Re: [hobbicast] Materials needed for a Ceramic Crucible
- In a message dated 11/6/2009 2:03:09 PM Mountain Standard Time,
My friends and I want to try melting steel in our furnace, but we need a
crucible that can withstand the heat. We are going to have my aunt use her
kiln and attempt to make one for us.
We have the fireclay, we just need to know what else is required to make
the crucible. Suggested materials would be appreciated.
One of the problems you will face is that at the temperatures that steel
melts, most refractories lose strength, and lose the charge out the bottom.
If you study the characteristics of refractories, you find that they have a
heat transmission value, depending on what and how they are made. The trick
is to get a crucible lining that will stand up to the temperatures, and
surround it with an insulating refractory that slows down the heat transfer
through it, and encase it in a steel outer cover that will dissipate the heat
that does get through, and will maintain its strength while at the
temperature that that results at the outer cover.
This requires heat application to the inside of the melt, as in a copula or
electric arc furnace.
So I don't think a home fired crucible will do what you want.
I could be wrong, so if you do get it to work, there are a number of people
on this board that would like to hear about it. Let us know how it turns
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- Hi There,
Let me give you my short answer first-----don't even think about it!!! I am curious about what type of furnace you plan to use. Does it reach a temperature of around 2500 degrees F? I really cringe when I read about all the things people use as melting vessels. Cast iron lead melting pots, stainless steel cookware, pipe nipples, and even steel soup cans. Those will certainly work for melting aluminum or lead/tin alloys, but even then, you are running a great risk for failure. Molten aluminum is extremely corrosive and will dissolve steel and iron.
Does your aunt have all the required skills and experience to produce a quality controlled crucible? The pros who manufacture real crucibles do, and they have failures. Crucibles have a set of rules which must be followed religiously to prevent failures, preconditioning before the initial use, ringing tests to determine soundness, no storage in damp places, etc., etc. Suppose you do manage to make a crucible which will withstand the very high temperature to melt steel. Does it also have the physical strength to withstand the pressure of the lifting tongs.
I hate the price I have to pay to buy good commercial crucibles, but I just weigh the risks and happily fork over my cash. If you do manage to melt steel in some kind of home-brew crucible. Are you willing to gamble the loss of a foot, or a leg? How about six months in the intensive care unit of a burn ward? Yes, people have been making their own crucibles for thousands of years. Those people were real artists and were probably held in high regard by their various tribes etc. What we don't know though, is how many of them ended up dead due to a crucible failure. "Sorry Lars, but you won't be able to join us for raping, pillaging, and plundering today, because the wheelchair hasn't been invented yet. You will just have to stay here and guard the boat".
I am an avid do-it-yourselfer, and I really don't care for the self appointed safety nannies who cry , "danger" about every little thing. Trust me, this is no , "little thing". I hope you reconsider.
--- In email@example.com, "dmnelson88" <dmnelson88@...> wrote:
> My friends and I want to try melting steel in our furnace, but we need a crucible that can withstand the heat. We are going to have my aunt use her kiln and attempt to make one for us.
> We have the fireclay, we just need to know what else is required to make the crucible. Suggested materials would be appreciated.
- On Nov 6, 2009, at 7:44 PM, scobeyguy wrote:
> I am an avid do-it-yourselfer, and I really don't care for the selfIn case any of you are wondering what the difference between "self
> appointed safety nannies who cry , "danger" about every little
> thing. Trust me, this is no , "little thing". I hope you reconsider.
appointed safety nannies" and sensible safety suggestions might be;
any safety suggestions that I make (such as a noob casting steel or
danger of breathing zinc fumes) qualify as "crying danger" , whereas
Gary suggestions clearly do not.
Just thought I would clear that up.
Jeshua Lacock, Owner