Sciencemadness Discussion Board

Exotic thermites & analogs

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nitro-genes - 20-11-2006 at 14:29

Wow, that was more violent than expected! :o I suppose the thermite burns a hole through the ice first that acts as a confiment for the rest of the formed steam. With liquid water instead of ice the results wouldn't be like that I guess... :)

Unlike that cheesy and staged British program Brianiac, german TV used to have some really interesting science shows. Especially the "Knoff Hoff show" was a great program...

Axt - 20-11-2006 at 16:59

Quote:
Originally posted by nitro-genes
With liquid water instead of ice the results wouldn't be like that I guess... :)


"A phenomenon of considerable industrial importance in recent years is the vapor explosion, often referred to as a thermal or steam explosion. This phenomenon results from the extremely rapid heat transfer from hot liquid (e.g., molten metal) to cold liquid (e.g., water) when the two are contacted together. Sporadic explosions resulting from this phenomenon have been responsible for loss of life and property in industry for a number of years, and efforts have been made to understand the extreme violence of these interactions. It is not presently known exactly how these explosions are initiated. However, resultant effects of these interactions are dramatic, and substantial amounts of energy are released during such explosions." <a href="http://www.freepatentsonline.com/patents/us/521/5212343/5212343.pdf">US5212343</a>

"A aluminum liner, weighing 2.6 grams, was filed with 11 grams of water and sealed. The liner was placed inside of a well drilled in cold pressed pyrotechnic mix No. 1 CuO pellets. The pellets had been formed by cold pressing 74 grams of the mix No. 1 CuO. The pellets and liner were placed on a retaining stand and secured into place with the igniter plate and threaded rods. A Holex.TM. igniter was used to initiate the reaction of the pyrotechnic pellets. About 0.2 seconds after the initiation, an explosion occurred when the molten products of the pyrotechnic pellets and molten aluminum from the liner contacted the water." <a href="http://www.freepatentsonline.com/patents/us/437/4372213/4372213.pdf">US4372213</a>

[Edited on 21-11-2006 by Axt]

chemoleo - 20-11-2006 at 18:46

This is highly interesting.
I am particularly impressed about the effect of the molten metal/metaloxide onto the ice after the explosion, producing pyrotechnic effects in its own right.

This is something that can be definitly tried, particularly for members from Russia and Canada, or Antarctica, given 60 members are from there :P


I wonder what'd happen if it was done the other way round: a large thermite charge in a slightly larger beaker in water. Or how about methanol/ethanol, or, to get more fancy, things such as ammonium chloride, hydrazine chloride, ammonium persulfate etc? I bet a lot of experimenting could be done there.


[Edited on 21-11-2006 by chemoleo]

DeAdFX - 20-11-2006 at 19:48

Hell while we are at it lets use a frozen block of hydrogen peroxide. I have a feeling the iron oxide would decompose the frozen peroxide causing the thermite mix to fly into the air. The oxygen released from the peroxide and iron oxide would then combine with the Aluminum.

[Edited on 21-11-2006 by DeAdFX]

nitro-genes - 21-11-2006 at 02:30

Ahh, now I understand what is happening...:)

If you drop some water on a hot metal surface it will not flashboil at all since there is an insulating vapour layer layer between metal and water. I forgot that the metal is also a liquid in this case. With two liquids, the vapour layer is not stable and will dispers the liquid metal troughout the water, causing instant flashboiling of the entire water mass...

Replacing the water by some liquid fuel is the next logical step indeed.... :D

I'll look into it, I've plenty of aluminium powder left, I'm a bit short on the iron oxide though... :(

Bert - 29-11-2006 at 00:25

Here's a bit of historical interest-

Aluminum as a Heating and Reducing Agent, by Dr. Hans Goldschmidt and Claude Vautin
http://pyrobin.com/files/thermit(e)%20journal.pdf

(This is from 1898, before Aluminum became a cheap metal)

farmisist - 18-12-2006 at 11:33

The other day I decided to try to use thermite to remove a tree stump. I used probably about 2Kg of thermite (Fe3O2) for this. And against my better judgment I threw in some Teflon power/Al mix. Fortunately there weren’t any repercussions from any Fluorine gas. The experiment as a whole failed, the stump remained largely unchanged, and actually, some bits of paper were left over after the reaction. But if you wanna see a video of it, its here http://video.google.com/videoplay?docid=4864739774767110399&...

(We put a tire rim around the stump and some boards to protect my mom's plants.)

Nixie - 18-12-2006 at 22:00

Why not do as farmers do and drill holes, soak it with nitrate solution, and later add some fuel and light it?

farmisist - 20-12-2006 at 15:56

Well to be perfectly honest I was just looking for a good excuse to use some thermite. Thats what we'll probably end up doing now that the thermite didn't work out. Thanks anyway for the suggestion.

Bert - 20-2-2007 at 08:15

Quote:
Originally posted by farmisist
Well to be perfectly honest I was just looking for a good excuse to use some thermite.

Thermite is good for puncturing or welding metals, but isn't magicaly capable of doing similar things to wood, concrete or even paper. There were a number of WWII era government tests done on document destruction mechanisms for safes, thermite was not effective... Bricks of Sodium nitrate and coarse Magnesium were eventually used, as I recall. And even that wasn't outstandingly effective if there were thick piles of papers. Cellulose is a good insulator!

egloskerry - 2-4-2007 at 22:16

Alright, I have my ingredients.

5lb Al
3lb Zn
1lb CuO
1lb Cu2O
1lb V2O5

How do I find these stoichiometric ratios? It's been a LONG time since I was in a chemistry class, and my next one isn't until fall semester. Really, I've forgotten a hell of a lot.

UnintentionalChaos - 2-4-2007 at 23:01

Even wikipedia can help you there. The oxides are your oxidizers and the two pure metals are fuels. I don't think Cu2O will get you much since it is a lower oxidation state. V2O5 is pretty toxic as well, so be careful with it. The aluminum will do a much better job than the zinc for the reactions. The CuO will go off like flash powder if it is fine enough.....avoid the plume of vaporized copper and alumina and subsequent metal fume fever. Assume that you are going all the way to metal with the oxidizer...so, CuO -> Cu. For every mole (measurable quantity, just use wikipedia or a periodic table) of CuO, you need to use up a mole of oxygen atoms. Aluminum forms the oxide Al2O3, so two moles of aluminum will reduce 3 moles of copper (II) oxide completely. This means that for every mole of CuO, you need to mix in 2/3 of a mol of aluminum. Looking up the numbers, 79.5g of CuO need 18g of aluminum powder added. ~100g of such a violent thermite is probably an invitation for the cops and/or a hospital visit for the first experiment. Scale down to a few grams. The V2O5 would be very nice for making Vanadium metal if you keep an element collection.

Levi - 3-4-2007 at 01:47

Quote:
Originally posted by egloskerry
How do I find these stoichiometric ratios? It's been a LONG time since I was in a chemistry class, and my next one isn't until fall semester. Really, I've forgotten a hell of a lot.


UnintentionalChaos has posted the correct information but I'm going to speak to you like you're mentally challenged for a moment to make sure you understand the theory.

Because stoichiometric ratios are concerned with the proper number of atoms reacting and because lab equipment measures mass rather than atoms, it is inconvenient that all atoms do not weigh the same. Thanks to the periodic table we are able to determine the weight of a set amount of atoms (the mole). 1 mole = 6.022 x 10<sup>23</sup> units, by the way. Anyhow, 1 mole of copper atoms does not have the same mass as 1 mole of aluminum atoms or 1 mole of oxygen atoms. The mass of a mole of a given type of atom is found on the periodic table underneath the symbol.
Copper has a molar mass of 63.54 grams per mole.
Oxygen has a molar mass of 16 grams per mole.
Aluminum has a molar mass of 26.98 grams per mole.

To determine the amount you need of each, start with a balanced equation.

3CuO + 2Al --> Al<sub>2</sub>O<sub>3</sub> + 3Cu

Simply, 3 molecules of CuO react with 2 molecules of Al to form one molecule of Al<sub>2</sub>O<sub>3</sub> and 3 molecules of Cu. Therefore, 3 moles of CuO react with 2 moles of Al to form one mole of Al<sub>2</sub>O<sub>3</sub> and 3 moles of Cu. Great! Or at least it would be great if you had a scale to measure the number of atoms in a pile of CuO. Fear not, you likely possess a scale that can measure mass so we can figure out the proper ratios with a little bit of math.

One mole of CuO weighs the same as one mole of Cu + one mole of O. Three moles of CuO, then, weighs 3 * (63.54 + 16) = 238.62 grams.
Two moles of Al weighs 2 * 26.98 = 53.96 grams.
The ratio then is 238.62 grams of CuO for every 53.96 grams of Al.
This is roughly 9:2 by weight.

Levi - 3-4-2007 at 02:10

Quote:
Originally posted by DeAdFX
Hell while we are at it lets use a frozen block of hydrogen peroxide. I have a feeling the iron oxide would decompose the frozen peroxide causing the thermite mix to fly into the air. The oxygen released from the peroxide and iron oxide would then combine with the Aluminum.

[Edited on 21-11-2006 by DeAdFX]


It might almost be worth the cost of the reagents to see a Ag<sub>2</sub>O and Al thermite dripping molten silver into a beaker of concentrated peroxide :D

The silver thermite reaction alone would be almost twice as exothermic as the Fe<sub>2</sub>O<sub>3</sub> variety and I expect silver would do a much better job of decomposing the peroxide than iron would.

[Edited on 3-4-2007 by Levi]

egloskerry - 3-4-2007 at 11:34

I imagine silver oxide will be fairly hard to get. Expensive, too. That V2O5 was 13$.

The scale is forthcoming. I'm still pricing them.

DeAdFX - 3-4-2007 at 11:43

There are some sellers of AgNO3 and Ag2O on ebay.. Their prices are quite nice in comparison to the other resellers of overly priced transition metal chemicals.

egloskerry - 3-4-2007 at 11:59

Can't seem to find any.

I am getting my camera this week, so I'll be sure to videotape all these reactions.

mrjeffy321 - 4-4-2007 at 21:22

Quote:
Originally posted by UnintentionalChaos
I don't think Cu2O will get you much since it is a lower oxidation state.

Actually, Cu2O does give off a very decent thermite reaction.
Cu2O thermite is not as 'vigorous' as CuO thermite (CuO thermite can be VERY reactive), but it still is very much comparable to Iron Oxide thermites in terms of the reaction it produces (from my experience).

In doing a Cu2O thermite reaction, I was left with a very nice lump of pure Cu metal in the end.
Performing the same reaction with CuO would leave me with virtually nothing in the reaction vessel since all the products were vaporized / thrown out during the reaction.

egloskerry - 5-4-2007 at 12:58

I'm guessing I use Mg ribbon to light these different compositions? I got a good deal on 75ft of it for just this purpose. It works well for Fe thermite but I want to make sure it'll work with this, too.

According to wikipedia, silver oxide decomposes when exposed to light.

Alright, I worked everything out. I scaled them all down to be about 50g total. Everything is rounded to a tenth of a gram.

3CuO + 2Al -> Al2O3 + 3Cu
3Cu2O + 2Al -> Al2O3 + 6Cu
3V2O5 + 10Al -> 5AlO3 + 6V
CuO + Zn -> ZnO + Cu
Cu2O + Zn -> ZnO + 2Cu
V2O5 + 5Zn -> 5ZnO + 2V

3CuO + 2Al -> 39.8 + 9
3Cu2O + 2Al -> 42.9 + 9
3V2O5 + 10Al -> 34.1 + 16.9
CuO + Zn -> 26.5 + 9
Cu2O + Zn -> 35.8 + 6.8
V2O5 + 5Zn -> 18.2 + 32.7

[Edited on 6-4-2007 by egloskerry]

Levi - 6-4-2007 at 02:44

How easily ignitable the mix is depends heavily on particle size. If the particle size is the same for all mixes then I expect any method capable of initiating iron thermite will also initiate the more exotic blends but I'm only guessing here. V<sub>2</sub>O<sub>5</sub> is beyond me but if any of the afore mentioned is doomed to failure I imagine it is the vanadium / zinc mix but this is just a hunch because I couldn't find any thermodynamic data for V<sub>2</sub>O<sub>5</sub> although one site did say that vanadium metal is usually produced by reducing the pentoxide with calcium--of course calcium is considerably more reactive than zinc. Particle size and proper ratio will be key.

egloskerry - 6-4-2007 at 08:39

The Al is somewhere around 600 mesh, the Zn is 300. I'm not sure about the others because I don't have them yet. I believe they were shipped on monday, so I should have them soon. They're in massachusetts.

[Edited on 6-4-2007 by egloskerry]

Commercial Niobium Metal & its alloys

Aqua_Fortis_100% - 7-4-2007 at 09:00

Some months ago, my school did a excursion with some students (including i :D) to another city where stay 2 big firms of minning industry. one of phosphate prodution for fertilizers, and another of niobium prodution.
the second , has the BIGGEST niobium mine and prodution in the world. (english version: http://www.us.cbmm.com.br/ ) and can produce (estimated) very easily bulk quantities of niobium metal for at least 300 years!
first we go to mines (all at soil surface, neither at subsoil), and after to prodution (metallurgical) plants( http://www.us.cbmm.com.br/english/sources/mine/operat/f_oper... see "Standard Grade Ferroniobium Production" ) and to a big lab of researches of niobium uses and anothers things.
i'm still quite wondered with the live vision of the big eletric arc furnace of Nb/Fe alloy production . my colleague take in this moment some photos..
below, the photos:

(note the aluminium sparks going out of the molten Ni-Fe : .. one of the most beautiful things )

[Editado em 12-4-2007 por Aqua_Fortis_100%]

fotos 024.jpg - 88kB

Aqua_Fortis_100% - 7-4-2007 at 09:25

This photo below is after the molten alloy go out of the furnace and stay on metal suports on a small "rail" for transport to another place of the plant.

in the conferences room of the firm (CBMM), a metallurgical engineer and a mine engineer are in this , explainning to the students all of the mine and processes.. the metallurgical eng. explained which the Al powder (unfortunately he not said the mesh grade) are mixed with Nb2O5 and the desired amount of iron (though he not said if this iron is in the form of Fe or Fe2O3) and initiated and keep by eletric arc, and then the molten alloy is collected below the furnace. i asked about details, and he says which there are another methods for small scale and researche and others furnaces for producing anothers alloys.
the CBMM also, sell the niobium oxide for other purposes.
my school planning to do another excursion with others teams of students, after holidays, and i think in will ask my teacher to see if she can get small amounts of Nb2O5 just for "souvenir" ehehe, because its very probably which not sell small amounts, only big.
if i get this i will try make a different thermit.. i know which this thermite not auto sustain it self, so i can add small amounts of Fe2O3 to see the progress.. what about this?


[Editado em 12-4-2007 por Aqua_Fortis_100%]

fotos 026.jpg - 110kB

12AX7 - 7-4-2007 at 10:59

Mind uploading those pictures to an internet server, mmm?

Tim

Aqua_Fortis_100% - 11-4-2007 at 20:00

how, finally ,i think, i turn able to upload this photos..was quite difficult to me editing these photos ,since original size was MUCH larger to put here without irritating members..

12AX7 , thanks to advise me.

i really like to try this if my teacher will got a sample to my..
anyone has made mad experiments with Nb2O5?

edit: ( i remember that when in the lab i asked (with description) to the firm chemist why i cann't use some Nb2O5 in experiments as catalyst in the production of SO3 instead of V2O5, then he said anything as the resistance of heat(necessary in the catalysis) which the Nb2O5 offer without decreasing in performance without decreasing greatly in performance, compared to V2O5. Proceed this information?
i hate myself by not ask to he some sample of Nb2O5 (of course!) and more detailed info about thheir reaction with aluminium , chemistry and their metallurgy.

[Editado em 12-4-2007 por Aqua_Fortis_100%]

Nixie - 11-4-2007 at 20:08

WTF? The reply notification email I'm getting is entitled thus:
"Nova resposta a � Subscrito Exotic thermites & analogs"

Aqua_Fortis_100% - 11-4-2007 at 20:21

Quote:
"Nova resposta a � Subscrito Exotic thermites & analogs"

something as "new reply to Exotic thermites & analogs thread"
really i dont know why this appeared in your email notification..i think should be my profile edited in portuguese.. so i NOW change to english to not getting more troubles..
really sorry by anything.

[Edited on 12-4-2007 by Aqua_Fortis_100%]

12AX7 - 11-4-2007 at 21:01

Ahh, I love fire...

If they're doing iron AND niobium, it must be a ferro- master alloy for alloying (in this case, to make high strength alloy steels). See also: ferrotitanium, ferrosilicon, etc.

I'm betting the product is quite brittle. Most master alloys are. Do you know if they make purer grades of the stuff?

Tim

Aqua_Fortis_100% - 11-4-2007 at 21:52

Quote:
originally posted by 12AX7
I'm betting the product is quite brittle. Most master alloys are. Do you know if they make purer grades of the stuff?

Yes. all products and alloys to research and for sell.(and all kinds and strength. high purity)
(one of their labs where the researches are done only to study new uses of niobium in differents uses and purposes, as in rocket engines, this Master alloys, others alloys to catalysts, use in traces (or more) amounts in "common" metals, etc.. and also several niobium compounds, as the Nb2O5..but this is much less important to they.. alloys = $$$$ :cool: )


when still in the metallurgical plant i got a solidified small "cake" (actually a melted metal) but unfortunatelly i'm not totally sure that's is Nb-Fe or contains Nb.. thanks for said about brittle aspect. i will try tomorrow hit with a hammer to see the easily in break up

edit 2: sacrificing a "souvenir": all sacrifices to benefit (my)chemistry knowledge..
[Edited on 12-4-2007 by Aqua_Fortis_100%]

[Edited on 12-4-2007 by Aqua_Fortis_100%]

Aqua_Fortis_100% - 12-4-2007 at 19:36

Quote:
originally posted by 12AX7 :
I'm betting the product is quite brittle. Most master alloys are. Do you know if they make purer grades of the stuff?


You are right again!!!

the melted metal "souvenir" was quite and surprising breaked up easily with the hammer..only moderated hits and small pieces was obtained..
therefore with your explanation, i'm now quite sure that the pieces i've are a sample of NbFe..
so i can start with a new collection: elements and metals as suggested before by anyone...

egloskerry - 19-4-2007 at 12:12

Well, I tried Cu2O and Al, no reaction. I mixed 42.9g Cu2O and 9g Al and used a bit of that, and used Mg ribbon as an igniter. Any ideas?

12AX7 - 19-4-2007 at 12:33

Well, it worked for me. I used magnalium, which does ignite better. Try heating it to 1200C maybe?

Tim

egloskerry - 19-4-2007 at 18:34

Mg burns at above 2000C though.

12AX7 - 19-4-2007 at 20:13

But it doesn't necessarily heat enough of the powder to that temperature.

People using ribbon seem to have the opinion that the stuff is hell-ass thin. I've never had any.

Tim

mrjeffy321 - 19-4-2007 at 20:28

I am not sure if it has to do with the nature of the Cu2O thermite or if it is just a coincidence, but I could not light it using Magnesium Ribbon either when I tried it.
However, I was successful in igniting the Cu2O thermite with Potassium Permanganate and Glycerin.

egloskerry - 19-4-2007 at 20:53

I have pounds of that stuff. I'll go try that, though I don't have much of the mix I made left.

The Mg ribbon is pretty thin, but it burns slowly. If KMnO4 doesn't work, I'll try a propane torch.

Update: It worked! Twice! Very energetic. I can't wait to see the CuO. Thanks for the advice!

Another update: I just tried Fe2O3 and Zn. Mg ribbon did nothing, but when I tried KMnO4, I could see it wanting to react with very small sparks occuring, and it glowed for about a minute, but eventually it just died out. Is Zn not reactive enough?

V2O5 and Al work, though. However, it's not as reactive as CuO. I'd say it's equal to Cu2O. Got some pure vanadium metal, though. I'd like to know, why did you guys believe V2O5 would be one of the most reactive? I'm a bit disappointed, since that stuff was fairly expensive!

[Edited on 21-4-2007 by egloskerry]

egloskerry - 22-4-2007 at 14:19

Somewhere in this thread, it was said that to get a thermite reaction, the compound must have a greater enthalpy of formation than Al. Is this referring to the oxide or the resulting metal? I'm asking since I'm looking at buying a few more oxides to test:

Sb2O3, CoO, MnO2, TiO2, and ZnO.

mrjeffy321 - 22-4-2007 at 14:43

Any pure element in its elemental form has a standard enthalpy of formation of zero (kJ/mol).
Aluminum metal or any other pure metal under standard conditions has an enthalpy of formation of 0 kJ/mol.
The oxides on the other hand will have negative enthalpies of reactions since the oxidization process is exothermic.

The determining factor as to whether a thermite reaction (or any other reaction) will be spontaneous once ignited is the change in the Gibbs free energy of the reaction. If the change in the Gibbs free energy is negative, the reaction is spontaneous.
ΔG = ΔH – T * ΔS
Where ΔG is the change in the Gibbs free energy, ΔH is the change in enthalpy, T is the temperature of the reaction, and ΔS are the change in entropy.
ΔS values are typically small compared to ΔH values and if a reaction is exothermic (ΔH < 0), this will overpower a ΔS < 0 a lot of times, but not always. Reactions can be spontaneous even if ΔH > 0 since the T * ΔS term might still over power it and make ΔG < 0.
So in other words, in order to know for sure if a reaction will be spontaneous at a given temperature, calculate its ΔG value, not just the ΔH.

Levi - 23-4-2007 at 01:06

You are quite correct, mrjeffy, but lest anyone be deceived I feel it necessary to point out that a spontaneous reaction need not proceed with any haste. A spontaneous reaction proceeding at 1 mol / year would make a pretty lousy thermite (unless you're the type that happens to like watching grass growing or paint drying).

egloskerry - 23-4-2007 at 02:35

I think I may need to wait until I take that chem class next semester, since I don't even know how to calculate any of those initial values.

Levi - 23-4-2007 at 03:00

Quote:
Originally posted by egloskerry
I think I may need to wait until I take that chem class next semester, since I don't even know how to calculate any of those initial values.


They have been determined experimentally. You can find tables for them online or in a chemistry book appendix.

-cyan- - 23-4-2007 at 06:48

hi,
what would u say about P4O10 + Al ? would it work?

12AX7 - 23-4-2007 at 07:12

Doesn't P4O10 sublimate before Al ignites?

HPO4 could do it, with some hydrogen though.

Tim

Zinc - 23-4-2007 at 07:45

Perhaps you could ignite the mixture of P4O10 and Al if you use a very hot burning ignition mixture so that the reaction between Al and P4O10 starts before the P4O10 sublimes away.

-cyan- - 23-4-2007 at 08:05

maybe i could use black powder to ignite it?do u think it works?

Zinc - 23-4-2007 at 08:12

I would use something slower and hotter burning. Perhaps am mixture of Al powder and S. I have heard that this mixture is hot enough to light termite. I have tried to make this mixture from Al extracted from paint and it burns slow but I have never tried to light termite with it. Or a mixture of KNO3 and sugar but I dont know if it burns hot enough. Also you culd use regular thermite to ignite the miture of P4O10 and Al. Perhaps even black powder can be used.

12AX7 - 23-4-2007 at 08:48

Coarse magnalium or magnesium mixed with a pyrotechnic powder (such as KClO3, charcoal and powdered metal) works for me.

Tim

egloskerry - 23-4-2007 at 22:41

Is it possible to get that thermite datasheet that was posted pages back? It'd be very useful.

Also, will Sb2O3 work, since it's a metalloid? Would it even be considered thermite?

[Edited on 27-4-2007 by egloskerry]

egloskerry - 27-4-2007 at 12:48

Apparently the Iron Oxide I have isn't Fe3O4, but FeO. Interestingly, it still reacted very well even when used in the ratios required for Fe3O4, even though it's 3/2 for FeO/Al and 3/8 for Fe3O4/Al, and the molar mass of Fe3O4 is more than three times that of FeO.

12AX7 - 27-4-2007 at 19:47

I think you should run the numbers BY WEIGHT on those chemicals. You've been trapped in school too long. You've forgotten that moles are a waste of time!

FeO is very unlikely as it disproportionates to Fe and Fe3O4 at something like 500-800C (see Brauer).

Tim

egloskerry - 27-4-2007 at 20:01

On the site I got them from, it lists two oxides, red and black. It says the black is FeO.

However, I did get two pounds of each, and I got less black oxide than red. Since FeO has a much lower mol. weight than Fe2O3, two pounds of it should've occupied MUCH more space. So I'm guessing it is Fe3O4 after all.

Are both of them (FeO and Fe3O4) paramagnetic?

[Edited on 27-4-2007 by egloskerry]

mrjeffy321 - 27-4-2007 at 20:55

You cannot always associate a higher molar weight to a higher density (Compare the molar masses and densities of Radon to Lithium).
FeO: 5.7 g/cm^3
Fe3O4: 5.18 g/cm^3
Fe2O3: 5.24 g/cm^3
They are all relatively close to each other in terms of density.

You could do a RedOx titration of with the Iron Oxide (dissolve it in solution with H2SO4 then titrate with KMnO4 to oxidize all Fe+2 to Fe+3, compare experimental results with what would be predicted for the given oxide).

egloskerry - 28-4-2007 at 06:42

Eh, it's not that important. I'll just ask them the next time I order.

But about my earlier post. Would Sb2O3 work, or be considered a thermite? And is it possible to get that thermite datasheet?

12AX7 - 28-4-2007 at 08:19

Sb is reasonably metallic, it would probably work. Sb2O5 would be even better.

Tim

egloskerry - 1-5-2007 at 21:00

I tried 25g each of Cu2O/Al and Fe3O4/Al thermite, figured I'd get some sort of alloy. All I got was a black spot on the piece of concrete. It did, however, burn faster than iron thermite, but slower than copper thermite. I wonder if a ferrovanadium alloy could be made this way.

JAPS - 6-5-2007 at 08:41

Hi all, Al and Fe oxide is still the best method.

I use thermite to demonstrate exactly what thermite is capable of burning through, glass, metal etc.
I use either Al / Fe2O3 or Al / FeO(OH) in the weight ratio 1 / 3. The mixture is placed in a 15 to 20cm. diameter flower pot with a piece of thin cardboard over the hole in the bottom.

The pot is placed on an iron support which is about 10cm. over the material to be burnt through. This means that the molten iron flows through the hole in the bottom of the flower pot and directly onto the glass or whatever is under the pot. The material to be burned through is supported by 4 bricks, and under the material is sand.

You don't need fine Al powder for the main bulk, you can use Al pellets ( griess ) or the cuttings from sawing, anything between 1mm. and 2mm. will work fine.

The thermite is packed into the pot until the level is about 3cm. below the rim of the pot. Now you need a cylinder of paper 3cm. long and 3cm. diameter. The paper cylinder is placed in the middle of the pot and the rest of the thermite is filled around the cylinder.

What you now have is a flower pot filled with thermite except for a hole in the center.

I don't use magnesium ribbon to ignite the thermite because it doesn't always work !!

You now need a mixture of Al powder and Fe2O3 ratio 1 / 3. and 7 storm matches.

Using a rubber band connect 6 of the storm matches together about halfway up the wood, and push the other storm match down between the heads of the other matches until the lower part of the head is below the top of the other matches. Place the " Fuse " into the middle of the hole and fill up with the fine powder. You should see the top of the 6 matches and the seventh single match sticking up in the middle.

After lighting the top match you have about 3 seconds to get well clear !!!

Always have a bucket of water and a fire extinguisher nearby.

Note: The flower pot is clay not plastic !
FeO(OH) is rust and is red-brown
All ratios are weight
Griess is small round parts of recycled Aluminum scrap.
Light well away from anything that can catch fire.

egloskerry - 6-5-2007 at 20:12

Fe2O3 is known as rust. FeO(OH) is yellow iron oxide.

Your ignition process seems very complicated. You should look at some of the other methods that have been posted.

And I feel I have to tell you, it is EXTREMELY DANGEROUS to throw water on a thermite reaction. The temperatures are capable of flash boiling the water and potentially causing a small explosion. Also, water won't put it out, since the metal oxide supplies the oxygen. A fire extinguisher won't work either for the same reason. The only way I could imagine would reliably stop the reaction is to scatter the reactants so they are no longer in a confined area.

UnintentionalChaos - 6-5-2007 at 20:56

Not only flash boiling, but the molten metal is quite capable of stripping oxygen from the water and making a cloud of hydrogen which then explodes/combusts with environmental oxygen

12AX7 - 6-5-2007 at 21:25

I suspect he meant water for cooling things not reacting or intensely hot. Obviously dumping water on thermite is not going to go well.

Incidentially, why allow hydrated iron oxide? Doesn't that make a lot of gas? I've had Fe(OH)3 explode when I've slowly heated mixtures containing it! I would only ever burn calcined rust (which has a dark red-brown color, with almost a purple tinge to it).

Tim

egloskerry - 7-5-2007 at 23:49

And also, Fe3O4 is going to work MUCH BETTER than Fe2O3. In my experience with Fe2O3, a sustained reaction is difficult.

Zinc - 8-5-2007 at 11:24

I also had problems with Fe2O3 but when I used finer Al powder it worked. It burned very fast and the iron was scattered around so I belive that it couldnt melt through a metal plate. It should burn slower.

egloskerry - 8-5-2007 at 17:25

What mesh is your Al? Mine is 625.

Zinc - 9-5-2007 at 03:05

I don't know. It is a silver powder and it floats in air. It is reagent grade. I got it from school.

JAPS - 9-5-2007 at 11:00

Sorry about any misunderstandings !

Rules and regulations require that a fire extinguisher and a bucket of water are on site when I make the demonstration ( makes sense ). It would be classed as an attempted suicide if I were to empty the bucket of water over 2 or 3 kilos of burning thermite ( probably worse than pouring water over burning fat in the frying pan ). Accidents can happen, and sometimes the thermite tends to spit out unexpectedly. Molten iron on someones clothes would not be very nice, so the water is not a bad idea !!

The FeO(OH) burns louder than the Fe2O3, probably due to the attached water crystals, I would also say it tends to burn slower.

I would hazard a guess and say if you were to ignite a 3 kilo mixture of thermite using fine Al powder ( < 50µ ) and Fe2O3 you would get an enormous flame ( maybe an explosion ) and molten iron spread around in a 15 meter radius. Nice to watch ( in the middle of a corn field ) but that 's not the object of the exercise.

The main bulk of the thermite must be Al around the 1mm to 2mm size, this reduces the speed of the reaction and results in the molten iron pouring out of the hole in the bottom of the pot.

The ignition method that I described is what I use when I'm testing. When viewers are present I start it electric from 20 meters. For both methods I still use the primary of powdered Al and Fe2O3. This may appear complicated, but it hasn't failed yet !!

JAPS - 12-5-2007 at 06:46

Hi Zink.

If the powder that you have is what I think it is, then your bright and shiny ( air float ) Al powder is used in the paint industry. If you get it on your fingers then your fingers become a shiny silver color.

It is anywhere between 75µ and 1µ and was made from Al foil. The foil was first cut into small pieces and then milled with some stearic acid to polish it.

The powder is usually mixed with linseed oil ( or similar ) so that it can be applied to canvas.

It's also quite expensive !!

Use a fine dust mask when handling it !!

[Edited on 12-5-2007 by JAPS]

JAPS - 12-5-2007 at 07:35

Hallo 12AX7,

Absolutely correct. The FeO(OH).xH2O is heated up slowly to 230°C for 2 hours. ( Just for interest ) The cooking pot is covered and fixed with a cloth in case of ( volcanic eruptions ). There are usually about 4 kilos in the pot. The starting color is brown-black and ends up at red-brown.

Pyridinium - 29-5-2007 at 16:08

Quote:
Originally posted by egloskerry
And also, Fe3O4 is going to work MUCH BETTER than Fe2O3. In my experience with Fe2O3, a sustained reaction is difficult.


It's been years since I've done the thermite reaction, but I used to use rust (a mixture of Fe2O3 , FeO(OH) etc, exact composition depending on what and how it rusted). I managed to get repeatable meltings of steel can lids, etc.

Come to think of it, my whole batch of rust had been obtained from the outside of a rusted, 55-gallon steel burn barrel. I am guessing the frequent use of the burn barrel drove out quite a bit of the moisture from the rust. It had a deep red-brown color, rather than a muddy ochre color.

I think the ignition method of JAPS sounds pretty good.

I used to ignite my Fe2O3 / Al thermite with a KNO3 / S / C igniting mixture, basically a variant of "green mix". I recall the trick was to get an orange-hot molten globule of burning nitrate-sulfur mixture that would concentrate the heat. It worked, even when the Al wasn't that fine.

Microtek - 31-5-2007 at 23:06

I've found that if you want to make a relatively large charge of thermite, and you don't have access to large amounts of Al-powder, you can do as follows:
Un-roll a length of Al-foil corresponding to 1 part by weight. Measure out 1 part by weight of Fe2O3 and sprinkle it on the foil. Roll up the foil to form a long cord with a Fe2O3 center and load this cord into a container and ignite with regular thermite. It works quite well and is a very cheap way of making thermite charges.

12AX7 - 1-6-2007 at 14:53

Some day I'm going to have to take a few shovelfuls of aluminum cutoffs and swarf and mix with as much iron oxide (probably mill scale) as needed. Then ignite with a few pounds of maybe 20 mesh (aluminum filings), then ignite that with ground thermite (Fe2O3 powder and ground magnalium +100 mesh is what I usually cook up). And ignite that with, say, magnalium (10 mesh, and some 100 mesh), charcoal and KClO3 (makes a sparkler from hell!) and a fuse.

Tim

unionised - 4-6-2007 at 09:54

A strange thought occured to me and I think this might be as good a place to ask as anywhere (my apologies if it's been asked elsewhere; the search didn't find it).
Can you get a mixture of powdered aluminium and ammonium chloride to "fire" like a thermite?
I think the reaction to give H2, N2 and AlCl3 should be exothermic but I don't have the oportunity to try it (my neighbours would call the police). If it does work then it will produce a lot of gas so it might be more "explosive" than a lot of conventional thermites.

h0lx - 5-6-2007 at 01:51

12AX7, make sure you put it in a flower pot and let the Fe drip onto something or in a mould.

unionised - 7-6-2007 at 09:55

That'd be a big flower pot.

12AX7 - 7-6-2007 at 14:33

Yeah, probably loose sand fill and an anvil mold or something.

Would need testing to see if I can get any even slightly controlled composition...be a shame to burn 200 pounds of thermite only to have it crack from gobs of sulfur and carbide or oxide in the metal!

Tim

chemoleo - 7-6-2007 at 16:40

Unionised... I think it would simply be a reaction of HCl and Al, right? when you heat up the NH4Cl, it will decompose to HCl and NH3, at least at the normal thermite igniton temps - and the HCl will react with the Al, presumably. The H2 generated might burn in the air, together with the ammonia, if high temps are maintained. Perhaps a neat way of making anhyd AlCl3, when doing this in an evacuated container? Somehow I doubt though the reaction of HCl gas and Al powder is vigorous enough to be selfsustaining (while decomposing more and more NH4Cl).

12AX7 - 7-6-2007 at 18:02

NH4Cl is a common reagent to make chlorides, isn't it? Al(OH)3 + 3 NH4Cl --> 3 NH3 + AlCl3 + 3 H2O would be the reaction (using reactive alumina hydrate, since alumina is so refractory), although it seems odd that so much water would escape voluntarily from aluminum chloride.

Oh yeah, that's right- an NH3.AlCl3 adduct forms, dunnit? Lewis acid, lewis base, lewis salt as it were!

Tim

Mardec - 19-9-2007 at 06:36

xD

:mad:

I hate when something doesn't work...

I made TH-3 thermite today, the same shit the military uses. I lit perfectly like it should. Burned very intense. Left a big pile of molten metal (Iron probably).

But it didn't get through a small (emty) gas container for my bunsen burner.. The iron stayed on top...

I don't get it, why didn't it go through it? Everything in the facinaty was charred.

I used this comp:

-12 g Fe2O3
-4 g Al
-6 g Ba(NO3)2
-0,2 g sulpher.

I lit it with 50/50 kno3/mg and the whole charge was packed in a 1,5 cm ID carbboard tube with the burning side directly aimed against the bottom of the gas container.

And it didn't even made a small hole.

The container was emty yes, I am not a noob/stupid.

It was one like this: http://content.answers.com/main/content/wp/en-commons/thumb/...

What are these things?! there was an aluminum can holding the tube in place, that completly vanished.

[Edited on 19-9-2007 by Mardec]

12AX7 - 19-9-2007 at 13:34

Try using more. Like, 10 times more.

Tim

Mumbles - 19-9-2007 at 20:53

I've always found thermite to rarely live up to the legend of burning through engine blocks and all that. Even relatively thin steel just gets a slight indent and a big pile of molten iron. About the best I've done is cracked a cast iron frying skillet. That took about 300 or so grams. That wasn't the most ideal thermite though. It was a demo in my chemsitry class. It was the thermite that is sold as by Fischer Scientific.

The_Davster - 19-9-2007 at 21:19

Thermite does not live up to its legend. I once did a test comparing standard stoichiometric thermite to 60/40 CaSO4/Al
10 g of each on identical pickle jar lids(thin steel). The thermite burnt the paint, wheras the cast CaSO4/Al melted a one inch diameter hole. Mind you, the thermite was with very fine oxide and aluminum, so it burnt very fast, and left minimal slag, I never actually got molten iron.

Mardec - 20-9-2007 at 00:32

Hmm, I thought it would be something like this.

But I am not a very rich pyro so I always try to get maximum bang for the buck. That is why I use small amounts.

CaSO4 sounds interesting.

Btw, I read Fe3O4 thermite is 4 times more potent than Fe2O3 (wich I used). Is this true?.. That would explain the crappy results from Fe2O3. And how Would FeO do?

And what is the most powerfull thermite mixture without very exotic oxides?

Btw, my aluminium was 250 mesh atomised, is this to thick?!

12AX7 - 20-9-2007 at 01:16

Fe3O4 contains a few percent less oxygen than Fe2O3, and has slightly higher binding energy. That it is ANY bit more powerful is bull, and that it's four times as power is bull shit.

Is CuO an exotic oxide? CuO + Al (approx. 3:1 by weight, IIRC) burns like flash powder and is shock sensitive.

Tim

woelen - 20-9-2007 at 04:35

MnO2 + Al also makes a very fast thermite, which is relatively easy to ignite. Obtaining MnO2 is easy. You can buy it at pottery/ceramics stores.

Mardec - 20-9-2007 at 09:17

Quote:
Originally posted by 12AX7
Fe3O4 contains a few percent less oxygen than Fe2O3, and has slightly higher binding energy. That it is ANY bit more powerful is bull, and that it's four times as power is bull shit.

Is CuO an exotic oxide? CuO + Al (approx. 3:1 by weight, IIRC) burns like flash powder and is shock sensitive.

Tim


CuO isn't exotic, it is expensive.. But I do have some, but I can't seem to light the thermite with CuO (homemade)

Is 250 mesh to thick?!

I couldn't light the normal thermite either, but the TH-3 comp did light.

Maybe I should get better Al.


And omg http://en.wikipedia.org/wiki/Thermite The guy who wrote this is so stupid, and I believed it at first look.. Yeah the Fe3O4 lookst stronger in the equation. Only the reaction is with 4 times more Al then the Fe2O3 one. Fe2O3 thermite is stronger indeed... nice

I think about ordering 400 mesh uncoated Al for thermite.
Quote:
Originally posted by woelen
MnO2 + Al also makes a very fast thermite, which is relatively easy to ignite. Obtaining MnO2 is easy. You can buy it at pottery/ceramics stores.


Does MnO2 make stong thermite? MnO2 seems to obvious..

[Edited on 20-9-2007 by Mardec]

Nixie - 20-12-2007 at 06:04

Quote:
Originally posted by The_Davster
60/40 CaSO4/Al

Al2(SO4)3/Al works nicely too, and you can make that by adding H2SO4 to Al powder and warming it with a low flame until the first reaction turns it into a foamy concrete-like substance. Then it ignites easily from a propane torch. I made a thread about it a while ago. However, the reaction is extremely quick, like a flash powder--due to the fact that the Al is a powder. I don't have a source for larger mesh Al :/
How did you get anhydrous CaSO4?

[Edited on 20-12-2007 by Nixie]

The_Davster - 20-12-2007 at 12:55

I just used plaster of paris
The exact procedure is on NickF's website:
http://flashbangboom.homestead.com/yields_etc.html

Nixie - 20-12-2007 at 13:05

Quote:
Originally posted by The_Davster
I just used plaster of paris
The exact procedure is on NickF's website:
http://flashbangboom.homestead.com/yields_etc.html

"Bake it in the oven at gas mark 1 for a few hours...then increase the temperature to gas mark 2 or even 3"
Huh? WTF is "gas mark #". Any oven I have, or for that matter have seen, has the temperature specified in degrees Celsius or Fahrenheit. How do I figure correspondence? Would "mark 1" be something like 70*C or more like 110*C or what?

I'm curious how the energy output from using the calcium sulfate compares to using the aluminum sulfate instead.
Preparing the aluminum version is easier and much, much faster (well, assuming you have sulfuric acid, but almost anyone can easily find the drain cleaner version).

[Edit:] Some stuff on that site doesn't make sense. For example:
"11) Allow the Sucrose Nitrate to dry at room temperature. This can be done very quickly if it is softened at 30*C and rolled into a <b>ball</b>, so that it has a <b>low surface area : volume ratio to speed up drying</b>."

LOL wut?!

[Edited on 20-12-2007 by Nixie]

The_Davster - 20-12-2007 at 13:48

I put it in the oven at around 120C for several hours.
I was worried about ignition, but without cause, as a propane torch had no effect on a small piece.

12AX7 - 20-12-2007 at 18:53

Calcium sulfate at 120C? Not much; 3/2 H2O comes off around 200C, and the remaining 1/2 H2O around 600C.'

Sodium sulfate is easier to handle in this regard, and makes an awesome orange flare to boot. :P

Tim

Mardec - 14-1-2008 at 02:29

I am going to try TiO2 thermite. Now I am balancing the equation and I remembered someone saying you will never get pure Ti out of this thermite. Only TiO.

So should I use TiO2 -> TiO or TiO2 -> Ti

mrjeffy321 - 15-1-2008 at 11:23

I do not discount the notion that it is possible to obtain Titanium metal from a thermite reaction, however in my experience it has shown to be difficult to achieve.

In my experience TiO2 + Al, stoichiometrically balanced (assuming Al2O3 and Ti metal products), thermite reactions do not appear to be successful in producing Titanium metal. Instead, what I end up with was a dark / blackish lump of fused material with nothing to indicate the presence of elemental Titanium.

Initially, I thought that this black material must be Titaium(II) Oxide, TiO, and that the Aluminum powder was not successful in reducing the TiO2 all the way to Ti metal but instead stopped half-way. I based this assumption on incomplete / incorrect information concerning what color certain Titanium Oxides should be. Of course, TiO2 is white. But it turns out that TiO is actually golden-yellow colored, so obviously the black stuff could not be TiO. A far more likely candidate for the black product of the TiO2 thermite reaction would be Titanium(III) or Titanium(III, IV) Oxide since these are supposed to be dark-violet and black colored, respectively.

In order to get some experimental evidence to back up this assumption which was based solely on the color of the product of the thermite reaction, I tried to reduce the (what I am assuming to be) black Ti3O5 further with a more reactive metal…Magnesium [ribbon]. By pressing a lit piece of Mg ribbon against a sample of the black material, it appears that I was successful in reducing the oxide further since the area around the burning Mg ribbon turned yellowish-gold…the same color TiO should be.

So if one wanted to obtain Ti metal from a thermite reaction, one will probably need to increase the amount of reducing agent in the mixture since apparently (in my experience) a straight stoichiometric ratio does not quite cut it. Also, one might need to use a more active metal than Aluminum…possibly Magnesium instead for best results.

Mardec - 16-1-2008 at 07:51

Wow that is a really nice reply!. I will try it, I am going to use german dark as reducing agent. I can get it cheaper than 400 mesh aluminum powder so why bother with the coarser stuff.

I will try one stochiometric and one with a excess of aluminum. I will post the results here afterwards.

Anybody for nanoscale thermite reactions?

-jeffB - 16-1-2008 at 10:25

This might belong in a thread to itself, but it certainly qualifies as an "exotic thermite" in my opinion:

http://www.physorg.com/news119702507.html

"Mixing a low-density composite of copper oxide nanorods (fuel) and aluminum nanoparticles (oxidizer) results in a large contact area between the fuel and oxidizer. On the nanoscale, the low density and large contact area of the nanothermite composite can lead to a fast-propagating combustion." In fact, they're talking about combustion waves propagating at 1500 to 2300 m/s, in the Mach 3 range.

I'm very fuzzy on how they propose to deliver and trigger these mixtures for cancer treatment -- it sounds like they're using the shockwave from the reaction not to disrupt cancer cells directly, but to induce cells to take up a chemotherapeutic drug.

Norrys - 16-1-2008 at 13:48

Quote:
Ursprünglich verfasst von -jeffB
Mixing a low-density composite of copper oxide nanorods (fuel) and aluminum nanoparticles (oxidizer) results in a large contact area between the fuel and oxidizer.


Thats strange. Copper oxide cant be the fuel, and aluminum won't oxidise anything. Is this a journalistic failor, or may this whole article be some kind of hoax?

-jeffB - 16-1-2008 at 17:39

Quote:
Originally posted by Norrys
Quote:
Ursprünglich verfasst von -jeffB
Mixing a low-density composite of copper oxide nanorods (fuel) and aluminum nanoparticles (oxidizer) results in a large contact area between the fuel and oxidizer.


Thats strange. Copper oxide cant be the fuel, and aluminum won't oxidise anything. Is this a journalistic failor, or may this whole article be some kind of hoax?


I think it was more likely just an accidental transposition. (It slipped past ME, oops.) Here's a direct link to another pub from this group, with another application of the nanoengineered thermite:

http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=n...

SiO2

Aqua_Fortis_100% - 16-1-2008 at 19:57

None of my SiO2 based thermites worked at all..

As chemoleo did, I tried with homemade very fine SiO2 ppt from a failed silica gel making attempt ..
I tried to mix several ratios , but neither of these did propagates on it's own.. The only way was to mix one part of this thermite with 2 parts of Fe2O3 thermite..

Chemoleo, in your early attempt you have used sulfur/SiO2 or S/Al/SiO2 ??? What the ratios(if you didn't have used the same of the S.C. Wack reference)?

[Edited on 17-1-2008 by Aqua_Fortis_100%]

mrjeffy321 - 17-1-2008 at 06:58

I was able to get a SiO2 thermite reaction going using a mixture of Silicon Dioxide, Aluminum powder, and Sulfur in the ratio of 9 : 10 : 12 by weight respectively.
Afterward, I was left with a larger, porous, blob of elemental Silicon.

I used ordinary “sand” (unknown particle size, but there was nothing particular special about it) as my SiO2 source, 90% garden Sulfur, and ~200 mesh Aluminum powder.

Aqua_Fortis_100% - 17-1-2008 at 12:36

Thank you, mrjeffy321

I will try latter that and post results..

But will sulfur react with al least some of the silicon metal produced (maybe producing some sort of sulfide)? If yes , how to purify it? Maybe simply putting the cake in HCl will be too easy to be truth: probably gives H2S and the Si chloride will decompose in SiO2 which will mess with your final product..

There is a way to go only with sulfur and SiO2, without wasting aluminium , or it's also too easy to be truth?

Thanks

12AX7 - 17-1-2008 at 13:06

There's enough Al to burn the S, obviously. (SiS and SiS2 are known, but not likely, and definetly not as stable as Al2S3.)

Silicon has a metallic appearance, so for lack of words, it might as well be called "metal".

Tim

chemoleo - 17-1-2008 at 18:46

For making silicon element from quartz sand, check this:
https://sciencemadness.org/talk/viewthread.php?tid=2030&...

All the details are there!

Aqua_Fortis_100% - 18-1-2008 at 15:26

Yeah! This works fine!

Moments ago , I tried, but since I still dont have a good scale for measure very small amounts of reagents, I followed this procedure using volume comparations.. This is mainly because which my aluminium (bronzing powder) is very expensive..

I used about 1 teaspoon of each element (slightly less for sulfur) and mixing was very easy because all substances were very fine , specially the bronzing powder and the homemade ppt SiO2.. Then I've put the mix on a iron plate and ignited it even more easily with a match.. The burning is nice , but are far less quick than other thermites I've made before..
Damn , pretty nice reaction!


Tim,
Ouch, please sorry, dont consider what I've said :(
I'm was so accustomed with the term "metal" used in several and most common metallic based thermites with I forgot entirelly which silicium isn't really a metal , even having some metal characteristics , but a "weird" element ..

Chemoleo,
Good link! I didn't see this thread before..

Although , I will probably dont realize that purification procedure said in that thread, because of fluor compounds described , which are hard to come be and some like HF very watched by police and nasty as well..

Next probably will be try with B2O3 based thermite and after play with some elemental Boron ..
:D

[Edited on 18-1-2008 by Aqua_Fortis_100%]
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