casting and welding are two fundemental area's. If you can do one of these, you can make parts for your other experiments. its really handy.
ok, crash course. If you see people using metal for crucibles, they probably are not that good of a resource. This implys that they know nothing about chemistry or metal. but that might be ok if your starting.
(There are exceptions, but I am assuming most DIYers will choose a cheaper ceramic over expensive super alloys, to ruin with casting, which also require TIG-E to weld properly. Aluminum will pull iron into solution, even if its stainless steel. it will just rob the iron right out of the lattice. So you end up with a damaged crucible, and an iron - alluminum series of intermetallic compounds, which makes the Al more brittle. )
expensive Alumina crucibles work, but more commonly, graphite+binder crucibles are used. Pure graphite would would great, if it was far enough away from the burner, as it would react with the hot oxygen. The binder protects the carbon as well as holding it all together. Cement would not be a very good crucible for 2 big reasons... 1. if any moisture or air gaps were formed while setting up, heating it would make those pockets expand and fracture the structure. or more likely, pop the thing apart. 2. cement is a pretty good insulator. You want a material that will A. not melt. B. not react with the stuff inside or outside. C. allow some heat to pass through it. D. insulate the hot metal. E. hold together enough, that you can pick it up with whatever, while holding molten metal. (and pour it). Failure to do the last part, would result in some serious burns, or damaged equipment.
I am sure in a place your in, you might find it easier to get ahold of a small graphite crucible. Foundries are more common in developing area's. (not to suggest you live in a developing area or anything).
I used propane, but really, you can just check out a table of organic fuels in a chemistry book, to see what kind of heat you can get. just note that a lot of the energy produced by the initial combustion, is used in a 2nd reaction around the inner envelope, converting a lot of the CO and H2 into CO2 and H2O. If you can find a book on ebay or something, called the Combustion Handbook, grab it. its full of really good stuff. (even if its 50 years old). you could even use solid fuel... (coal, coke, charcoal, pure graphite (expensive), or whatever.
The blower is there, to ram air into the middle of the combustion. Suppose you just lit a burner with fuel and stuck it into the bottom of the furnace. After a few min, the flame would either go out, or start burning greenish, since you are suffocating the combustion. (you need Oxygen to complete the chemistry, for max exothermic reaction to take place)
So, the blower rams N2 and O2 into a mixing chamber, which is ejected out into another area, where the velocity comes down a little. The N2 is ignored because O2 is more reactive. The slow in velocity of the air/fuel gas allows the combustion to burn up the gas at the same rate the gas is feeding the combustion. Too much velocity and the flame will go out. too little and it can flash back inside the burner... or possibly the fuel line/tank. (iv never had it go back into the tank, but im not sure if it would explode or not. if there is no oxygen, nothing would happen. if oxygen was sucked in with it, there would be a problem.)
anyway! you could do your storm idea, with multiple burners/blowers. I know of at least 1 person who does 2 burners around a circle, to make an awsome spiral that heats evenly. the one that I made recently, just has one burner, but still spirals around heating the crucble in a gradient fashion.
you can design the thing anyway you want, just remember the main point is... to get maxium heat distrobution into that metal your trying to melt. 1 burner or 10 burners, if the net enthalpy is the about the same, it doesnt matter. in fact you could, in theory, use a candle to melt metal, if oxygen was supplied, and there was enough insulation.
ok, crash course. If you see people using metal for crucibles, they probably are not that good of a resource.
This implys that they know nothing about chemistry or metal. but that might be ok if your starting.
(There are exceptions, but I am assuming most DIYers will choose a cheaper ceramic over expensive super alloys, to ruin with casting, which also require TIG-E to weld properly. Aluminum will pull iron into solution, even if its stainless steel. it will just rob the iron right out of the lattice. So you end up with a damaged crucible, and an iron - alluminum series of intermetallic compounds, which makes the Al more brittle. )
expensive Alumina crucibles work, but more commonly, graphite+binder crucibles are used. Pure graphite would would great, if it was far enough away from the burner, as it would react with the hot oxygen. The binder protects the carbon as well as holding it all together.
Cement would not be a very good crucible for 2 big reasons... 1. if any moisture or air gaps were formed while setting up, heating it would make those pockets expand and fracture the structure. or more likely, pop the thing apart. 2. cement is a pretty good insulator. You want a material that will A. not melt. B. not react with the stuff inside or outside. C. allow some heat to pass through it. D. insulate the hot metal. E. hold together enough, that you can pick it up with whatever, while holding molten metal. (and pour it). Failure to do the last part, would result in some serious burns, or damaged equipment.
I am sure in a place your in, you might find it easier to get ahold of a small graphite crucible. Foundries are more common in developing area's. (not to suggest you live in a developing area or anything).
I used propane, but really, you can just check out a table of organic fuels in a chemistry book, to see what kind of heat you can get. just note that a lot of the energy produced by the initial combustion, is used in a 2nd reaction around the inner envelope, converting a lot of the CO and H2 into CO2 and H2O. If you can find a book on ebay or something, called the Combustion Handbook, grab it. its full of really good stuff. (even if its 50 years old). you could even use solid fuel... (coal, coke, charcoal, pure graphite (expensive), or whatever.
The blower is there, to ram air into the middle of the combustion. Suppose you just lit a burner with fuel and stuck it into the bottom of the furnace. After a few min, the flame would either go out, or start burning greenish, since you are suffocating the combustion. (you need Oxygen to complete the chemistry, for max exothermic reaction to take place)
So, the blower rams N2 and O2 into a mixing chamber, which is ejected out into another area, where the velocity comes down a little. The N2 is ignored because O2 is more reactive. The slow in velocity of the air/fuel gas allows the combustion to burn up the gas at the same rate the gas is feeding the combustion. Too much velocity and the flame will go out. too little and it can flash back inside the burner... or possibly the fuel line/tank. (iv never had it go back into the tank, but im not sure if it would explode or not. if there is no oxygen, nothing would happen. if oxygen was sucked in with it, there would be a problem.)
anyway! you could do your storm idea, with multiple burners/blowers. I know of at least 1 person who does 2 burners around a circle, to make an awsome spiral that heats evenly. the one that I made recently, just has one burner, but still spirals around heating the crucble in a gradient fashion.
you can design the thing anyway you want, just remember the main point is... to get maxium heat distrobution into that metal your trying to melt. 1 burner or 10 burners, if the net enthalpy is the about the same, it doesnt matter. in fact you could, in theory, use a candle to melt metal, if oxygen was supplied, and there was enough insulation.
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