Sciencemadness Discussion Board

Exotic thermites & analogs

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Polverone - 12-8-2002 at 12:46

Many oxides/salts of less reactive metals can react vigorously when mixed with an appropriate quantity of magnesium or aluminum and initiated by high temperatures (or, in some cases, by a detonator). The most common of these mixtures, of course, is aluminum and iron oxide.

I've experimented with a few other different mixtures. Anhydrous CuCl2 and aluminum is easy to ignite, though not terribly vigorous. I was able to wrap some CuCl2 powder in aluminum foil to make a tube and ignite the tube at one end with an alcohol burner. Combustion progressed with a small amount of pinkish flame (I would have expected green or blue, but it was pink) and considerable smoke, with solid copper being deposited. CuCl2 and 300 mesh aluminum powder burned quickly.

Flour-fine CuO from a ceramics supplier burned with extreme vigor with 300 mesh aluminum in a stoichiometric ratio. I ignited one charge of about 30 grams at night with a hot aluminum/sulfur ignition mixture. The thermite mixture was in an aluminum can with the top cut off and the igniter laid on top. The CuO/Al burned in a fraction of a second with a hearty "whump!" and shot glowing debris (likely the igniter slag) 10 meters in the air.

A 50 gram charge of the same mixture was initiated in the daytime with 2 grams of HMTD. There was a satisfying flash and explosion, and a large cloud of brownish smoke (vaporized copper mixed with aluminum oxide) rose above the test site. It is interesting that this mixture yields *no* permanent gases at STP yet exploded with sufficient force to make the plastic stand holding the charge vanish without a trace.

I have oxides of tin and chromium on hand, which I hope to try at some point in the future. I would also like to try lead salts/oxides, though I fear excessive sensitivity with these, and also with silver salts/oxides, though I fear sensitivity *and* price with them.

Have any other experimenters here wandered off the beaten path of "standard" thermite?

Rhadon - 13-8-2002 at 08:40

I just experimented with PbO / Al. I put it into a container that was made out of a piece of aluminum foil and tried to ignite it with an alcohol burner, without success. Though, the aluminum case began to glow and started to melt down, what indicates that some energy was given off (usually I'm unable reach the mp of aluminum). I tried it once again, with the same result.

So I gave it another try, but this time I put some sulfur on top of the mixture to lower the ignition temperature. It didn't burn as bright and not as fast as I expected (both components were very fine), but it worked quite well.

vulture - 13-8-2002 at 11:06

That's strange, I've always read that PbO/Al is very sensitive and can explode without confinement.

Polverone - 13-8-2002 at 11:31

I have read the same thing about lead oxide and Al, but I believe the references I had were speaking of minium, red lead, Pb3O4. Also, as I'm sure anyone who has ever experimented with pyrotechnics knows, particle size makes a tremendous difference. Rhadon, how fine were the particles of your components? I hope that your experiments are small and cautious. The CuO/Al mixture I used was extremely vigorous, and I would expect that lead-based mixtures could be even more so.

If you are having difficulty achieving ignition, try placing a 1:1.78 (or just 1:2) mixture of Al powder and sulfur powder on top of your main charge. This mixture is easy to ignite with a fuse and relatively tame but burns hot enough to melt steel and ignite thermite mixtures of all sorts.

Rhadon - 13-8-2002 at 12:43

Perhaps the ignition was a bit hard because PbO exists in two forms - a red alpha- and a yellow beta-form. I don't know what the difference is, though.

I used lead hydroxide and heated it until it had a yellow color. This should have yielded the beta-modification. I made it as fine as I could, the particle size should be approximately like that of flour.

The aluminum I used is very fine. I don't know what mesh it is, but it can be used for painting purposes.

Quote:
I hope that your experiments are small and cautious.

Yes, of course :) I only used amounts as small as about 1 g and had 'security precautions'.

I might try the Al/S mixture for ignition in the next days when I'm in the right mood. There is still some PbO that wants to be used :)
Does anyone know how sensitive Al/S is?

Al/S sensitivity

Polverone - 13-8-2002 at 14:45

Do you mean sensitivity to heat, friction, impact? I have only tried initiating it with flame. It is considerably harder to ignite than black powder, but it is still easily accomplished with the flame from a fuse or match. It burns slowly with much heat. Try it, you'll like it ;-)

Rhadon - 13-8-2002 at 15:12

I see, I should have mentioned what kind of sensitivity I was thinking of. Actually, I wanted to know about all three, but primarily sensitivity to heat and friction. Heat sensitivity because of the ignition temperature and friction sensitivity because it's always good to know how careful you have to be when mixing the components.

Rhadon - 22-8-2002 at 18:58

In the last days I experimented with Al/s. Before applying it to PbO/Al I wanted to try igniting the ordinary Fe3O4/Al thermite with it. I did so three times without having success. Since this was probably due to the very small scale, I wanted to give it another try with about 15 g of Fe3O4/Al. Unfortunately, I didn't have enough Fe3O4, so I searched for another metal oxide in my lab. I selected MnO2.
About 14 g of MnO2/Al could be ignited easily with Al/S, and the reaction worked unexpectedly well, even though it was not as vigorous as Fe3O4/Al, of course.

Madog - 26-8-2002 at 20:25

i have used PbO/Al once. it was easy to ignite but not as good as i expected. Al/S sounds interesting.

Kwel

KABOOOM - 29-8-2002 at 16:47


here (Iran) teenagers make a kind of very dangerous torpedo using red lead and a kind of very fine bright aluminum powder (the word we use in persian does not mean Al powder and its main use is for painting and things like that to add brilliant effect)
anyway, here is how they make the kwel torpedo
1. mix the Pb3O4 & Al powder very carefully
2. sprinkle half of the powder on a sheet of plactic bag then cup the sheet then put some stone in it and pour the rest of the powder now wrap the above part of the cup-form till you have a ball with a plastic-bag wall (that contains Pb3O4-Al mix and pieces of stone in the middle)
3. (the most foolish part!) wrap the ball with electric-tape very TIGHT!!!!!
this torpedo is Terribly sensitive to impact there is no need to throw it very hard
it's Incrediblly powerful. many kids have been injured and even died with the torpedo

Red lead & aluminum

Polverone - 30-8-2002 at 10:24

Have been used to create crackling microstars ("dragon's eggs") in the past, but the toxic lead is now replaced by bismuth trioxide (at least in US fireworks). I was aware that the mixture was explosive but didn't realize it was so sensitive. Impact-explosives can be fun but are generally a bad idea from a safety standpoint.

PHILOU Zrealone - 9-9-2002 at 14:43

There was an extremely good post about thermites on alt.engr.explosive NG that was posted by Don Haarman 2 or 3 month ago!
You have a very long tale very instructive that explains all you want to know about all kinds of themites with various oxydes!
See:
Subject:
Re: extinguishing thermite
Date: Sat, 03 Aug 2002 02:05:43 GMT
From: "donald haarmann"
Organization:AT&T Worldnet
Newsgroups: alt.engr.explosives, sci.chem, rec.pyrotechnics
References:1 , 2 , 3 , 4 , 5 , 6

Then you would have 18 pages of pleasure! I don't put those here since they are there! and I'm not sure this reply case has enough memory to hold 18 pages!

PH Z:cool:

Oh, indeed

Polverone - 9-9-2002 at 15:30

I have seen this message. It contains much excellent material. He also cited "Civilian and Military Pyrotechnics" within that message, I believe, which is what inspired me to scan it.

PHILOU Zrealone - 13-9-2002 at 07:38

To be honnest...think a bit to what will happen if you blast a thermite mix?
It will spray all arround and take the reactants away from each other fast before they have had the time to react!
Even a fast exploding thermite won't exceed 500m/s while any low detonation is over 1,5km/s so better use only the Al/Zn/Mg powder in the explosive immediately because the other metal oxyde will be only dead weight-inert body!

PH Z
:):D;):cool::o:P

Polverone - 13-9-2002 at 11:27

I found a reference on Usenet (yes, I know, not exactly a peer-reviewed source) to exploding CuO/Al thermite mixes which inspired me to try it myself. It may be because of the relatively small charge in a confined area, but I am fairly certain that almost all of the CuO/Al mix reacted without dissipating (when I initiated a pill bottle of the mixture with HMTD). When I've had mixtures containing Al fail to completely react/detonate, it is very easy to see the powder on nearby surfaces. There was no residue left behind in this case, not the smallest fragment of plastic or the merest hint of aluminum. Bear in mind that I was using very fine and well-mixed powders, whereas traditionally thermite is made with coarser materials.

SiO<sub>2</sub>/Al

Rhadon - 19-9-2002 at 10:57

I heard that a thermite mixture consisting of SiO2/Al is used to make elemental Si (but not commercially). Has anyone ever tried this?

Where did you hear this?

Polverone - 19-9-2002 at 16:47

I've heard the same thing just recently. I can't remember if it was from a large inorganic chem book I've been reading, or Usenet messages, or Military and Civilian Pyrotechnics, or something else.

In any case, the Unknown Reference stated that magnesium could be used to reduce SiO2 to silicon, but that some magnesium silicide would also be formed. It further stated that if an excess of aluminum powder were used instead, no silicide would form and the impurities could be removed by dissolving them in NaOH solution.

This sounds well worth trying... not that I have any use for raw silicon.

You guessed it

Rhadon - 19-9-2002 at 17:37

The source is an inorganic chemistry book. I don't have it at hand for reference since it is from the library, but if I remember correctly the procedure recommends to clean the final product by boiling it for some time in HF and washing it with water afterwards. This will also remove SiO2 impurities.

SiO2 / Al experiment failed

Rhadon - 23-9-2002 at 09:38

I tried the SiO2 / Al thermite mixture recently, the SiO2 coming from unpurified window glass (composition should be about 72% SiO2, 14% Na2O, 9% CaO, 4% MgO and minor amounts of other additives). Yes, it was highly polluted, but I thought that 1/4 of impurities wouldn't stop the reaction if it has finally started. Since I expected that it would be hard to ignite, I did it in several steps as shown in the figure below.



Up to the point where the SiO2 / Al should be ignited, it worked all well. But the latter was left back unreacted, having a thin crust of scoria on its top. Probably the temperature which is generated in the reaction between MnO2 and Al wasn't high enough, or it was due to the impurities.

a_bab - 4-10-2002 at 09:26

Great pics Xoo ! The Lead oxide/Al is similar : very bright and fast.

Rhadon, for your reaction you must use sand (nearly pure SiO2), not glass powder. Also the crusty residue (Al2O3 + Si) must be reacted with HCl. If Mg powder is used instead of Al, you'll get also silane (SiH4) generated by the reaction with HCl. This is a pyrophoric gas (and very toxic as well). The remainings might be pretty pure Si.

Polverone - 4-10-2002 at 10:55

Good pics. I'm kind of surprised that you were able to get 3 pictures. When I tried this mixture, it burned extremely fast - almost like flash powder. Now of course you should try the next step: explosive initiation!

BTW, did you just use an ordinary fuse to light this mixture or did you use some sort of priming mix too? I think it is sensitive enough that you might get it going with just a big hot fuse, but I always used an Al/S prime mixture (when I wasn't using a detonator).

Polverone - 4-10-2002 at 12:21

That flash circuit does sound like a viable method for initiation. If I were you I would try it.

When I explosively initiated my CuO/Al thermite, I placed the mixture (about 30 grams) into a narrow pill bottle. I placed a straw filled with HMTD down the center of the mixture as my detonator. I didn't cap or reinforce the pill bottle in any way.

a_bab - 4-10-2002 at 23:52

Since the Cu/Al mixture is capable of a very fast burning (same as Pb3O4/Al), and I have vaste experience concerning the last one, I can say that if initiated with a detonator even open (a pile on a sheet of paper with the det. in the middle) the mix will explode (I don't say detonate), so it'll explode with a loud report and a deep soud (=low speed). And if is confined enough (a motor rocket) it'll eplode for sure every time. It's very reasembling with the whistle powder from this poit of view (used to make nozle-less rockets)

I wonder if .......

Boob Raider - 20-10-2002 at 18:58

the PbO2 from car batteries would make a good incendary with Al powder. And NiO2 with Al powder. Also if one were to make fine granules with the thermite mix and pack it loosely around the ignition charge ..... it should generate a large heat explosion. Finer granules would make an intense heat explosion and coarser granules would work great as incendaries.
I had set off a charge once of Aluminized BP surrounded by Hexamine soaked in naptha ...... and DAMN :D did it put out a heat wave. (I miss those days when I could buy kilos of hexamine as camp fuel)

madscientist - 20-10-2002 at 19:37

I would think that PbO2/Al mixes would be violently explosive and dangerously unpredictable.

Alkalai Aluminum Hydrides

PrimoPyro - 27-10-2002 at 13:46

Well, what about Fe3O4 and KAlH4? (shiver in fear at the thought of its sensitivity)

That should be quite 'hot'.

Lithium aluminum hydride is common, and potassium aluminum hydride would provide more energythan the lithium salt.

Question is, would they burst into flame upon contact, or would a mixture be stable enough to be set off intentionally. Regardless, even if it is 'stable enough' I'd never recommend storing the mixture, as it would provide MUUUUUCH more energy than standard thermite, I think.

PrimoPyro

Nick F - 27-10-2002 at 14:21

Just wondering, did anyone ever try mixing CuO/Al with a small amount of binder, such as polyester resin, before either detonation or ignition? I'm particularly interested in detonating bound mixtures...
Anyone know if it works? It could make good little flash-bangs...

vulture - 28-10-2002 at 09:33

How about CaC2/Fe2O3? The formation of CaO should gives quite a good enthalpy.
Not to speak of KMnO4/CaC2.....

bonemachine - 29-10-2002 at 04:04

Is it posible to use CuO with fuels of lower ingnition point?

vulture - 29-10-2002 at 14:54

How about Ag2O2 and Al/Mg/CaC2/ LiAlH4? :D

bonemachine - 31-10-2002 at 07:55

I am thinking to make 200grams of CuO/AL. If i confine this in paper tube will it be powerfull like flash? Or not?

bonemachine - 31-10-2002 at 11:53

So it seems that it has alot of blasting power. But compared to common flash powders how powerfull could be 200grams??

Also I realy don't understand how CuO/Al detonates. If it would realy detonate then simply CuO could also do. Am i right? Or the mixture can ingnite so fast before the elements separate from each other from the blast?

bonemachine - 1-11-2002 at 11:36

Maybe this doesn't got to do much with thermite but i was always wondering what could hapend if a hot glowing thermite falls inside a container full of potasium nitrate. My first thought was that a very violend deflagration will occur trowing hot particles everywhere. But on second thought if you consider that the heat is so high to decompose even water then why not to detonate potassium nitrate? I am planing to test this soon.... Any one has any experience about this or just imagine what could hapend if thermite ingnites in a container with a nitrate oxidiser?

bonemachine - 2-11-2002 at 09:56

I made some CuO (by heating strongly Cu(OH) from electrolysis cell until it turns totaly black) and mixed it with 600mesh Al flake. I have trouble ingniting it. I used a barium nitrate/Fe fuse and the AL sparked a little bit but failed to deflagrate with CuO. What temperature needs CuO/Al to ingnite? Would be good to add some sulfur to the CuO/Al mix so it can be ingnited easy or it will slow down the burn rate? Also i had a thought to add some kno3 to make it more ingnitable will this work?
Oh and a last one, Carbon reduces CuO at low temperatures could be used as fuell?

plz someone anser!!:(

Polverone - 2-11-2002 at 11:37

In what proportions did you mix the aluminum flake with the copper oxide? They should be in a stoichiometric ratio for best results. If you're not sure what a stoichiometric ratio is, see my earlier advice about acquiring some chemistry books. A good igniter mixture is powdered aluminum and sulfur, again in a stoichiometric ratio (or somewhat off of such a ratio if you want it to burn slower). I don't think you'll improve your CuO/Al mixture any by adding carbon, sulfur, or potassium nitrate. BTW, if you can get 600 mesh aluminum, why do you have to resort to electrolysis to get copper oxide? You should be able to get it cheaply from a pyrotechnic or ceramic supplier.

bonemachine - 3-11-2002 at 01:39

I mix them in equal volumetric parts (i don't have a scale). There is no ceramics where i live wich sell CuO but Al powder i can find easy in hardware shops. I think that barium nitrate/Fe fuse burned hot like the S/Al mix but it didn't light. Would a kno3/Al/S mix ingnite the thermite reliably?

thanks for the reply:)

bonemachine - 3-11-2002 at 11:49

Damn i tryed again CuO/Al and it didn't worked. Just some Al sparking and then it goes of. And the yields of Cu(OH) with elctrolysis is to small. When i heat it to form CuO the volume gets even smaler!.Two days of electrolysis for a gram or 2. It is realy pain in the ass to make it that way. Guess i am never gona make it. :(
Any other sugestions to make a super fast burning thermite? I have very fine Al.

Zn instead of Al

Alchemist - 3-11-2002 at 16:40

Hello all,

just to let ya all know, CuO and powered Zinc is as reactive as CuO and Al or even a little more so. Penny's after 1982 (USA) are almost 99% Zinc. Zinc is very easily (well almost) powered in a ball mill while still warm. Zinc is also reactive with other Oxides also, but I can't find my list. Sorry I will keep looking. More late, I hope!

bonemachine - 4-11-2002 at 06:00

Actually my problem is the manufacture of sizeable amounds of CuO with starting material Cu. I manage to make some with electrolysis but all my tests (with CuO/Al) failed and i must wait to electrolise for two days to get 2 grams for another testing....

bonemachine - 4-11-2002 at 06:06

I am quite sure that i read recent that Cu2O is prepared comercialy by elctrolysis but it doesn't describe how

Cu2O is red isn't it?

Nick F - 4-11-2002 at 11:36

Cu2O is red, CuO is black.
Bonemachine, don't you have any nitric acid? Cu(NO3)2 is easily made into CuO...

PHILOU Zrealone - 13-3-2003 at 06:05

CuSO4 -heat/air-> CuO + SO3
Cu(NO3)2 -heat->CuO + NOx
NOx can be condensed as N2O4(l) to make panclastites!

Cu + H2SO4 or HNO3 --> CuSO4 or Cu(NO3)2
CuSO4 + 2NaOH --> Na2SO4 + Cu(OH)2(turquoise ppte)
(idem with Cu(NO3)2)!

CaC2 is not a burning fuel even with O2 or HNO3 it doesn't burn; don't expect it to burn with lower oxydisers like CuO!
It is made from CaO and C in electric furnace!

If your CuO/Al doesn't work maybe incriminate your Al powder; it has to be very smooth, without fats, thin oxyd layer!

A fast decomposition doesn't mean detonation!
All what goes over 350 m/s will make a strong bang!If you put a detonator on it; it will boost a bit the reaction, but it will stil not be a detonation! I have boosted many times black powders with primaries powdered all arround in the charge...it increases power and speed but it is not a detonation in the proper sense of the term!
If the burning speed is 1000m/s it is still a deflagration; it displays brisance properties!

BromicAcid - 13-7-2003 at 17:58

Speaking of silver oxides I have had some experience. Before I knew better I decided to recycle my soluble silver wastes, I precipitated them out with hydroxide to for the oxide Ag2O. I figured this would burn with a vengeance so I decided to throw in some liquid sulfur as a binder. The aluminum power, liquid sulfur, and silver oxide went together without a hitch, but when I was placing the mixture in the cast I had for it, after it cooled down a bit it started crackling and glowing red hot. Before I could toss it away the whole solidified top blew off and the mixture went up REAL fast tossing debris in the air. Not sure how the oxide would have gone up without the sulfur, it could have moderated the reaction, or it could have been the cause of it going up so quickly.

CuO and Al

chemoleo - 25-8-2003 at 17:09

elsewhere I heard that CuO and Al is one of the most powerful thermite mixtures. So I set out to make prepare it. I mixed NaOH ( in solution ) and CuSO4 in stoichiometric amounts, and washed the bright blue Cu(OH)2 precipitate many times to make sure no Na2So4 is left. trust me, none was left :)
This i dried in the sun, and heated it to at least 300 deg C under a bunsen flame. the powder turned black, and its propertiers are a bit like activated charcoal (i.e. nearly like a liquid - quite cool to look at)
This I mixed with Al (0.2 mm or less), and ignited as usual with a few sparkling candles tied togetha. It worked fine, but about as vigorous (or probably less) as the standard Fe2O3/Al mixture. Couldnt see any difference between the two. any idea why it is not as vigorous as some say, in this thread????

[Edited on 26-8-2003 by chemoleo]

vigor

Polverone - 25-8-2003 at 18:45

I was using aluminum powder (300 mesh) instead of granular Al. I'm sure that makes quite a difference.

chemoleo - 25-8-2003 at 19:41

sure, but then, I used the same Al for the Al/Fe2O3. so the differnce should be relative. and i didnt notice any relative difference :(
but maybe that type of reasoning doesnt hold here...

Cu2O and Al

chemoleo - 19-9-2003 at 04:56

Recently tried some Cu2O (commercial, from potters supplies) and Al (200 mesh). This uses a very large amount of Cu2O, I found (about 200 g total).
Anyway, the reaction (after ignition with sparkling candles was very slow), emitting large amounts of smoke (orange-ish, like a smoke flare), and taking quite some time - so good for presentation purposes :).
After the reaction, I obtained a large block of solid copper, which, upon cooling, forms concentric rings of rainbow colours (this hast gone into my arts collection :) )

vulture - 4-11-2003 at 07:12

A mixture of a reactive metal in the elemental state and a more noble metal in an oxidized state is a thermite mixture.

The reactive metal reduces the noble metal to it's elemental state, whereas the reactive metal is being oxidized (mostly to its oxide).

alchemist_fire - 11-11-2003 at 09:24

here is an easy one that I figured out by accident 2:1 magnesium to lead dioxide from car battries the reaction is explosive and if you you fill a small aspirin bottle with this powder and stick a nice fuse into the powder it makes a very nice loud explosion

Thermites with CuO, MnO2 and Fe3O4

chemoleo - 15-12-2003 at 15:22

Some updates on exotic thermites:

I recently purchased some CuO, MnO2 and Fe3O4 (and others, but didnt get round to testing them).

Using 200 mesh Al, I found CuO to be by far the most vigorous. It is set off by mere sparks (be careful, I nearly got my ass burned), and burns (unconfined) with a great whoosh type sound, and vaporises all the products, i.e. no residue is left. Burning time is too short to measure. On the video camera it happens within a few frames. Will test this on occasion in a confined manner. Anyway, i tried the same with homemade CuO, and the results were by far not as vigorous... I am still struggling to explain why, after all I used clean reagents, and heated the homemade CuO to a dull red glow....

The MnO2 is hard to set off (compared to the CuO), but the reaction is also very fast, and leaves very little residue. But by no means it can be compared to the CuO. I was hoping MnO2 would be very powerful as it is an oxidiser in itself (I know, nearly every oxide is with respect to Al, but it's definitely a strong oxidant ), but still it doesnt compare at all to CuO... It's only a little faster than with Fe2O3.

Fe3O4 was the slowest, the reaction took up to 15 seconds, with lots of sparks/molten metal globules spraying everywhere, it looks very pretty but is not very vigorous. Definitely top choice for showing a nice pyro effect.

I have a few more to test, which is NiO, Sb2O3, V2O5, Cr2O3 and ZrSiO4... where I am not sure the latter will work :( - but always wanted to lay my hands on some zirconium!


[Edited on 15-12-2003 by chemoleo]

Theoretic - 16-12-2003 at 01:34

Just an interesting fact: Fe/Fe2O3 releases more energy per gram (upon conversion to FeO) than CuO/Zn!

chemoleo - 16-12-2003 at 02:42

maybe so, but that's definitely not the case with Al!! :D:D

Quantum - 16-12-2003 at 13:05

Can anyone explain the reaction between Al and S? There is not any oxygen present so I would think the heat oxidises one of those and then they react. Not sure thought.

vulture - 16-12-2003 at 13:15

S can act as an oxidizer. An oxidizer is a substance that can increase the oxidation number of other compounds, by decreasing it's own.

In this case, the S will be reduced to S 2- and the Al oxidized to Al 3+.

CuO homemade vs 'store bought'

Mr. Wizard - 16-12-2003 at 20:32

Maybe Chemoleo's 'drying' of his home made CuO at a red heat, had converted some of it to the Cuprous Oxide? If he heated it in an oxygen atmosphere wouldn't it stay at the higher oxidized state?

[Edited on 17-12-2003 by Mr. Wizard]

[Edited on 17-12-2003 by Mr. Wizard]

Theoretic - 17-12-2003 at 01:37

Chemoleo:
Hell, no! :o:o:o
Fe3+ => Fe2+ has a higher potential than Cu2+ => Cu! Not Fe3+ => Fe though, :D:D:D.

chemoleo - 17-12-2003 at 07:05

Theoretic:
what are you getting at? Per gram of Al, the oxidation to Al2O3 is surely releasing more energy than with Fe or Cu, as the main factor limiting this is the atomic mass (moles per gram) of the metal. That's all I suggested, so pls don't write posts on different issues putting it as if I was talking bollocks :o:o

Mr Wizard - I doubt it. Cu2O should oxidise to CuO in an oxygen atmosphere, under such conditions. Anyway, dissolving the homemade CuO in HCl produced green CuCl2 only, and no white precipitate which would indicate the presence of Cu(I)Cl!
I think I will one day try to obtain CuO by different means, i.e. not by the hydroxide/heat method

[Edited on 17-12-2003 by chemoleo]

Theoretic - 17-12-2003 at 07:48

Chemoleo:
Sorry, I thought that you were talking about Al2O3 as a fuel in Fe2O3 and CuO thermites.
You want to use methods other than the hydroxide method for CuO? Can't think of any ones apart from heating copper nitrate and copper sulfate, both of which produce nasty fumes.

KABOOOM(pyrojustforfun) - 19-12-2003 at 21:21

yeah nasty but I wouldn't use such disapproving word for (holy) SO3:o
got some sodium dichromate lately. may try CrO<sub>3</sub>-Zn. CrO<sub>3</sub> is a little scary but not that much (?) I think it's OK as far as I don't let it touch org matters

chemoleo - 20-12-2003 at 10:21

haha... I was thinking on the lines of CrO5 (a beautiful blue compound), however! I bet that explodes/reacts very violently upon touching a metal such as Al!

Sparky - 20-12-2003 at 12:07

IIRC copper carbonate will decompose to CuO and carbon dioxide with heating. Copper carbonate is also available from many pottery suppliers BTW. If you bother going to a ceramics store then I suppose you might as well get CuO though.

Chemeoleo, you describe your home made CuO as quite bulky and free flowing, right (flows almost like a liquid)? I think this may be why it doesn't work as well as the more dense, store bought stuff. I think all thermite like reactions, including CuO/Al, are solid state, compared to the gaseous state of most pyrotechnic compositions. This means that there is no gasseous flame front to travel between the particles, but rather that the particles must pretty much be touching to react. The result is that if you bulk up a thermite composition, it will burn slower. If you pack it down it should burn faster.

To test this you could take some of your CuO/Al mix with home made oxide. Pack it carefully into a tube, then compare it to mix using commercial stuff, packed to the same density.

WoW!

chemoleo - 20-12-2003 at 13:41

This is great stuff!!!
It gives gas volume, cal/g or cm3 etc etc, temperatures for every thermite reaction imaginable, plus many more reactions!!

Check where Al/MnO2/CuO/PbO2 sits!

Do you have some more data files like this?

Edit: Sparky, I agree it's a parameter, but I try to maximise density for any pyro mix.. i dont think that was the reason anyhow. Yes, I think I will make some CuCO3 (this is what I had in mind originally, referring to Theoretic's post), and heat it until it turns thoroughly black. Will test this again. It did baffle me as you can see! :(

[Edited on 21-12-2003 by chemoleo]

KABOOOM(pyrojustforfun) - 3-1-2004 at 19:31

the file HAS BECOME corrupted. something's going wrong with the attached zip files (?) ...

Mad Science Thermites :D

chemoleo - 26-1-2004 at 16:48

Well, I did some interesting, but slightly mad stuff yesterday.
It turned out I had quite a bit of silicon (the paste type for sealing things) lying about, so the decision was made to burn it. It burns not great, but once it does, it develops lots of white smoke and leaves a grey white substance - whcih is carbon (& derivatives)-contaminated SiO2 I speculated.
So I went about testing this :) . The residue from the burnt silicone was crushed, and mixed with an estimated, not weighed amount of Al 200 mesh. It was started with a film capsule full of NaClO3/Al. After the initial flash of light from the NaClO3/Al, the silicone burn product/Al indeed started to glow a bright white glare, the reaction took several minutes to subside! Chunks formed, which glowed bright white and could be separated from the rest!
Today I looked at one of those chunks, they turned black/brown that crumble easily... Nonetheless purifcation of pure silicone shouldnt be easy, my textbook states that boiling in conc. HF is necessary :(
Nonetheless, cool experiment isnt it? ;)

Actually some liquid silicone was mixed with Al powder, and then allowed to harden. I was hoping of course that once I wuld light it, the resultign SiO2 would react with the Al, make a thermite paste of sorts :) - but sadly, although this burned better, no thermite reaction occurred.

The second one involved ammoniumdichromate. This was alighted, and the resulting extremely voluminous Cr2O3 was used for a thermite reaction, with Al again. It works very nicely, and produces a solid product where no free Cr could be found. In fact it completely maintained the shape of the plastic cup in which it was ignited (even though it was glowing white for at least a minute)... was thinking that this could have all sorts of useful purposes!!

Anyway, i think it's time to purchase some fine quartz sand from pet shops etc, and see how the real SiO2 works!

Edit: Post No 300 in the true mad science way :D:D

PS what happened to Adiabatic? The guy who posted this thermite reactions file? His post completely disappeared!?!

[Edited on 27-1-2004 by chemoleo]

hodges - 26-1-2004 at 17:28

Quote:
Originally posted by chemoleo
The second one involved ammoniumdichromate. This was alighted, and the resulting extremely voluminous Cr2O3 was used for a thermite reaction, with Al again. It works very nicely, and produces a solid product where no free Cr could be found.

I don't quite get it. Are you saying the product was something besides Cr itself?
Quote:

Anyway, i think it's time to purchase some fine quartz sand from pet shops etc, and see how the real SiO2 works!

If you have water glass (sodium silicate solution), you can also precipitate fine SiO2 by adding some HCl or other acid, then rinse and dry. Kind of an expensive way of making sand, but it is pure and fine that way.

I've tried a couple of thermites myself recently. I've made iron oxide in a couple different ways (using FeCl2 and FeCl3) and mixed with aluminum in the appropriate proportions. Actually, the mixture made with iron (2) oxide seemed to react the fastest.

I made some CuO and made some thermite using that. Although the reaction was pretty fast, I didn't get a flash or a large plume of Cu vapor (I only used 1g total of the thermite). I did find a small ball of solid Cu. Maybe my CuO wasn't completely dry, although I did heat it at 200C for about an hour after all the water was gone.

I made some thermite using ZnO and Al as well. This is kind of weird stuff. It sort of glows for a while, then suddently flashed up with a green flame, then glows for a while and flashes again. Very little Zn was produced - I'm thinking it either vaporized or else burned in the air as soon as it was formed. There was however a thin coat of Zn on the metal ignited it on. Probably condensed vapor.

I tired a mixture of CaSO4 and Al. With hydrated CaSO4, the reaction is fairly fast. When I dry the CaSO4 first, it is like a flash powder. I expected to get maybe CaS but treating the residue with water produced no gas. My guess is it went all the way to CaO.

I've tried a couple of different ways of igniting the thermite mixtures. Keep in mind that I am doing this in my sink inside so I am using small amounts (about 1g) and I don't want something that produces a lot of SO2 or other irritating gases. The best thing I have found for igniting is a small amount of fine Al powder and S. This ignites reliably with a "fuse" made of string soaked in KNO3, and it always sets off the thermite (even the CaSO4 mixture). Very simple, and doesn't produce much in the way of fumes as long as I don't let the Al2S3 sit too long before disposing of it down the drain. I tried a sugar/KNO3 mix and it lit with the string fuse but would not reliably ignite the thermite (even iron/aluminum). I tried a thin nichrome wire heated with a battery, and this was not reliable either unless I used it to first ignite the Al/S mix. Magnesium ribbon works most of the time but is hard to light even with a butane torch and I'm afraid I will light the thermite in the process of trying to get the Mg to light so I don't usually use this method.

Hodges

Zn thermite

FrKoNaLeaSh101 - 27-1-2004 at 15:34

I recently came into contact with 11lbs of 625 mesh Zinc powder and i have some MnO2 and can make some Red Iron Oxide....I was just wondering if any of u knew and stoichiometric ratios for either of those mixes. any help is greatly appreciated

hodges - 27-1-2004 at 18:40

Quote:
Originally posted by FrKoNaLeaSh101
I recently came into contact with 11lbs of 625 mesh Zinc powder and i have some MnO2 and can make some Red Iron Oxide....I was just wondering if any of u knew and stoichiometric ratios for either of those mixes. any help is greatly appreciated


Using the zinc in place of the aluminum, I assume? Let's see.

Fe2O3 + 3Zn --> 2Fe + 3ZnO
160 195
That would be 160 parts Fe2O3 to 195 parts Zn, or roughly a 4 to 5 ratio of Fe2O3 to Zn.


MnO2 + 2Zn --> Mn + 2 ZnO
87 130
87 parts of MnO2 to 130 parts Zn, or roughly 3 to 4 ratio of MnO2 to Zn.

I did some energy calculations - may or may not be right so I won't show them here. But if they are right, I show only 150 calories per gram for the Fe2O3 mixture and 195 calories per gram for the MnO2. By contrast, the standard thermite Fe2O3/Al reaction yields 930 calories per gram. My ZnO/Al mixture burned rather poorly and it yields 488 calories per gram. So unless my calculations are wrong, my guess is using zinc in place of aluminum is not going to work very well.

But its worth a try to see what happens. Always use small amounts and stay well back until you have seen what a new reaction does.

Hodges

thank you

FrKoNaLeaSh101 - 27-1-2004 at 20:25

omg u are the best thank you so much.....i am not the best at stoichiometry yet i am not learnign it till next week in chem class.......and no one on totse knows anything like that so thanks

and also i am not exactly looking for an insane reaction....i have never seen any thermite to compare it to except a pic in my textbook. so i will try both and report back what i find....also i do have 11 pounds of Zn to use...so i might as well experiment

[Edited on 28-1-2004 by FrKoNaLeaSh101]

I don't think this worked

hodges - 29-1-2004 at 20:03

Tried making thermite with SiO2 and Al. I have heard that this works. I took 0.5g of fine play sand ("asbestos-free";) and 0.3g of pyro grade Al powder. Attempted to ignite with a mixture of 0.3g S and 0.3g of the Al powder (this ignition always works for other thermites, and even works when using CaSO4/Al). It did not ignite. BTW, I know the proportions are not right for the Al/S. I use excess Al to prevent SO2 from being formed since I'm doing this inside.

So I tried mixing some of the aluminum/sulfur mix in with another batch of the SiO2/Al thermite. This time the mixture did burn, though rather slowly.

When cool I added a few drops of 3M H2SO4. I expected the production of silane, which burns spontaneously in air, from the aluminum silicide that is formed as one of the products of the reaction. But I got no flames or pops - only some H2S. Then I added a bit of water and let the Al2S3 react. Once the reaction stopped, I added more dilute H2SO4. Again, just a few more bubbles of H2S. The resulting solution was black, not brown like I would expect for silicon.

Has anyone else here gotten this to work? I've seen several posts on Usenet where people claim to produce Si using this reaction.

Hodges

KABOOOM(pyrojustforfun) - 30-1-2004 at 13:41

<blockquote>quote:<hr>I expected to get maybe CaS but treating the residue with water produced no gas. My guess is it went all the way to CaO.<hr></blockquote>
the realy realy hot CaS dispersed in air couldn't survive and probably "burnt" to produce chalk....

btw anhydrous C<b>u</b>SO<sub>4</sub>-Al and PbSO<sub>4</sub>-Al should make pretty violent thermites. not something to do in your kitchen specially the last one :P
3CuSO<sub>4</sub> + 10Al <s>&nbsp;&nbsp;&nbsp;></s> 3Cu + Al<sub>2</sub>S<sub>3</sub> + 4Al<sub>2</sub>O<sub>3</sub>

Success! (SiO2 Thermite)

hodges - 7-2-2004 at 16:08

I found out that the problem with the SiO2/Mg thermite was that the sand I was using had too large of a grain size. I was able to find some 200 mesh "silica", and was successful with this.

I mixed 1.2 grams of SiO2 and 1 gram of powdered Mg. I ignited this with a small amount of Al/S mix. It glowed red hot for almost a minute. When it cooled, I dropped a small amount in dilute HCl. I thought I heard a couple of pops, then I definitely saw a small spark on top of the solution and heard a small pop. I then dumped in the entire product into the HCl. For a second or two, it sounded like firecrackers going off (though not as loud). There were numerous flashes of flame. After that there continued to be pops and flashes every few seconds for a couple minutes.

I washed the resulting product and crushed it up. Presumably it is impure Si. It has a color between gray and tan and looks a lot like mud. When viewed from the outside of the glass measuring cup a metalic shine is aparent where the surface is in contact with the glass.

I took some videos and may post still shots of the reaction and products sometime depending how the still frames look once I digitize them.

Hodges

magnisium oxide?

chewyguy2005 - 11-3-2004 at 19:14

Would it be possible to create a thermite from magnesium oxide and aluminum yielding magnesium?

vulture - 12-3-2004 at 08:30

Yes, but you would get vaporized magnesium in the reaction flame.....

Check the boiling point of Mg...

t_Pyro - 12-3-2004 at 09:55

Quote:
Originally posted by vulture
Yes, but you would get vaporized magnesium in the reaction flame.....


Are you sure? The reduction potential of Mg<sup>2+</sup>|Mg is -2.37V while the reduction potential of Al<sup>3+</sup>|Al is -1.66V Hence, aluminium will not be able to reduce magnesium oxide. Oxides of metals only <i>below</i> aluminium in the electropositivity series will work in thermite mixtures. And the melting point of Mg is 650<sup>o</sup>C.

[Edited on 12-3-2004 by t_Pyro]

hodges - 12-3-2004 at 15:23

Quote:
Originally posted by t_Pyro
The reduction potential of Mg<sup>2+</sup>|Mg is -2.37V while the reduction potential of Al<sup>3+</sup>|Al is -1.66V Hence, aluminium will not be able to reduce magnesium oxide. Oxides of metals only <i>below</i> aluminium in the electropositivity series will work in thermite mixtures.


Actually, it is the heat of formation, and not the reduction potential, that will determine if a thermite mixture will work. Aluminum is able to reduce K2O to potassium even though potassium has a larger reduction potential. But the aluminum loses 3 moles of electrons, whereas the potassium only gains one. Thus that reaction end up being slightly exothermic, and will proceed. OTOH, the reaction between MgO and Al is endothermic if you work out the energies involved. So you are correct that this reaction will not proceed (at least not without adding heat). The reverse reaction (Al2O3 and Mg) theoretically could be used to prepare Al, although the difference in heats of formation is small enough that the reaction might not be self-sustaining.

t_Pyro - 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]

Thread

hodges - 13-3-2004 at 15:33

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.

Exotic Thermites

RogerP - 1-4-2004 at 10:10

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.

chemoleo - 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?

The_Davster - 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]

exotic thermite

Lestat - 1-5-2004 at 00:46

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...

Axt - 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!

Thermodynamics of thermites AND CaSO4/Al

chemoleo - 31-5-2004 at 16:57

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!

Axt - 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]

The_Davster - 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.

Lithium thermite

Saerynide - 21-7-2004 at 22:41

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?

The_Davster - 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?;)

Saerynide - 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]

Darkfire - 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.

Saerynide - 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) :(

The_Davster - 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]

Saerynide - 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.

The_Davster - 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.

Saerynide - 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]

darkflame89 - 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?

Saerynide - 23-7-2004 at 05:39

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

IPN - 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. :(

Saerynide - 23-7-2004 at 06:03

The burning paper set off the MnO2 mix? :o

chemoleo - 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]

Axt - 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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