6. gold melts hotter than Al, iirc. so Al should be ok in it.
You could get a copy of Vincent R. Gingery's Making Crucibles
Link doesn't seem to work...
Copy and paste the following link: http://www.amazon.com/Making-Crucibles-Vincent-R-Gingery/dp/1878087274/ref=pd_ys_sf_s_283155_b4_1_p?ie=UTF8&refRID=1235ZX257P6E8VEJ8SDK
Yep, that works, thanks. I've had issues with linking here too (especially two links in one paragraph).
RE: crucibles--I have five, from my father-in-law: two cast iron, three steel. Used, I think, for old-school lead plumbing packing (one still partly filled with lead). But I'd like to try casting Zamak alloy, and that's contaminated by iron...
I am trying to make a small size arc furnace mainly for aluminium.
Getting fire bricks here is a pain in the ....
Fire proof cement would be an option as it is rated for around 1000-1400° Celsius depending on the type of concrete.
Downside is that the firing temps often exeeds those limits.
To overcome this problem I am now seeking alternative building materials from the old days.
Clay I don't really like as, at least in my tests it tends to crack too easy.
Currently I have a new recipe curing:
Normal plaster mix with some extreme heat resistant additions to keep it together with changing temps as well as providing good insulation.
If any of the recipies turn out working fine I will make a short Instructable for it.
I just guess but if it survives a few thausand degrees in an arc furnace it should be good enough for crucible too, at least for low temp metals as aluminium.
Ok, forget the plaster mix.It does take quite much to get this mix to melt in the arc but it does expand too much under heat causing cracks to form.For a cheap alternative check your nearest refractory and get some light weight fire bricks.You can cut them with a knife or saw and they handle temp of up to 1200° celsius with no problem.An no, molten metal does not stick to it.
thanks for that idea. but how do i safely empty and cut them open
Posted:Mar 8, 2015
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