Thermite "bricks"
Hon1nbo, Mon Feb 03 2014, 10:41PMAll,
I have been trying to make a Thermite "brick." I don't like measuring raw powder every time I destroy a drive or cast some metal, so I'd like to make some standard size cubes or similar of thermite.
So far I have looked at some various recipes online, most of which involve plaster of paris. I tried a plaster cube, and I could not for the life of me get the cube of thermite to ignite, even with powdered thermite burning on top of it!
I'm thinking that the various binders are preventing an interaction between the iron oxide and aluminum powder.
Does anyone here have some suggestions for making a solid piece of thermite? Are there any binders that won't prevent the oxidation of the aluminum at a reasonable (relative to normal thermite) starting temperature?
-Jimmy
Re: Thermite "bricks"
Shrad, Tue Feb 04 2014, 06:47AM
parafin
I'd wet the mix with liquid paraffin and stirr till it has the consistency of a paste (inside a bowl placed in a container with very hot water so it doesn't solidify, like you'd do with rocket fuel but at a lower temperature)
Shrad, Tue Feb 04 2014, 06:47AM
parafin
I'd wet the mix with liquid paraffin and stirr till it has the consistency of a paste (inside a bowl placed in a container with very hot water so it doesn't solidify, like you'd do with rocket fuel but at a lower temperature)
Re: Thermite "bricks"
Sulaiman, Tue Feb 04 2014, 01:13PM
I've never played with thermite but Chemistry used to be a hobby of mine,
I would think that ready-mixed thermite has a risk of spontaneous combustion if moist/damp, which could be disasterous.
Sulaiman, Tue Feb 04 2014, 01:13PM
I've never played with thermite but Chemistry used to be a hobby of mine,
I would think that ready-mixed thermite has a risk of spontaneous combustion if moist/damp, which could be disasterous.
Re: Thermite "bricks"
Shrad, Tue Feb 04 2014, 04:00PM
hence paraffin, and a poper mix with glycerin or something might event make it plastic
Shrad, Tue Feb 04 2014, 04:00PM
hence paraffin, and a poper mix with glycerin or something might event make it plastic
Re: Thermite "bricks"
Wastrel, Tue Feb 04 2014, 05:53PM
Anything that produces volatiles is going to be a problem. I would bake the oxide, mix when cool and portion into heat seal mylar bags. They will have a lifespan, but then all aluminium powder goes bad eventually.
Wastrel, Tue Feb 04 2014, 05:53PM
Anything that produces volatiles is going to be a problem. I would bake the oxide, mix when cool and portion into heat seal mylar bags. They will have a lifespan, but then all aluminium powder goes bad eventually.
Re: Thermite "bricks"
Hon1nbo, Wed Feb 05 2014, 06:22PM
Well, I tend to use coarser powders that require more ignition resources, though admittedly I did try some finer powder for this when the first batch failed. Nice thing about standard thermite is that unless you have ultra-fine powder it is very hard to light, which makes it relatively safe to handle (key word relatively).
I have never heard of it being more dangerous damp except when actually burning at which point it is practically explosive, but I always treat my thermite reactions like they might explode after a rock that was obscured under a batch fractured violently and caused a serious problem. Also, by the time I intend to light these they will have been dried out.
Is there a particular effect on standard thermite when wet that occurs when not already under ignition conditions?
@Shrad
I might have to try paraffin in my next batch.
@Wastrel
As for baking, I'm not sure how that would work. Does the oxide exhibit some kind of cohesive properties when heated? would it stay intact when cooled? Now that you mention mylar bags I could use a bag that evaporated off.
-Jimmy
Hon1nbo, Wed Feb 05 2014, 06:22PM
Sulaiman wrote ...
I've never played with thermite but Chemistry used to be a hobby of mine,
I would think that ready-mixed thermite has a risk of spontaneous combustion if moist/damp, which could be disasterous.
I've never played with thermite but Chemistry used to be a hobby of mine,
I would think that ready-mixed thermite has a risk of spontaneous combustion if moist/damp, which could be disasterous.
Well, I tend to use coarser powders that require more ignition resources, though admittedly I did try some finer powder for this when the first batch failed. Nice thing about standard thermite is that unless you have ultra-fine powder it is very hard to light, which makes it relatively safe to handle (key word relatively).
I have never heard of it being more dangerous damp except when actually burning at which point it is practically explosive, but I always treat my thermite reactions like they might explode after a rock that was obscured under a batch fractured violently and caused a serious problem. Also, by the time I intend to light these they will have been dried out.
Is there a particular effect on standard thermite when wet that occurs when not already under ignition conditions?
@Shrad
I might have to try paraffin in my next batch.
@Wastrel
As for baking, I'm not sure how that would work. Does the oxide exhibit some kind of cohesive properties when heated? would it stay intact when cooled? Now that you mention mylar bags I could use a bag that evaporated off.
-Jimmy
Re: Thermite "bricks"
Sulaiman, Wed Feb 05 2014, 08:27PM
What kind of bag wouldn't evaporate off with thermite ?
I have no specific. info. on thermite/damp, just that air+moisture = electrolyte between reactive molecules.
Sulaiman, Wed Feb 05 2014, 08:27PM
What kind of bag wouldn't evaporate off with thermite ?
I have no specific. info. on thermite/damp, just that air+moisture = electrolyte between reactive molecules.
Re: Thermite "bricks"
Wastrel, Wed Feb 05 2014, 08:35PM
Baking just to dehydrate the oxide. I understand volatiles make the reaction badly behaved.
Wastrel, Wed Feb 05 2014, 08:35PM
Baking just to dehydrate the oxide. I understand volatiles make the reaction badly behaved.
Re: Thermite "bricks"
Shrad, Wed Feb 05 2014, 09:17PM
baking can be the starting point for dropping some paraffin and gently stir till it becomes pasty, then mold in some yoghurt pots or something...
Shrad, Wed Feb 05 2014, 09:17PM
baking can be the starting point for dropping some paraffin and gently stir till it becomes pasty, then mold in some yoghurt pots or something...
Re: Thermite "bricks"
radiotech, Mon Feb 17 2014, 09:20PM
I don't know why you want a brick of Thermite, so I am assuming is it to hold or mold a charge
to a task.
I used to construct copper ground networks out of 000 GA bare stranded wire.
The powder was poured into graphite molds which came in various shapes , X, T, Join,
or Face Bond (to weld the wire onto an iron surface)
The blocks were about 3 x 3 x 7 inch, had a handle, and a hole in the top to ignite.
radiotech, Mon Feb 17 2014, 09:20PM
I don't know why you want a brick of Thermite, so I am assuming is it to hold or mold a charge
to a task.
I used to construct copper ground networks out of 000 GA bare stranded wire.
The powder was poured into graphite molds which came in various shapes , X, T, Join,
or Face Bond (to weld the wire onto an iron surface)
The blocks were about 3 x 3 x 7 inch, had a handle, and a hole in the top to ignite.
Re: Thermite "bricks"
2Spoons, Thu Feb 20 2014, 04:48AM
From a long thread on thermites:
2Spoons, Thu Feb 20 2014, 04:48AM
From a long thread on thermites:
"Recent explorations: Plaster of Paris (CaSO4:H2O + Al)
I thought this worth writing down (although I am sure many have done this, it's just for the record :))
Plaster of Paris (CaSO4*1H2O) was mixed with Al in stoichiometric quantities (IIRC 1kg of PoP and 270 g or so of Al), and mixed with H2O, to form the normal gypsum kind of plaster. This was dehydrated at 200 deg C in the oven for 3+ hours; basically until the weight didn't drop any further (guidelines are hard to give as dehydration depends on the diameter of the piece). It's remarkable how much weight you lose.
A small piece failed to ignite from a normal lighter flame. HOWEVER, a bit larger piece DID ignite once a drill was applied to it (holes were drilled for the sparklers to fit into). So that is a NO NO!
Nonetheless, this type of thermite works extremely well, it burns intially slow, but once it gets going, it produces a massive amount of gas (SO2)/smoke, and produces a lot of sparks. Very pretty :). Perfect for certain occasions.
The fact that the drill was able to set off the Plaster/Al mix showed it is somewhat sensitive - so in the future it probably is better to do this by simply mixing the powders (and igniting the mix without adding water), or by adding a very tiny amount of water just to solidify it.
"
Re: Thermite "bricks"
Tetris, Tue Feb 25 2014, 12:24AM
Hmm, I wonder if some form of wax could do it. Or maybe you could make some sort of putty out of talcum powder and mix it into that.
Tetris, Tue Feb 25 2014, 12:24AM
Hmm, I wonder if some form of wax could do it. Or maybe you could make some sort of putty out of talcum powder and mix it into that.
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