Psychedelic Physicist
New Member
Posts: 5
From: Australia
Registered: MAY 2001
posted 05-16-2001 06:17 AM
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Hi, could 2 parts iron oxide be mixed with 1 part titanium to make thermite and could 2 parts magnesium dixide be mixed with 1 part titanium as well?
Thanks for your help.PP.



J
Moderator
Posts: 602
From: United Kingdom
Registered: SEP 2000
posted 05-16-2001 06:51 AM
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This should have been posted under the existing thermite thread, where your first question is answered. As for your second question, assuming you mean MgO (Magnesium Oxide), you would have incredible difficulty igniting the mix since MgO has a melting point of almost 3000 degrees C.
J

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"If the aquarium water has to be drunk don't waste the fish. In fact they'll probably be the easiest to eat even if you don't need the water. The cat is next in the pot." - John 'Lofty' Wiseman



Gollum
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Posts: 92
From:
Registered: DEC 2000
posted 05-16-2001 03:29 PM
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Iron oxide mixed with aluminum is the standard for thermite. And to ignite it usually magnesium dust and sugar will do, but sometimes sparklers can get thermite going without any extras. Just hope you're wearing gloves cuz this stuff spits like a mofo. And use the search function!


PYRO500
Moderator
Posts: 1465
From: somewhere in florida
Registered: SEP 2000
posted 05-16-2001 04:35 PM
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wrong fucking thread, transfering...


kingspaz
Frequent Poster
Posts: 347
From: UK
Registered: SEP 2000
posted 05-16-2001 05:29 PM
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don't thermite mixtures depend upon the different reactivities of metals?
the reason MgO and Ti (is that right the symbol for titanium?)will not work is because magnesium is more reactive than titanium therefore the titanium can't take the oxygen from the magnesium. so i think a good mixture would be copper oxide and magnesium
i think thats right....can someone correct me if i'm wrong please


PYRO500
Moderator
Posts: 1465
From: somewhere in florida
Registered: SEP 2000
posted 05-16-2001 06:08 PM
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thermite by def. is aluminum powder mixed with a metallic oxide


Psychedelic Physicist
New Member
Posts: 5
From: Australia
Registered: MAY 2001
posted 05-17-2001 02:10 AM
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Thanks for your help, i have only made two posts so i'm not that sure about the rules and i did a search about thermite but i didn't know if the ratios were still the same for diffrent chemicals. I didn't know to post this under an existing threed because i haven't been here long so try to put up with mistakes please. This fourm is the best everyone seems to know heaps (from what i've seen) and are realy keen on saftey.
Thanks.PP.

I'm considering doing a research project on thermite, the classic recipe (FeO/AL)

Specifically, I'm wondering what kind of addititves could be thrown into the mix to get a higher temperature, lower activation energy, longer duration, or what out of the reaction.

I'll conduct a patent search some day soon.

I was just looking for some input.

I did some forum searching,
apparently you can add plaster of paris, 15% or so to make thermite castable, thanks FragM,

Nice uniform thermite bits.

Perhaps this could be used in making an improvised incendiary gravity bomb. Each one a section of a ring, with thermite leading to the center, with a burster charge at the core? The rings would be stacked to form a typical bomb shape, with some metal fins in the rear of a thin metal housing holding the whole thing together. A burning fuse of KN03/sugar or something in a Pixie stick would have to be set at the end when it is dropped or left on some poor fucker's roof. Heh. Just a thought.


Oh, apparently 4/1 thermite to KN03 works pretty well. DarkAngel didn't say exactly what benefit it provided, but i'm assuming the KNO3, a good oxidizer, increased the burn rate significantly.

As an incendiary, this might be a bad thing. The longer it stays on fire, the better it would ignite flammable materials. Although in cases where i'd want to set something on fire, I'd use napalm.

As a means of burning through things such as the engine block of a car or something, a higher burn rate, thus higher temperature, might be a desireable property.

You know, thermite is not the wonder substance it is supposed to be. It barely makes an impression on thick metal blocks, especially those with high melting points. I'm guessing this is because the metal just conducts the heat away too fast.

As an incendary, it can be very effective. I lit a small amount in my room back 'in the day', and it spat loads of tiny iron balls everywhere that set fire to everything. Those little balls don't stay red hot for very long though, so a fire would have to become self sustaining in a short period of time. As for destroying roofs, I don't think roof felt is very flammable.

I have heard, never tested, but heard, that adding a small percentage of sulphur to the thermite mix makes it easier to ignite, in the same way that sulphur sensetises TNT. However, I don't know if the presence of sulphur in the mix would increase the burn rate.

A fast burn rate does not nescessarily mean that thermite would be better at melting stuff than if it burned slower. I would think the opposite. If it all burns really fast, the reaction is over and no more heat is produced very fast. If the burn rate was slower, but still hot, (as it obviously would be), then the high temperature could be sustained for longer, meaning more heat would be transferred to the metal to melt.

Therefore, I recommend using manganese dioxide as the oxidiser in thermite, as it burns more steadily than iron oxide based thermite. It spits less, too.

Sulfur, ay? I'll have to try that, with and without the plaster of paris. The use of Fe0 is really dictated by it's availability. If I get my hands on some MnO2, I'll use it.

Apparently manganese dioxide is present in dry cell batteries. It is not in pure form though, needs to be processed a bit. Although I remember that acids are used somewhere in the purification process, the specifics of the process have escaped me. Might give you something to go on though.

I remember that to obtain the impure manganese dioxide, you cut open a dry cell battery and you should find a load of black stuff crammed in there. That's what you need to work with. I'll see if I can find information on the specifics of this process, I found it once, so I should be able to rake it out again.

Holy shit, I KNEW that, the bit about mno2 and batteries, but completely slipped my mind. Good call, Sonny Jim. if you can find that proccess, it'd rock.

I have a bottle of Titanium metal in my room. Anyone see a use for it? Would it burn any hotter than Al in a composition?

'Produces bright sparks when small amounts are added to pyrotechnic mixtures. Adds a long-lasting, bright spark effect to many firework formulas'

That's what titanium metal is said to be used for in pyrotechnics. That particular quote came from www.unitednuclear.com . I've never ordered from them, because it seems really expensive, but their chemicals page http://www.unitednuclear.com/chem.htm is a useful reference point if you are after a brief description of a chemical's use.

Good to hear the MnO2 information was useful. I'll try to find that purification method for you.

Titanium has the second highest flame temperature of all metals, the only metal that surpasses it is Zirconium. And Zr/O2 burns at 4660C....

The titanium does not to be a fine powder however, otherwise it is pretty oxidation resistant.

Titanium is the only element that'll burn in pure nitrogen, apparently. I think I read that at webelements.com.
But I wouldn't waste it in incendiaries, it's way too neat for that. Think about it, using MnO2 instead of iron oxides, or Ti instead of Al, is going to increase the cost by at least ten times I would have thought. So, for half the price you could make five times more "traditional" thermit, which will be vastly more effective.

That's a good point, but I like MnO2 thermite as it doesnt spit as much as the traditional variety, and has a steadier burn rate. I think it's just fun sometimes though also just to try a less practical option once just to see if it will work, for the sake of curiosity.

Oh yeah, it's good and fun to experiment, but I wouldn't actually use it for something practical, unless it had definite advantages that outweighed the reduced effectiveness per �, is what I was trying to say.

Be sure to find the nearest ceramics suppliers to you, and check out their selection of metal oxides...

Anyone here tried the CuO + Al thermite?

Its supposed to be explosive when the components are finely powdered. I can believe it too judging by the differences of Cu from Al in terms of electronegativity. Lead is only slightly lower and is pretty potent when used in the dragons eggs formula (MgAl/Pb3O4/CuO/binder). Anyone had explosive success with this mix?

Well, I am using frequently Pb3O4/Al mix as a good-for-all mixture. It's not THAT sensitive but it explodes if confined with a great violence. It burns instantly. So, Mg should make it flame sensitive (dragon eggs).

I also tried MnO2/Al mixture in order to isolate manganese metal, and it's somewhat faster than Fe oxide thermite, but is not that hot.

An interesting mix is plaster of Paris/Al mix (discussed here before aswell)

There is a good thread here (http://www.sciencemadness.org/talk/viewthread.php?tid=127) concerning these exotic thermites.

Well, I hope to do a more exhaustive study of those exotic thermites, although I may confine my research to variations on classic thermite. Given the higher burning temp of Ti, would that mean a Ti thermite would burn at closer to that temp?

The titanium I have is a freebie, and right now it's just a paperweight. A metallurgist ex-bf of my stepmoms gave it to me for reasons I can no longer remember. It is currently a pretty finely grained powder. I had a small amount of VERY finely perfectly spherical Ti, but god knows where it went.

Arm: At some point, when I'm less broke, I'll try that CuO/Al mix. I think at this point, (considering I'm pretty damn broke) my project will remain at the information gathering stage.

Mr. Cool: Earlier in the thread, the Mn02 option was discussed. Sonny Jim was saying it's in dry cells, and is trying to find a refinement proccess, so the cost for Mn02 could be comparitively less. I wouldn't really be discussing Ti if I didn't have a jar of it.

The Lead Tetraoxide/Al one is quite interesting.

Apparently it is so violent because the Lead Tetraoxide acts as a vapour phase oxidiser. It vapourises in the heat of the initial reaction and the vapours in turn react with the magnalium on surface contact. With your oxidiser as a vapour you have very good final incorporation of the composition. Also, the mix supposedly has a kind of negative critical mass whereby, when a certain volume/mass is exceeded the mix no longer explodes but instead burns.

Still, Pb3O4 is pretty fucking poisonous stuff.

Lead tetraoxide is extremly unsoluble in water, and unless eaten I don't think is that "fucking poisonous". I had worked with it for years, and still no saturnism signs... People are scared unless they REALLY handle the stuff. I handled WP, so I know the dangers involved (I saw how easy it takes fire, but I didn't ate it). I handled several other dangerous chems (bromine, HF, etc). For instance, NBK2000 handled cyanide so he is not scared to do it again.

The stuff is an accumulative neurotoxin. Signs of damage can show up very many years after exposure. Solubility is not a sure-fire measure of toxicity - Pb3O4 is absorbed through the skin. Things that dont dissolve in water very well can dissolve in fat very nicely.

Please dont tell me you work unprotected from airborn dusts and skin contact.

I'm no expert, and have made mistakes in the past, but I think that I am 100% right in saying that you should never become too comfortable with handling dangerous materials.

Yeah, a lot of stuff is like that. Unless you really fuck up, you don't die or even show signs right away.

It's always good to take precautions.

Just my two cents. I wouldn't play with lead compounds without some protection. Hey, it offed the Romans .

Of course I work with gloves. Lead tends to replace Ca in bones; and yes, you can never be too confortable when handling dangerous chemicals. But this is not a reason not to use lead tetraoxide; it's cheap, it can be synthesized easily, and the results are spectacular. Using proper protection measures of course.

ARM,

i beleive i have some of that CuO Al thermite you mentioned (about 2 kilo of it)
my friend got me 2 plastic boxes full of it, in each box comes 8 plastic tubes that open up eack end, in the on end with the black cap contains the thermite, the other end with the red cap contains a bout a T`spoon of very fine metalic powder (looks a bit like flash) and in the box come a little bag with tiny metal caps like beer bottle tops. the instuctionas are in German tho :(

apparently it`s used for joining railway tracks, i`ve used a box full so far and it`s very feirce and will even when ignited burn under water with an eery orange glow.

the thermite itself is quite course, and on breaking it down with acid (sulphuric) it generates alot of heat and leave copper particles at the bottom, the fine silvery specs i don`t know what they are though? and i can`t seem to destroy them so i`m left with the pure copper.

when i can figure out how to post pics on here, i`ll show you some test results with pleasure.
also when putting a NIB magnet in the thermite powder it only pics up the tinyest amount of magnetic particles maybe half a T`spoon in 2 killos worth, if that helps at all.

as for it being dangerous tho, i suspect that the large particle size renders it somewhat more stable, the most dangerous thing i did with it was try to cast it, inside a magnetic feild (before i knew it was copper based) i used the ceramic ring magnet form a magnetron, the heat shatered the ceramic easily and the manget expolded sending molten metal everywhere, fortunately the wife was out and didn`t see it else that would be another banned experiment!

yt2095, if your thermite is intended for welding railway tracks, it contains Fe2O3 instead of CuO. Fe2O3 is not atracted by the magnet. It may contain some impurities though which are.

as i would have thought also, being as the tracks are made of steel.

but i can assure you without a doubt, this is copper based, and more than cappable of melting steel. yes i realise the temp difference makes it sound odd, but i`ve done it and have pics.
if ignited on cement and allowed to cool, a magnet will still not atract to it and it has a copper/brass like color closer to copper though.
my 1`st test was about half a cup full in a small Tuna fish can on a plantpot full of sand, it melted clean through the can and little of the sand, that then had mild magnetic properties, the NIB magnet would stick to IT, but the magnet wouldn`t pick up the mass of new metal.

the acid decomp of the raw thermite shows clearly the copper, and will also gice same copper colors on a borax bead test and also make sulphate and hydroxides of copper, there`s no iron, only as a minor impurity

i still have one of the blue boxes it came in, also re my last post, it`s 10 tubes per box, not 8.
it says on it "soldadura aluminote`rmica 10 cartuchos tipo" ??? what ever that means?
i do English and Russian only, the rest is all double dutch to me :)

embossed in the plastic case is: K|L|K then under it is "SOLDAL"

i don`t know if that`s at all helpfull in anyway, but yes, it is most deffinately a copper based thermite or something similar.

You said there was some text in German on it? Post it. I can read German and we have quite some members from Germany here.

When i've heard of CuO/Al being used in an explosive fashion, it explodes like flash leaving a brown cloud of condensing copper vapours. CuO/Al thermite does have industrial uses, but i've only heard of it being used to weld copper metal (logically). I've only heard of Iron oxide being used in welding steel rails.

I suppose rail tracks could be joined with a braze rather than a weld?

What they do, is lie the tracks down in the right place, then place a stove type object over them with the thermite inside. You know, how the plant pot demo works, but on a larger scale over two unjoined railway tracks. If memory serves, they ignite the thermite via the KMnO4 and glycerine mwthod, and it burns to produce the molten iron, that spills into the space between the two tracks to be joined, welding them together. Then, they just move the stove and fuel it up again for the next join. I guess it saves on equipment that would be needed for brazing, and means the join is of iron, and not some weaker metal.

I remember seeing this on a science video at school (which I have just left, YAY). Footage of it and everything. Well, I suppose its only typical skinflintedness so common in comprehensive schools. I'd guess a video is cheaper than a demo in the lab.

Vulture,

The documentation has long since gone, as have most of the plastic tubes (i used them for flash salutes)
the only thing remaining is one of the blue boxes that i now use to put pens and pencils in.
and the thermite is in a big jar with the ignition powder in a small medice bottle taped to the jar so i don`t lose it
all thats writen on the box was typed in my last post. i was told a few years ago that the Documentation was in German, since i can`t read or speak german i took my friends word for it, needless to say it was about as usefull as a chocolate fireguard to me and so ended up in the trash can. hardly usefull to you now, and posting you some thermite would be out the question!
as for welding tracks, i can see how it would work and certainly fuze them together, but i can think of better thermite mixes that would be alot stronger than something copper based, but then i`m no railway engineer either :)
when i can figure how to post pics on here without messing things up for anyone, be sure, i shall do this, mean time, has anyone got any ideas other the the ones i`ve already done, to establish exactly what the composition is, and possibly ratios would be nice but not necesary?
also as i have just a fraction over a kilo, has anyone got any ideas as wether of not it`s possible to cast the molten metal into something usefull, i considered wet sand that had been allowed to dry with a wodden copy of what i want casting and letting the sand dry then filling the void with thermite, i`m sure there`s better methods or materials though.
of this i will also take pics.

Arm, as for the brown cloud, i wouldn`t know in all honesty, i`ve only ever used it at night, but logicaly i would assume that it would do this also.

all the best, and thank you for your offers, i`ll know where and who to ask if i get anything else interesting with different language documants in it :)

BINGO!

my thermite mystery`s solved :)
yes it is Copper based, but it`s Bronze thermite, not copper Alu (as i assumed as i`de never heard of anything else as a reducer in a thermite reaction)
the reactant is Zinc so i`ve been told on the fone just seconds ago.

of course now all i need to do is isolate the copper, get some Alu powder then... :)

thank you all for your patients/help :)
i knew we`de get there in the end!

The reason that many people are disappointed with the results of thermite is that they fail to use a coffer damn. Most just use built up sand around what they are trying to burn through. I have heard of pre-fabricated ones, although I am unsure what they are made of. The pooling action of thermite grenades GREATLY aids in the penetration of metals, ie the skin of a MK84 or an engine block (if thats what your into). :D

to be honest, i`m not into destruction at all, tho i do like to blow up the odd faulty hard drive or 2 :)
i think the most destructive thing i`ve done with the thermite is melt a tuna can, or used it to start a pit BBQ on a beach.
since i have quite a large quantity of it (by my standards) i`de like to make something useful with it, maybe cast some numbers for my front door, or an interesting paper weight or ashtray.
i`m sure others may think it a waste or a lame thing to do and would sooner burn a car, but that`s not my mojo.

i`ll try that dam idea and make it on a slope so the liquid will pour into my mold rather than risk destroying my shape with the violent reaction.

Cheers `n` beers :)

cameroneod define"coffer" are you talking about a clay funnel or what. since i have not used thermite iam neither impressed or depressed by its preformance, although i saw NBK's picture of cast thermite in action and it was quite amazing. but for lack of chems and lab equip to make HE's i have retired my self to pyrotechnics and the like. untill i have a place of my own to do what i want

I seem to have much better luck with thermite (Iron based) when I mix it with a little Plaster Paris. If I just burn the powder it doesn�t fully react. Anyone know of an easier way to light it than by using Mg? (And I don't have any Potassium Permanganate (KMnO3?), or know where to get any)

yt2095: �soldadura aluminotermica 10 cartuchos tipo��or similar is in Italian and it means something like �aluminothermic soldering composition 10 cartouches type��

MnO2 it is not soluble in water so it can be extracted easily from dry cells ('Leclanche" type) by simply washing the black stuff inside them with clean water and drying it. That black powder is MnO2...

I've done many tests with various types of thermite...I used to ignite them with a mixture of Al/oxidant (which can be potassium chlorate, ammonium perchlorate, potassium nitrate, barium nitrate, barium peroxide (BaO2) etc.). The mixture doesn't have to burn fast and a small part of it should be mixed with thermite (that part which is in close contact with your charge of thermite...).

Once I've made a kind of thermite with Al and vanadium pentoxide (V2O5) - this is used as a catalyst in industry - and I put about 15-20g of this thermite in a plastic container taken from some drugs. The igniting composition (described above) didn't worked but the plastic got on fire and after a minute or so the flame ignited the thermite!! The charge of thermite was pressed inside the conteiner so it kept its shape while the plastic container was burning...The thermite with V2O5 burned quietly with a bright, superb YELLOW light! Very nice indeed! I didn't see any vanadium left, anyway...

I have made a small quantity of thermite by using a nail and attaching an electrode to it in water. I dried the powder and heated it until it was rust red added aluminum shavings to it, and lit it with some magnesium ribbon. The 'thermite' did not light from the magnesium ribbon, it didn't do anything at all. My question is, what am i doing wrong? I've checked multiple sites and my procedure seems to be close to the same as they say. I dried the rust in an aluminum container, and noticed a few little holes that were not in there before, might this be the problem?

Your problem may be to course Al, I had simular thing happen to me because of not fine enough Al.

I have tried several types of thermite. The ones that really worked are the classic Fe2O3/Al one and one in which I have used Cr2O3. This I have obtained calcinating ammonium bichromate of which I have a quite large amount (about 20 kilos). Besides forming the beautiful volcano type effect, burning the bichromate created a huge amount of almost pure Cr2O3.
Regarding the effectiveness of Cr2O3 Thermite it is less effective and spectacular than the one using Fe2O3.
For initiating the thermite I used ammonium perchlorate / 1,3 diaminopropane diperchlorate mixture with very good results.
I think Fe2O3 can be obtained from hardware stores. It is used as a pigment for oil paints a.s.o.
Of course it is reccomended you calcinate it in the oven for at least 30 minutes in order to remove all moisture.
As for aluminium powder I also get iti from the hardware store. It is very fine mesh and also used as a silvery pigment. In Romania the price is about $2 per kilo.. so you get plenty of it.
I have several pictures of my experiments using thermite on various objects (including a car wreck). As soon as I scan them I will see the procedure and post them.

I dreamt that I did my first experiment with thermite today. I formed the composition into stars, and coated them in a primer so that a black powder charge would ignite them. I then created a container similar to an aerial shell, and filled it as I would fill such a shell, substituting the pyro stars for my thermite ones. The fuse was lit and I retreated to a safe distance to watch. The shell burst and the thermite stars went all over the place (as intended). However, some of the stars failed to ignite (which can be fixed). And now to my question. Has anyone else tried this kind of device, and if so, what did you think, and how do you think this would perform as a small incendary device.

Did you find any of the meteorites afterward? I think it would be interesting to make meteorites. You would have to have some nickle in the thermite to make them more authentic. If the drops of molten iron were not tumbling then they should be slightly magnetic. Are they?

I did find some of the stars, both burnt and unburnt ones, I think a fair few of them shattered when the burst charge went off, so a bit more experimentation is needed there with regards to the binder. I didnt check to see if the iron was magnetic or not.

I'm curious of the potential dangers that are linked to thermite and if thermite would be alright to start with being as I have not started making anything as of yet.

I've searched the archives and the only thing I found was a potential headache due to the brightness or fumes, posted by DarkAngel. If I've overlooked anything which is very likely(I need sleep!) please inform me of what I missed or where I can find it.

Just dont go towards the light :p Seriously, it does cause discomfort to your eyes if you watch it when you are too close to it. Also make sure that there is nothing in the area where you plan on testing the stuff, as it does spit (quite violently at times).

Oh yeah... I bought some concrete dye the other day (says Oxide on it) but it didnt elaborate on exactly what oxide it was. It is a deep red, almost brown. It seems to work, but was just curious as to what other oxides they use in concrete dyes, and if they are suitable for use in thermite compositions.

Apperently the red oxide is Fe2O3 while the black oxide is Fe3O4.

Hmmmmmz... I picked it up from Bunnings. The brand is Melcann and it came in different shades of Browns/Reds and also black. The one I purchaced was Dark Red.

i am working on something new...
i am trying to make a "plastic thermite".
a thermite which is like playdough...

I thought of mixing it with NC laquer, or vaseline, or some materials used in making plastic
explosives.
Has anyone ever done anything like this?
i don't know if it will work...
would thermite still work if i would add anything like what i mentioned??

Further up the thread it talks all about using plaster of paris for what I believe is referred to as a 'binder'. I think that answers your question.

The idea of castable or plastic thermite has been mentioned several times now and I would like to add a few comments of mine on the subject.

If a pyrotechnic composition of "thermitic kind" is mixed/diluted with any additive, it will soon loose its special properties of forming a hot semi-liquid melt of a metal and an oxide. Additives will lower the temperature of reaction and/or form gasses and flames that will alter the effect into something that will look like a more ordinary pyrotechnic effect. In other words, you will end up with a mixture that is not really thermitic any more!

But, if very low amounts of stearic acid, wax or paraffin is added to a Fe2O3/Al mixture, and the mix is milled REMOTELY for several days, you will end up with a thermite as fast and violent as flash powder! This is probably because of increased gas production as well as an effect of particle size reduction and increased intimacy between the particles.

The following in from the construction process for a product called Hebel block, which is an aerated concrete brick/block:
The raw materials are then automatically weighed and measured in a mixer. To this mixture is added water and aluminium paste. After mixing, the cement slurry is poured into a mould. The aluminium paste reacts with the alkaline elements in the cement and forms hydrogen gas.IIRC plaster of paris is alkaline (I may be wrong here), so how does it react when used for casting thermite, given that thermite contains aluminium?

Good point. The reason why bases usually sensitize aluminium is because they remove the protecting oxide layer from it, thus making it more sensitive to water for instance. However I think CaSO4, which is less alkalic and is used in smaller proportions (and with less water) than Ca(OH)2 in cement, wont be much of a hazard for an aluminium based thermite..

Thats true. But there would still be some formation of gasses from the alkali reacting with the aluminium. Granted it may be small, but it would still be there. Time to find some plaster of paris and do some testing :p

Plaster of Paris is in fact partially hydrated calcium sulphate - CaSO4*1/2 H2O
It isn't alkalic at all, as it is a salt of a strong acid-H2SO4-and a moderate strong base-Ca(OH)2.
I think the reaction is taking place between Al and CaSO4 (I remember that an incendiary mixture is made from Al and Plaster of Paris...look here http://flashbangboom.homestead.com/yields_etc.html - as you can see the added water is not starting a reaction at all...).

The possible reaction that comes to my mind is:

3CaSO4 + 8Al --> 3CaS + 4Al2O3 (it may be only theoretical, I'm not sure about it...).

So Al is taking the oxygen from CaSO4 not from Fe2O3 as in "regular" thermite...This may mean that some other chemicals containing oxygen in a "stable" form could be used in the same manner as CaSO4 in the above described mixture.

Thanks for clearing that up. I shal still do a few test just to see how it affects the mix (burn time etc etc)

Right now I'm in the process of making iron oxide (it isn't going very well).
I got couple pounds of maybe .25 or .5mm diameter steel filings, and my bathroom is currently filled with flat dishes and plates with salty damp steel powder. It is very slowly rusting away; I thought that it would take a couple hours, more like a couple weeks. :mad:
I also have a bunch of it sitting in a ice cream bucket totally covered by salt water, aside from turning the water black, it's done nothing. Would putting a fish tank aerator or keeping it agitated speed up the process noticeably?

Yah, yah, I know, I could buy it for cheap, or precipitate it from the sulfate, but the iron filings are free and the idea of buying rust just seems wierd, usually its an unavoidable and unwanted side effect
If anyone wants to know, the steel was taken from an car dealership, the thing that smooths out brake disks is similar to a lathe, it puts out tons of little steel chips.
Not having experience with thermite, this is just hearsay, but apparently one should be careful of lighting thermite on wet earth, as the moisture in the earth can vapourize, throwing molten iron everywhere, which is bad (unless you get someone else to light it).

I have found that with the iron fillings I get from an auto store which also lathes things is very oily and doesn't rust very well. Whats wrong with buying it? 1kg tub for $10, thats beats the hell out of making it.

Dude, I would just buy some. Its sold as concrete dye. I know it seems funny buying rust, but its worth it if you are interested in thermite. I havent heard about the wet ground thing, but I do know that if you throw water on it while it is burning, it can create a steam explosion.

With regards to my previous post on trying to cast with plaster, I didnt end up trying it. I did however try adding a small amount if KNO3 to the mix, and it made it a lot easier to light (duh).

if you really want some quality iron oxide then go find a pottery supply shop and they sell really high quality powder for dying glazes of something.

As well as the wet ground danger, if you ignite thermite on CONCRETE the water chemically bound by the cement when it hardened will be released by the heat, possibly causing a steam explosion. Shoot your thermite tests on DRY sand, or on dry metal if you're trying to weld/cut/puncture. And use the coarsest grade of Al that you can, fast burning thermites made with pyro grade Al will often blow up. In fact, a thermite type mix of fine black Copper oxide and pyro Al has been used for "flash powder" in aerial salutes.

i found in an old (15 years) book called explosives engineering a text about thermite which says that the best source for iron oxide is the oxide found on iron magnets (the literall translation is maganatic iron oxide) does any one know if this information is true or not ?

the book "Ellern, Herbert - Military and Civilian Pyrotechnics" speak about the thermite:


http://perso.wanadoo.fr/lupyr/pourforum/thermite,ellern.JPG

pics (http://perso.wanadoo.fr/lupyr/pourforum/thermite,ellern.JPG)

According to this reference: http://dictionary.reference.com/search?q=magnetic%20iron, magnetic iron oxide is Fe₃O₄, or what is commonly sold as black iron oxide.

Its really very easy to make large amounts of Fe2O3.
I make it by electrolyzing salt water with a piece of rebar as an anode, this forms a black precipitate. (iron hydroxide Fe(OH)3). When most of the rebar is gone I decant and filter the solution to collect the mushy black hydroxide. I then put the mush in the oven at the highest setting until it all turns to a bright red powder.
2Fe(OH)3 + heat > Fe2O3*3H2O
Fe2O3*3H2O + heat > Fe2O3 + 3H2O

When I use a computer power supply running at 5V 10A, and when I pump air in to the solution with a fishtank pump, (optional) I can make about one cup of thermit a day.(I really cant remember exactly how much, as it has been a long time since I did it last).

Or you could alternativly go to your local hardware store and find a range of oxides in 1kg tubs for around $10 including Fe2O3, Fe3O4 and Cr2O3 :p

Anymore I always use magnetite, or Fe2O4 in my thermite mixtures. It ignites much easier than regular thermite. I seen a diagram where fine thermite ignited a much coarser grade. If I use my regular thermite to ignite a mixture or Fe2O4 and aluminum foil that was ground in a blender, I might be able to produce a big enough reaction to actually penetrate something.

My hardware also sells a bright blue oxide colouring, does anyone have any idea what that might be?

Sounds like your basic anhydrous Copper (II) Sulphate. Is it a light blue? Almost neon? I don't know of an oxide that colour. Can't you just look at the label?

Anydrous copper sulfate isn't blue and copper sulfate is only blue if it contains water.

http://www.google.com.au/search?q=cache:3lxkDxWJlxwJ:www.ancilla.edu/Portfolios/NServis/%2520Gravimetric%2520Analysis%2520of%2520Hydrated% 2520C20opper%2520Sulfate.doc+anhydrous+copper+sulf ate&hl=en&ie=UTF-8%

It might be ultramarine (Sodium disilicate). Very bright blue, no copper involved. Cheap. Nontoxic. Anything used to color concrete would have to be cheap- Copper is expensive, and any copper salt also would kill grass adjacent to the concrete.

xyz, good point, it is only blue when "wet" - my bad. I should remember doing that experiment.

Bert, good point about the cost, but scarletmanuka doesn't mention any application. Sodium Disilicate isn't an oxide, either.

I believe he is talking about coloring agents for concrete. scarletmanuka, is that what they're for?

Cobalt Blue (CoO) was the only blue inorganic oxide dye I could find by a quick search. Apparently it is mostly used for colouring glass and ceramics though..

Yes it is for a colouring dye for concrete. However, even though it says oxide colouring on the label, I think Ultramarine is the best bet, because I bought some and it failed to ignite with flake Al. It is also insoluble in water which rules out Cu(II) salts, not that it is the right colour anyway.

Try mixing a bit with 70% perchlorate or chlorate and 30% of a fuel such as shellac or red gum. If it burns with a Sodium yellow, you pretty much know what it's got to be. It's a good yellow colorant, cheaper than Sodium oxalate and non-hygroscopic.

Thanks Bert, it does indeed impart a yellow flame, but I don't think I will be going through 500gr of it in a hurry. Bit of a let down really, I was hoping it might be something slightly more exciting than ultramarine.

Here is how I got rust really fast!! I did a bit of reading on how to accelerate oxidiation of iron. So I came up with this idea myself: I added 50 grams of steel wool to a 1000ml beaker. I then added 3 grams salt, and 10 grams citric acid. After that I poured 250 ml 27% H2O2 into the beaker. There was immediate foaming due to the wool decomposing the H2O2, and alot of heat generated. Within 15 minutes the faoming almost stopped, so I added another 100 ml H2O2. After about 30 minutes just about all of the steel wool was converted to Iron Oxide (III). Maybe 5 grams was left. Wow, that was fast!! Works excellent!! Also, An excellent source of aluminum to make powder from are heatsinks in electronic equuipment. Especially T.V.'s because they have quite a few pure aluminum heatsinks which are quite large. :D

That seems a bit wasteful of hydrogen peroxide. Then again I don't know how much it costs you. I pay 7 dollars Canadian for a litre of 35% so it's not terrible, but I still feel that electrolysis of iron or even the method of HCl and a metal hydroxide could come out to be more cost efficient method of production.

Well I just had to try it to see how well it works, and I don't mind about cost too much. I get a gallon of 27% H2O2 for about $17. I will most likely go to Lowes and get a tub of Fe2O3 for futher thermite experiments. I can't wait to light this batch off. I am going to try lighting it with a propane torch, but if that doesn't work I will have to go pick up some magnesium. BTW, propane torches in air burn at 1899 degrees celcius. :D

Kid sparklers work wonders for thermite. Get it going right quick without fail. Cheap as shit too.