Thermite mixture

[FrKoNaLeaSh1010]

mumbles thanks for the idea of the thermate. Do you know of any places i should start looking for thermate formulas? I dont have all my old ebooks from the info pool all i have is a link to wouter vissers comp database and passfire but i dont think they have thermite/thermate comps in there. You dont have to give me the formula if you dont want to just point me in the right direction. I am going to search on passfire and in the comp database i have now and if i find it i will post it for anyone else interested. And thanks for the tip about converting to the hydroxide...i had a feeling there was a step in between before the thermal decomposition. I remembered because i made some CuO for blue stars a while back before ordered a pound of it...buying it is deffinitely easier than making it. and yeah i dont wanna mess with NOx....already had enough experiences with it....got a good lung full of it once and was in pain with every breath for like 3 days. thats what you get for not wearing a lab grade respirator. It made me stop doing nitrations for a very long time after that incident but of course one cant stay away from pyro forever....i have been out of it for years untill the past week or so

 

Also i just wanted to comment that a couple of the photo flashes i tried back in the day are deffinitely very potent flash powders and very bright.

[Mumbles]

I might have been wrong about it being fuse sensitive. I found this on the Wikipedia article for Thermate. I doubt the binder is important or vital in any way to the formula. Just a way to cast it I suppose. I've heard reports of being able to use a slow flash type of composition to be able to light the thermite. 60 Parts KNO3, 20 parts Al, 10 parts Sulfur or something to that effect. It's cast into a pellet and lit, and is supposedly said to light thermites.

 

68.7% thermite

29.0% barium nitrate

2.0% sulfur

0.3% binder (such as PBAN)

[FrKoNaLeaSh1010]

thanks for the formula mumbles. I am not really worried about flame sensitivity as there are tons of ways to ignite it....like you said a slow flash would work or any slow yet hot burning mixture. Does anyone have any info on the thermates? If it is just normal thermite with barium nitrate and a small percent of sulfur i dont really see the advantage. Obviously the barium nitrate is there as a oxidizer and when you think about it barium nitrate/aluminum/sulfur is a flash powder. So what is it just an easier igniteable and hotter burning thermite? Since there is a percentage of flash powder in it that would make it easier to ignite or perhaps the barium nitrate adds oxygen to make it burn for fiercely.

[Richtee]

I might have been wrong about it being fuse sensitive.

 

My ears say it IS possible. Like I said..I DID coil the visco up into a few folds... and it was in the mix for about a second. But trust me...sounded like a solid BP salute. Low tone, and crushed the can I was hoping to turn to slag.

[psyco_1322]

I just happen to have some rail road thermite, its CuO/Al, made with coarse CuO "flakes" and is a stubborn sucker to get to light. I even have the little pot that its used with. My dad had it for years and we never could figure out what it was until he gave it to me a while back and I took a real good look at it and it click as to what it was. I couldnt get straight Mg ribbon to light it, so I had to turn the the pile of comp red with a torch to up the reaction temps and the touch off some ribbon in it. It went up like flash and threw a bunch of molten copper every where. I believe the use it to attach some kind of grounding straps from one piece of track to another. Ive seen the containers around where its been used before.

[FrKoNaLeaSh1010]

The only reason why it was hard to ignite was cause of the coarse flakes. Finely powdered CuO with aluminum or magnesium goes up with fuse like a flash powder. I have heard of iron oxide thermite used in welding but I like the idea of using the copper oxide because then the weld would be conductive due to the copper.

[FrankRizzo]

I just happen to have some rail road thermite, its CuO/Al, made with coarse CuO "flakes" and is a stubborn sucker to get to light. I even have the little pot that its used with. My dad had it for years and we never could figure out what it was until he gave it to me a while back and I took a real good look at it and it click as to what it was. I couldnt get straight Mg ribbon to light it, so I had to turn the the pile of comp red with a torch to up the reaction temps and the touch off some ribbon in it. It went up like flash and threw a bunch of molten copper every where. I believe the use it to attach some kind of grounding straps from one piece of track to another. Ive seen the containers around where its been used before.

 

It's likely CadWeld or something similar. You're right, it's used to bond the sensing straps to the track, which requires a massive amount of heat to be released in a period of time shorter than the mass of the track section can sink it away.

[psyco_1322]

Yep its CadWeld 45. The reducer in it is also kinda coarse, its also really shinny. It may not be Al, might be a magnalium alloy. Though I would think it would light a lot easier if it was. Ya that CuO/Al with dark pyro is neat stuff. Gives off the brown smoke cloud and makes a nice whop noise in even small quantities.

[Richtee]

You actually made flash. It's a sort of photo flash I've used a couple of times

Impressive. Made a salute 3" with 40 grams. Attached a hot burning star to the time fuse. I'm anxiously awaiting this shell. I did a test earlier, and the compound - UNCONFINED- gives an IMPRESSIVE deep throated BOOM! Almost akin to a nice black powder salute. A real chest thumper without massive quantities.

[Richtee]

Impressive. Made a salute 3" with 40 grams. Attached a hot burning star to the time fuse. I'm anxiously awaiting this shell. I did a test earlier, and the compound - UNCONFINED- gives an IMPRESSIVE deep throated BOOM! Almost akin to a nice black powder salute. A real chest thumper without massive quantities.

Failed. Dunno why for sure, but on autopsy, the star broke loose from the time fuse. I assume that's it. This mix is rather insensitive apparently.

[Miech]

You might want to try an 70/30 flash booster if you want to be sure about ignition. About 3 grams should be sufficient for a 3" salute. Barium sulfate needs a rather large amount of energy to release its oxygen.

[Scott2547]

Please share your thoughts with me.

Where did I go wrong?

I tried 3 time to make the thermite comp, in the following amounts.

48 grams of fe3o4/ 16 grams of 300 mesh powdered Al/ magnesium ribbon

60 grams of fe304/ 20 grams of Al as mentioned above.

20 grams fe304/ 20 grams AL.

The magnesium burns brightly but the mixture of Al & fe3o4 remains , no sparks no burning ???

Thank you for your input.

[Scott2547]

3:1 iron oxide to aluminum, so the first two should have worked, as well as the third, I would think.

 

So there could be something wrong with the chemicals (aren't what you think they are), it's not mixed well enough, it's not fine enough or it's too damp.

 

If you have the chemicals available, mix up this comp (from Firefox) and use to ignite your "thermite":

Thermite Prime % by weight

Potassium Perchlorate 65

Aluminum, fine (any form) 15

Red Iron Oxide 15

Magnesium, fine (any form) 10

Moisten with Nitrocellulose Lacquer solution 50/50 (NC lacquer, Acetone) and press into a "cookie", allow to dry and break into 1/2" pieces for use.

 

If this doesn't light it, somethings definitely not right.

 

Thank you for the advice. It will take a few days to aquire the materials but I will try the comp you listed.

Do I need fe2o3 red or will the fe3o4 black I have surfice for the compound?

I have watched several videos staring fe3o4 and AL, and was impressed at the power of the mixture.

I will dry the present materials in my welding rod oven , to eliminate any moisture.

Thank You.

[tentacles]

Mg ribbon is fairly unreliable for lighting thermites, I've had good success with BP + Mg, or any hot star mix. Anything with barium nitrate should do, or a white metal fueled star of any type. Bp+ Ti would likely work. Just make a NC slurry of it and slather some on top.

[Mumbles]

Be careful with what you call black iron oxide. Traditionally, black iron oxide refers to Fe(II) Oxide, which is FeO. Fe3O4 is a spinel complex and is traditionally Fe (II,III) Oxide. There are 2 iron (III) iron ions, and one iron (II) irons in the complex. The mix gives rise to it's magnetic nature. Fe3O4 is more traditionally called magnetite.

 

FeO : 4:1

Fe2O3 : 3.3:1

Fe3O4 : 3.2:1

 

Those are the roughly stoichiometric ratios. I've heard of people using pellets of 6:3:1 KNO3:Al:Sulfur being used to ignite thermites. A lot of things will probably work. You just want to make sure there is a lot of metals in there to get the temp up.

[Scott2547]

Mg ribbon is fairly unreliable for lighting thermites, I've had good success with BP + Mg, or any hot star mix. Anything with barium nitrate should do, or a white metal fueled star of any type. Bp+ Ti would likely work. Just make a NC slurry of it and slather some on top.

 

Could/should Pyrodex + MG be used as a subsitute for the BP + MG you wrote of ? If so what recomendations do you have for the mixture of the 2 items in weight.

Thank you

 

My first success ...

 

I added .5 gram of Mg shavings to a 30/10 mixture of the fe3o4/Al, great show. It took a propane torch to ignite mixture though.

I had to try another mixture.

 

To the previous mixture I added: 1 gram Mg shavings a 2 gram coil of Mg with 1.5 grams of smokless powder on top using 3" of knoted 2mm WP Visco. This mixture took less than a second to transform a soda can into little more than a memory.

 

Many Thanks to all who have shared there knowledge with me..

 

If you would like to share more knowledge; I want to learn the proper way to make Rocket Candy.

I beleive that have all of the needed ingredients on hand. I would like to make about 1oz dry weight.

Edited October 19, 2008 by Scott2547

[optimus]

Mg ribbon is fairly unreliable for lighting thermites, I've had good success with BP + Mg, or any hot star mix. Anything with barium nitrate should do, or a white metal fueled star of any type. Bp+ Ti would likely work. Just make a NC slurry of it and slather some on top.

 

Falling leaf fuse also does a great job at igniting thermites.

[Trog]

I have always been led to believe that for CuO/Al the ratio is 4.42:1

 

I can confirm that 50g of this in a bog roll core lit by some visco makes a lovely bang and fireball. No spatter either.

[Arthur]

Iron oxide and aluminium makes an engineering thermite for rail welding and other uses. If you use copper oxide it's likely to go high order and spread fire and molten metal all round.

[cmjlab]

If you test again, you can try this ratio....

 

According to Richard Nakka's website the stoichiometric formula is as follows:

 

3 CuO + 2 Al -> Al2O3 + 3 Cu

Dh = -4.12 kJ/gram.

The stoichiometric mass ratio of oxide to metal is 4.56:1.

 

With that being said, his notes say there was leftover material not consumed by the reaction. So as is often pointed out, stoichiometric formulas don't always burn the best for pyrotechnic purposes.

 

Edit: they are both very similar, but I did use this ratio for matches with some success. There's videos on here somewhere.

 

Edit 2: **of course as you alluded to, the mixture is very reactive and should NOT be made in large quantities. The reaction is similar to flash powder, and is reportedly friction/impact/static sensitive.**

Edited December 18, 2022 by cmjlab

[Trog]

Iron oxide and aluminium makes an engineering thermite for rail welding and other uses. If you use copper oxide it's likely to go high order and spread fire and molten metal all round.

Yes which is why you use cupric oxide if you just want to make a report.

[tti82phys]

With that being said, his notes say there was leftover material not consumed by the reaction. So as is often pointed out, stoichiometric formulas don't always burn the best for pyrotechnic purposes.

I suppose if there's a slight excess of fuel compared to oxidizer, some of the fuel is oxidized by surrounding air and the mixture releases a bit more energy per gram because of utilizing ambient oxygen. But then it will also be slower burning than the stoichiometric mix.

[cmjlab]

Im not sure that stoichiometric = quickest burn speed, as much as it means complete consumption / balanced formula. I feel like there are a lot of other factors at play like particle size, how well blended, available atmospheric oxygen.or self sustaining, etc.

 

I know that sometimes a stoichiometric formula's burn speed is much slower than an oxidizer rich formula's, which may not consume all the fuel but would likely increase the rate burn speed until the oxidizer is consumed.

 

I'd be curious to hear Mumbles take on it if he gets a chance, as he seems pretty knowledgeable on the chemistry aspect of pyrotechnic formulas (which I am not).

 

I believe flash powder and black powder are both good examples of this.

Edited December 22, 2022 by cmjlab

[cmjlab]

Maybe i misunderstood your post too, if so I apologize.

[tti82phys]

If you make a solid block of chlorate-sugar mixture with some binder, break it to little shards and mix some of those evenly with a thermite mixture, it will most likely increase the burn rate a lot because the KClO3 mixture has a much lower ignition temperature. But better ignite it in a way that allows staying at a good distance, as you can't know if it throws molten metal droplets all around.

 

In some old post in this thread, someone mentioned using calcium sulfate or calcium carbonate as an oxidizer in a "thermite mixture". I can't remember having seen that before, but the reason why someone would call that a thermite mixture is probably that it's as difficult to ignite as Al-Fe2O3. Clearly in those reactions the sulfate or carbonate ion acts as the oxidizer, not the calcium ion.

 

A reaction going "high order" in this case means that the burn rate accelerates instead of the fuel being consumed at constant rate, I guess.