I have clay graphite (typical foundry type) and pure graphite (straight wall, grooved for tongs) crucibles. I burn through the graphite crucibles constantly. It really adds up in cost. I have never used up any of my clay-graphite crucibles, but even my smallest does not fit in my electric furnace. Does anyone make a cylindrical clay graphite crucible with a flange I can use in my electric furnace? Or any other material than pure graphite? Any reason they don't? The only downside I can think of is glass-weepage but my electric furnace is already beat to hell so that wouldn't bother me. Recently had a pure graphite crucible break inside the furnace spilling 2lb of bronze inside the chamber, and another almost broke during pouring. I do not trust these designs.
2.5" diameter x 6.5" height I can remove the ceramic top exposing the raw chamber which is 3 3/8" diameter by 5.5"
There may be some lab supply company with crucibles you can buy in that size. There's many refractory materials too: silicon carbide, sintered magnesium oxide and so on, it all depends on your budget. These guys have a 2 inch by 4 inch cylindrical aluminium oxide crucible for $25.95 but with no lip on the rim so you'll have to come up with a way to lift it out. https://www.msesupplies.com/collect...-cylindrical-crucibles?variant=32178920128570
Isn't fireclay made by firing clay powder in a furnace?. This crucible manufacturer in India is just using a clay and graphite mix fired for three days and then glazing the crucible. A good glaze seems to extend life by sealing the crucible surface from air.
Yeah pretty much. There are other ingredients but that's the basic idea. The fireclay I have is already a pretty good formula, so I won't be adding much to it. When I tested various compositions a while back the stock clay without any adjustment performed the best, though perlite made the samples much lighter.
These cylindrical crucibles for electric furnaces wear quickly. I have one and used it only two times in my electric furnace 1000 C and it oxidized considerably. Now I use just the 'standard' clay graphite crucibles in my electric Kanthal furnace just like in my propane furnace. Much better.
I read about an easy way to remove a crucible that is formed around a tapered mold.. That bit of info is gone now but it was as simple as coating the mold with beeswax.. At the right leather hard stage, it's heated enough to melt the beeswax and slip free.
You could form the crucible around a wax coated drinking glass the right size. Time to remove the glass pour hot water in the glass to melt the wax..
