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Author: Subject: Exotic thermites & analogs
t_Pyro
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[*] posted on 13-3-2004 at 08:20


Hmm... This reaction definitely involves a redox change, and redox potentials are the governing factors for such reactions. Enthalpy changes only show whether a reaction is endothermic, exothermic, or thermodynamically feasible under the given conditions. A non-spontaneous reaction can be made spontaneous by changing the reaction conditions.

Or so I've been taught, and that's what my reference book (Concise Inorganic Chemistry, J.D. Lee) says. If there's some other documented text that states the contrary, I'd like to know about it.

About the K<sub>2</sub>O Al thermite that you stated, what are the final products? Pure potassium definitely won't be one of them, unless you manage to perform the reaction in some noble gas, I think... Has anyone actually performed this? If so, what were the reaction conditions?



[Edited on 13-3-2004 by t_Pyro]
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[*] posted on 13-3-2004 at 15:33
Thread


Check the "Sodium" thread. Several members here have prepared sodium in this way. There is at least one set of pictures. Its Na instead of K, but the same argument holds.
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[*] posted on 1-4-2004 at 10:10
Exotic Thermites


I have done some work with NiO/Al and Ni3S2/Al thermites to boost the sintering of nickel-based powders.

The first thing I noticed was that if you ball mill NiO from the pottery shop with aluminium powder for long enough, it "crunches" when you pack it. When in that condition, it gives an even and complete reduction.

I used potassium fluoborate as an initiator, sprinkled over the top of the thermite mixture. I have found that potassium fluoborate will even "revive" a dead-looking mixture. Make sure there's good ventilation.
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[*] posted on 11-4-2004 at 14:11


Hmm, what do you mean with 'initiator'?
I thought potassium fluoroborate Na2BF6 is kryolite (IIRC), which is a flux agent, for the purpose of making separation of Al2O3/metal easier? Isn't it also used for industrial electrolysis of Al2O3, to get aluminium?




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[*] posted on 17-4-2004 at 18:54


Patent #6,679,960 has some interesting info on the uses of thermites in HE mixtures.
I was hesitant on posting this because I am not sure if this is/is not practical pyrotechnics, but I found it real interesting so I decided to post it. If someone thinks this does count as practical pyrotechnics I will delete it.

[Edited on 18-4-2004 by rogue chemist]
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[*] posted on 1-5-2004 at 00:46
exotic thermite


I too have experimented with lead based thermites, I used the lead peroxide from a car battery and powdered iron and ignited it with lithium, as I havent got access to any magnesium :'(

It wasn't very energetic, but did produce a nice hot pool of boiling lead...




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biggrin.gif posted on 30-5-2004 at 21:11


Quote:
Originally posted by chemoleo
This is great stuff!!!
It gives gas volume, cal/g or cm3 etc etc, temperatures for every thermite reaction imaginable, plus many more reactions!!
[Edited on 21-12-2003 by chemoleo]


Chemoleo, do you (or anyone else) still have that file? ... the post seems to have ... gone.

In regards to exploding thermites, wouldnt it be possible to initiate an oxide of a pyrophoric metal to create an FAE type explosion after detonation, the fine metal smoke should readily ignite if not from the detonation, from the atmospheric oxidation. Two bangs for the price of one.

Chemoleo, you mention that you were to try V2O5 thermite, did it ever happen? V should readily oxidise and ignite (300°C ignition of V dust). Perhaps a detonator will be needed to get the thermite moving. Note if it was to work you would end up with a toxic V2O5 cloud ... dont go sucking that in!
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chemoleo
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[*] posted on 31-5-2004 at 16:57
Thermodynamics of thermites AND CaSO4/Al


Yes, it is available on the FTP2. I don't remember whether I put it on FTP1 , I seem to have trouble logging on (in order to check). Probably the IP has changed without me noticing...shame on me, I know...

Anyway, the file on FTP 2 is in
root/chemoleo/Energetic Chemistry/A survey of combustible metals, thermites, and intermetallic.pdf

You have to scroll down for a little to get to the data tables. They are very very interesting :)

On the note of the V2O5/Al thermite - no I didnt get round to trying it yet. I know it is supposed to be one of the hottest thermites that exist (apart from some really obscure ones, like with Hafnium etc). I will try it at some point... but when I get to it, I want to make sure/try I can isolate the metal from it - so somehow I have to avoid it burning away. Seems like a difficult task, judging by the flammability point you mentioned.
Anyway, it's on my things to do list (good thing u reminded me) - the materials are all there, but not yet the time/location/opportunity! Plus I only got about 100 g of V2O5 (it's bloody expensive), and I am always tempted to make bigger amounts... it hurts my soul to start with as little as this ;) !


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.

Well... I guess everything is safe as long as no hard & fast friction is applied!




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[*] posted on 31-5-2004 at 23:28


My computer "skillz" are letting me down with this ftp thing, gonna have to swallow my pride, be an annoyance and ask for a second time how to get into it... :(

To make sure I wasnt just making up stories, I found an msds mentioning the 300° ignition - http://www.camd.lsu.edu/msds/v/vanadium.htm Maybe theres a difference between "can be" and "will be". I guess you could look at the smoke to see whats happening, if its oxidising during burning it should turn dirty yellow brown.

V2O5 runs around $120AUS (~$90US) a Kg here .... cheap enough to burn :D

"Extremely toxic. May be fatal if swallowed, inhaled or absorbed through skin. Note low LD50s below. May cause reproductive defects. May cause severe irritation or burns on contact. Typical TLV/TWA 0.05 mg/m3." Yay for V2O5!

Interesting that the plaster thermite would ignite by drilling ... must try shooting it.


[Edited on 1-6-2004 by Axt]
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[*] posted on 5-6-2004 at 23:39


I had my first experience with thermite today. I used home prepared CuO and 400 mesh spherical aluminum.
The copper oxide was prepared by adding solid sodium hydroxide to a almost boiling copper(II) sulfate solution. The precipitate was then filtered, air dried and finally over an alcohol burner flame for 10min.
2.2g of the CuO was mixed with .5g of 400 mesh aluminum and set off with a short lenght of Mg ribbon. There was a nice "fwump" and it all was gone instantly.
I was unable to find remanents of the mix in the surrounding area except for a few lumps of aluminum oxide. Surprisingly enough, the vessel it was in when ignited(base of a cone shaped drinking cup) was left unharmed:o except for a fine coating of copper.
All in all this was very cool and is definatly something I will try again.
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[*] posted on 21-7-2004 at 22:41
Lithium thermite


Has anyone ever contemplated this before? Or is it just so dangerous that its absolutely not possible, even with 1 gram amounts?

And if it is possible, how would you go about making the thermite? Just toss oxide on the lithium metal? Would it ignite itself?




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[*] posted on 21-7-2004 at 22:57


You would have to powder the Li in order to make it work for thermite. But, on contact with air the powdered Li would oxidize.
I can see a Li based thermite working if made, stored, and used in an inert gas atmosphere. But other than that I cannot see it working due to the Li reacting with the air.

Are you looking for a use for all that Li you have recently extracted from batteries?;)
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[*] posted on 22-7-2004 at 01:34


Yes :D

Would the nitride layer protect the Li from further oxidation? I was hoping that shredding it to bits would be enough :(

Got any better ideas to use the lithium? :)

[Edited on 22-7-2004 by Saerynide]




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[*] posted on 22-7-2004 at 09:23


I dont see why it would have to be powderd, i dont think Li has an extreme melting point, just heat it till its a liquid, that would start the reaction too i think.



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mad.gif posted on 22-7-2004 at 20:37


Gah!!! I cant even get iron oxide thermite to ignite (I tried today for about 2 hours with 3 different kinds of fuses/igniters!!! :mad: ), let alone get the experience and patience to try lithium :(

By the way, please someone tell me that 1 gram (I tried that today) amounts are extremely difficult to ignite, and that large amounts (like 50-70g) amounts will be much easier.... I really want this demonstration to work (its for a friend's present) :(




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[*] posted on 22-7-2004 at 21:23


A few questions Saerynide;
1) How was the iron oxide made?
2) What was the reducing agent used, Al?, and if so, what mesh/size
3) How were you attempting ignition?
4) Did you use a stoichiometric mix of reactants?

All these are necessary to find the problem with your thermite.

[Edited on 23-7-2004 by rogue chemist]
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[*] posted on 22-7-2004 at 22:47


I got the oxide from spent oxygen absorbers and handwarmer packs. Its black and makes those spikes when you put a magnet to it, so I figured it would be Fe3O4. Oh yeah, I also used a neodymium magnet to get only the oxide while leaving everything else behind.

I used Al powder flakes from an art shop. I dont know what mesh it is, but its pretty fine. It smells like its coated with some kind of oil to keep it metallic, but I figured it might still work. I tested it with my drain cleaner, and it is indeed Al. I tried washing it with acetone to remove whatever was on it, but it reacted worse with the draincleaner than before :o I was intending to do 2 runs, one with the Al, and one with Mg shavings/powder, but the first run got me too pissed to do the other :mad: But I guess if the Al doesnt work, I'll try the Mg next time.

I tried a sparkler (it wouldnt even light cause I peeled the wrapper from it... damn thing... needs a freaking wrapper to light :mad: ), Mg shavings/powder with sparks from a flintstone and a few times with matches, and lastly I tried KMnO4 + glycerin. The KMnO4 reaction makes a crust of green stuff (what *is* that? Ive never seen it before in the previous times I tried that reaction) and MnO2 over the thermite. I guess a 1 gram pile just doesnt work with permanganate :mad:

I suppose if I didnt mess up that sparkler, it mightve actually ignited... but who knows?

I dont have a scale that can measure well in less than 5 gram increments (yes, très crappy, I know :P), so I did 50/50 volume cause I didnt want to do 20 grams on my first try.




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[*] posted on 22-7-2004 at 23:15


I cannot say much about Al with a coating as I have no experiance in that area but I think I would try a stoichiometric mix. The 50/50 by volume I think has too much fuel. When I made my CuO/Al thermite, the ratio by volume(if I remember correctly) was about 4:1. Stoichiometrically for every 5g of Fe3O4, 1.55g of Al is used. Why not make a slightly larger batch? If it does not work again, put the mix in water, stick a magnet in and you got your Fe3O4 back, then filter any you got your Al back.:cool:

Also with your method of ignition, try tieing a few short (1-2";) pieces of sparkler to your main fuse sparkler where it goes into the thermite. This additional heat may make the difference between success and failure.

Ps: I think I will try this mix out in the next few days if I have a chance.
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[*] posted on 22-7-2004 at 23:38


I was planning on doing a stoichiometric amount but with Mg instead of Al for my friend using about 70g (we're gonna do it at the beach), but I really can't do a larger batch at my place. My neighbors will probably call the cops and my parents will nuke if anything happens to the driveway :(

I dont think I'll get the chance to test again (cause I have to wait til parents are out) before doing the large Mg batch :(

One more thing, since I never got to test the Mg mix, what does it look like when it reacts? I would assume it burns hotter and much brighter with tons of white light? And how much more dangerous is it (eg: tons of molten metal spitting everywhere, etc)?

[Edit]: Can I colour thermite with ground up coloured sparklers? I added some ground up green sparkler to my 1gram mix, but you know the rest...

[Edited on 23-7-2004 by Saerynide]




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[*] posted on 23-7-2004 at 04:44


Saerynide, you mentioned about that the KMnO4 + glycerin failed. If you had made a small mound of KMnO4, put the thermite mixture at the summit:D, drip in the glycerin in, and see whether this works. Should it work, I'm goin to try this next.

I am wondering, if you mixed the potassium permanganate powder in with the aluminium powder, add glycerin, would the resulting thermite reaction, reduce the MnO2 produced to manganese metal?




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[*] posted on 23-7-2004 at 05:39


DO NOT MIX KMNO4 WITH AL!! It is very unstable and dangerous!



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[*] posted on 23-7-2004 at 05:43


I thought I'd test a few thermite mixes as the weather was nice today. :)

All the pics are 2048 x 1536

First was Fe2O3/Zn. It worked but burned very slowly.

Before http://koti.mbnet.fi/otto2000/thermites/Fe2O3_Zn_before.JPG
After http://koti.mbnet.fi/otto2000/thermites/Fe2O3_Zn_after.JPG

Next was MnO2/Zn. This was the best of the three I tested. It burned quite fast and made some smoke too.

Before http://koti.mbnet.fi/otto2000/thermites/MnO2_Zn_before.JPG
After http://koti.mbnet.fi/otto2000/thermites/MnO2_Zn_after.JPG
Movie http://koti.mbnet.fi/otto2000/thermites/MnO2_Zn.MOV

Last was CuO/Zn. This mix burned with decent speed but didn't make much smoke.

Before http://koti.mbnet.fi/otto2000/thermites/CuO_Zn_before.JPG
After http://koti.mbnet.fi/otto2000/thermites/CuO_Zn_after.JPG
Movie http://koti.mbnet.fi/otto2000/thermites/CuO_Zn.MOV

The movies are slightly fucked up 'cos I had some trouble lighting the mixtures :( And sorry about the .mov files, I had to film them with my digital camera.

All the chems were +400 mesh but probably slightly humid as it has been raining here all the time. :(
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[*] posted on 23-7-2004 at 06:03


The burning paper set off the MnO2 mix? :o



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[*] posted on 23-7-2004 at 14:06


Oh, that's not that unusual.
CuO + Al 300 mesh is also ignitable by burning paper.
I really would work with larger amounts, too, as they are more easily pressed/confined/mixed. Plus make sure that the proportions are close to stoichiometric. Then a sparkler should suffice.
Also I wouldnt trust the purity of the Fe3O4. There may be a number of compounds that may impair the reaction. A pottery supply is the best place to get oxides, remember?
To this point I have not discovered a single thermite that was not ignitable by sparklers, even with Al cuttings (1-2mm thick, sometimes cm long) it worked ok if several tied together sparklers were used (with Fe2o3).

So come on, saerynide, no excuses!

PS nice work IPN. Why Zn instead of Al? Obviously the reaction will be much less energetic...

PS2 With respect to Li thermites - I guess they will be less sensitive to ignition, but produce not as much energy as the Al oxides - due to the respective heat of oxidation.
Regarding Al or Mg - Al is definitely less dangerous in most cases, I remember just the differences betw. Al or Mg + NaOH - the former glows, the latter explodes! Despite similar oxidation energies! From other less pleasant experiences I remember Mg being quite a bit more dangerous.
Also, the colour difference should not be noticable, in most htermites, due to both having very high reaction temps.

[Edited on 23-7-2004 by chemoleo]




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[*] posted on 23-7-2004 at 18:18


Saerynide your problem could well be with the oil coated Al, I've tried this and it wont ignite and sustain unless a lot is used as well as a hot Mg igniter. Atomised Al (resin filler) is no problem.

<center><img src="http://www.sciencemadness.org/scipics/axt/copperburst.jpg">
<a href="http://geocities.com/roguemovies7/">MOVIE AVAILABLE</a></center>

Above is frames of a detonator initiated 100ml CuO/Al charge, It was placed on a 2mm steel plate, somewhat expected, but it didn't dent it at all, a urea nitrate charge was used for comparison (these were larger charges then the others tested on that plate, so no comparisons between them).

Along with this movie there is also targets made from the same initiated with a .25-06 (never tried anything less). First charge is a matchbox full of CuO/Al, second a 350ml container full but the movie is crap, turning up the brightness (was at dawn) made it all red but it did look really good.

[Edited on 9-12-2005 by Axt]
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