stug161 Posted September 14, 2009 Posted September 14, 2009 Ya. So I mixed up ten grams of thermite. Layed it out on a 2X4 and lit it. It burned real fast with a few sparks. Left a few molten drops on the board, and blackened it, but just barely on the surface. So I mixed up 25 grams. Put it in one big pile, and it was a bit more impressive, maybe a bigger fire ball. It too left glowing medal behind, but just started to actually burn the board. I was kind of expecting a huge fire core, and the board to be burnt through. Maybe I am just too addicted to Mythbusters.. I used dark aluminum. Maybe I should try it with my -1200, or I have atom spher -325 Guess my plans to burn through a junk 350 block are a no go.. Robert
Ventsi Posted September 14, 2009 Posted September 14, 2009 For us pyros its a big waste of Al. You'll need quite a bit of Thermite to melt trough anything. Though most people use either spherical or granular -325 mesh. You're going to need something to get it started though.
Skycastlefish Posted September 14, 2009 Posted September 14, 2009 I've found that both Fe2O3 and Fe3O4 don't produce the same effect that some books and websites claim. Although it is a bit of a bummer, I have to admit, I don't really need to destroy metal objects in my day to day life. I too have found that -325 mesh ($20 for 5 lbs!) works just fine if you want to save a few bucks. I really like thermite, regardless of its true power!!!
Twotails Posted September 14, 2009 Posted September 14, 2009 Im going to try to cast some stuff out of it this winter, maby a small blade for a knife, it would be intersing to know i forged it. ( i often do metalwork in my sculptures, so hmm, i just have to see where this leads...)
KruseMissile Posted September 14, 2009 Posted September 14, 2009 its not going to burn through a 2x4(wood). Wood can take in alot more heat that metals... thats why it wont melt/burn through it.
NightHawkInLight Posted September 14, 2009 Posted September 14, 2009 its not going to burn through a 2x4(wood). Wood can take in alot more heat that metals... thats why it wont melt/burn through it.Got to it before I did. Yes, just because wood burns at a lower temperature than metal does not mean it is more susceptible to heat. Wood is a very good insulator. Once the top chars, unless there is excess oxygen to react with, it's not going anywhere. Carbon does not sublime until 3642 °C. Iron melts at a mere 1538 °C, and even boils nearly 1,000 degrees before carbon would even start to sublime. Thermite is not nearly hot enough for wood, though it is plenty hot to melt most metals. You will not burn a hole through a piece of wood with heat alone, It takes oxygen.
Mumbles Posted September 14, 2009 Posted September 14, 2009 If you want to produce any sort of localized heat, you'll need to slow the thermite way down. In high school we were able to melt partially through a cast iron pan. The Al was quite granular, 50 mesh or so. If you vaporize the iron, it can't sit there and burn through the wood/metal.
FrankRizzo Posted September 14, 2009 Posted September 14, 2009 The geometry of the assembly is very important. You need to load the mixture into a cylindrical casing that's resistant to the heat ( a small terra cotta pot works great), then use a stick to make a core down the center of the mix which terminates in a vent hole at the bottom of the container. This center cavity is very important as it channels the molten iron produced. Cover the vent hole before loading in the mixture with something easily burnt-through such as a thickness or two of paper. Then, the container has to be placed slightly above the intended target before ignition. Ignite in the core if possible. Don't expect it to able to penetrate wooden targets, as Nighthawk said. You should have no problem however penetrating sheet metal.
Ventsi Posted September 14, 2009 Posted September 14, 2009 Just wondering, what is the minimal amount that thermite can be successfully used in? 30g. , 50 or a 100?I tried it once using~ 10g and it didn't work at all, a few sparkles but no ignition.
TrueBluePyro Posted September 14, 2009 Posted September 14, 2009 This scientist guy I know has a ton bag of iron oxide and a drum of granular aluminium and when I was first interested in pyrotechnics he just dug out a hole in the dirt and got a few scoped of iron and Al and just mixed it and threw it in the dirt hole and it was pretty cool. All this molten metal just boiling around and jumping up. we put some metal rods into the molten red hot metal and they would melt off
psyco_1322 Posted September 14, 2009 Posted September 14, 2009 Just wondering, what is the minimal amount that thermite can be successfully used in? 30g. , 50 or a 100?I tried it once using~ 10g and it didn't work at all, a few sparkles but no ignition. Used for what? You can burn through Al foil with a gram...or blow it to pieces if you want. It could takes pounds to melt through something decent sized. Maybe your thermite sucks. I've seen two rusty balls slammed together with a sheet of Al foil in between and the energy released was enough to initiate a thermite reaction for a split second...so milligrams in that case.
Ralph Posted September 20, 2009 Posted September 20, 2009 try using very coarse aluminium less than 50 mesh hadnt made thermite in ages read this thread decided to try it with some granular aluminium and shaped it and out came a huge puddle of iron did the same but with 400mesh sheerical it hardly produced any iron finely managing to put a small dent in my red iron oxide supply
asilentbob Posted September 20, 2009 Posted September 20, 2009 As other posters have mentioned. You need course aluminum... It will be harder to get the mix going than if it was the fine stuff... but it will actually give a good puddle of molten iron instead of little pea sized chunks that the fine aluminum mix will give.
Ventsi Posted September 20, 2009 Posted September 20, 2009 Ahh, I see. Thanks for that. I had been using -325 Bright flakes.
stug161 Posted September 21, 2009 Author Posted September 21, 2009 I know my fine Al thermite was ignited super easy using a 3/1 mix with Mg/Al -600 I started it with a D1 glitter star. I would imagine it would be plenty hot enough to start coarse Al thermite. I have no Al courser than -325 Thanks for all the great information everyone!!
k9sports Posted October 16, 2009 Posted October 16, 2009 Sorry, can't start a new topic, something horribly wrong with your forums. Questions: How much thermite do I need to melt through an engine block? How big of a whole should ceramic garden pot that contains thermite be? Will a medium burn Chinese fuse (this one http://www.pyrocreations.com/inc/sdetail/79624) ignite Mg wire? I need something to ignite the magnesium with a delay, because I want to be at safe distance and film the thing go off. Another question, what's my mixture ratio should be for maximum effect on the engine block? I'm using ~350 mesh AL, and red F203? Does mixture ratio affect burn rate and burn temperature?
FrankRizzo Posted October 16, 2009 Posted October 16, 2009 (edited) Sorry, can't start a new topic, something horribly wrong with your forums. Sounds like something horribly *RIGHT* to me. You will not be able to melt through an engine block with thermite...that claim is highly overrated. However, you will be able to melt/distort the block such that the car will no longer run. If you want to cut through an engine block, a saw would be a much better tool. Edited October 16, 2009 by FrankRizzo
Mumbles Posted October 16, 2009 Posted October 16, 2009 Something is horribly right actually. You can't start a thread without a single post, but at least found a related thread. Anyway, you can't burn through an engine block with and reasonable quantity of thermite. It's an urban legend propagated by the anarchist cookbook and the like. The hole in the clay pot does matter at all. Yes the mixture affects the heat and burn speed. You can't make a cake with equal parts flour and sugar. Something is horribly right actually. You can't start a thread without a single post, but at least found a related thread. Anyway, you can't burn through an engine block with and reasonable quantity of thermite. It's an urban legend propagated by the anarchist cookbook and the like. The hole in the clay pot does matter at all. Yes the mixture affects the heat and burn speed. You can't make a cake with equal parts flour and sugar.
RUUUUUN Posted October 16, 2009 Posted October 16, 2009 ....... ..... .... ... This is very disturbing... First of all; most people frown on questions of: "How much of XX is required to vandalize/destroy YY object?" Second; If you knew the mass required and had an inkling of the density it would be very easy to calculate the volume required to hold said mass. The forum is designed to keep people without posts from making new threads, it keeps out spambots. The very popular idea that one little pot of Al/Fe2O3(or even Fe3O4 for that matter) thermite will destroy an engine block is wrong. The power of thermite has been blown completely out of proportion by ignorant people in order to scare the common sheeple into bringing agencies like the CPSC into existence.
dagabu Posted October 16, 2009 Posted October 16, 2009 Sorry, can't start a new topic, something horribly wrong with your forums. Questions: How much thermite do I need to melt through an engine block? How big of a whole should ceramic garden pot that contains thermite be? Will a medium burn Chinese fuse (this one http://www.pyrocreations.com/inc/sdetail/79624) ignite Mg wire? I need something to ignite the magnesium with a delay, because I want to be at safe distance and film the thing go off. Another question, what's my mixture ratio should be for maximum effect on the engine block? I'm using ~350 mesh AL, and red F203? Does mixture ratio affect burn rate and burn temperature? Doood, Noobs don't ask questions like that, pace yourself, ask how to make a 1/4" sugar rocket first. Oh, and don't even ask about flash... Oops! D
k9sports Posted October 16, 2009 Posted October 16, 2009 I've seen experiment done on youtube, so I thought I'd try it out on old dodge pickup. So you guys saying it won't burn through an engine block? As for mixture, I'm doing 3:1, but I though there is some recepie for engine block thermite. In any case, I do have the ingredients, 5 lbs red iron oxide, 1 lb aluminum, and mg wire, and the garden pot. So that's 4 lbs of thermite. What can I expect if I put this on top of engine block? I mean, will molten iron and aluminum oxide run down the hood, burn a whole through it? Gas tank is removed completely, tires too, insides are gone as well, so I can do the roof on it. Do you think roof will be more fun than the engine block? What about chinese fuse? Will that fuse that I showed set off magnesium wire? Yea, ney, don't waste money on it? Another thing, so far all the videos I've seen of thermite are fuzzy, you can't see much but a flash. Is there anyway or any filter I could use on camera to capture what's going on there? The biggest thing I'm wondering is if to burn all 4 lbs of it at once, or 1 lbs at a time? What can I see happen to a truck if I burn 1 lb vs 4 lbs?
FrankRizzo Posted October 16, 2009 Posted October 16, 2009 I've seen experiment done on youtube, so I thought I'd try it out on old dodge pickup. So you guys saying it won't burn through an engine block? As for mixture, I'm doing 3:1, but I though there is some recipe for engine block thermite. In any case, I do have the ingredients, 5 lbs red iron oxide, 1 lb aluminum, and mg wire, and the garden pot. So that's 4 lbs of thermite. What can I expect if I put this on top of engine block? I mean, will molten iron and aluminum oxide run down the hood, burn a whole through it? Gas tank is removed completely, tires too, insides are gone as well, so I can do the roof on it. Do you think roof will be more fun than the engine block? What about chinese fuse? Will that fuse that I showed set off magnesium wire? Yea, ney, don't waste money on it? Another thing, so far all the videos I've seen of thermite are fuzzy, you can't see much but a flash. Is there anyway or any filter I could use on camera to capture what's going on there? The biggest thing I'm wondering is if to burn all 4 lbs of it at once, or 1 lbs at a time? What can I see happen to a truck if I burn 1 lb vs 4 lbs? No, it won't bore a hole through the block. The molten iron will burn a hole through the sheet metal of the hood or roof, but you're very unlikely to get much else other than a red-hot puddle of molten iron sitting on the block, or running down the sides onto the ground. If the block is aluminum, you'll may get some melting if you can keep the molten iron in one area, but certainly not a hole down through it. Also, there's a good chance any remaining oil on exposed parts in the engine compartment, the rubber hoses, and plastic parts will start on fire. Regular visco would be extremely unlikely to ignite the mixture. However, some of the colored "flying fish" fuse may do the trick. A sparkler works wonderfully. As for video, if you can set the shutter speed, increase it to the max. A neutral density filter would also help. You want the video to look very dark before the thermite is ignited for best result. Also, read my previous post about creating a hollow cavity down the center of the mixture to the drainage hole in the bottom of the pot. This is critically important for maximum penetration. You need to have a flow of molten iron coming out the bottom as the reaction proceeds, instead of a one big deluge as would happen if you ignited from the top without a cavity.
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