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Author: Subject: Exotic thermites & analogs
chemoleo
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[*] posted on 23-7-2004 at 18:31


Axt, I tried to download the two last movies, but connection was refused.
Are u saying no detonating force was detected on the steel plate? I remember doing exactly the same thing, CuO/Al, and it literally obliterated the container (Fe cans). Couldnt find fragments thereof, and this was in the snow, where fragments should be found easily.
Also, I presume you mean 100g, rather than 100 ml.... (sorry I dont want to split hairs, but it's an important difference)

Also, could you please explain what ' with a .25-06 charge' is?
There are a few non-American members here, so your units may not mean much to us :(

[Edited on 24-7-2004 by chemoleo]




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Axt
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[*] posted on 23-7-2004 at 18:41


Its a geocities problem, note that its trying to pull the movies from some "us.share.geocities ... " or whatever, just have to wait it out as geocities has gone to shit lately, whenever it tries to "share" it doesnt.

Correct that no marks at all on the plate, lot harder then a confined can (assuming you put it into it), but looks very pretty. It was 100ml volume.

Im not American! .25-06, .30-06 necked down to .25 calibre. Quite a powerful rifle, not charge :P that be why I said targets.
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IPN
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[*] posted on 23-7-2004 at 22:15


Thanks chemoleo :)

I used Zn as I have no Al powder. I will try to make some today and also a few more tests. V2O5/Zn (or Al if I am able to make some) should be interesting. :)

PS. Does anyone know any video converter what could make AVI/MPEG files from MOV files? I tried Video Workshop but it just gave me errors.
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[*] posted on 24-7-2004 at 01:33


IIRC, adobe premiere can do that.

I might try P2O5/Al "thermite" if I'm feeling lucky...:P




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[*] posted on 24-7-2004 at 03:52


I tried to make some Al powder from Al plates by grinding them with an anglegrinder, but the powder was too coarse and the mixtures made with it didn't burn at all. :(

So I was back to Zn.

First was Pb3O4/Zn. It burned very fast and ignited a second after the fuse had gone out. :o

Before http://koti.mbnet.fi/otto2000/thermites/Pb3O4_Zn_before.JPG
After http://koti.mbnet.fi/otto2000/thermites/Pb3O4_Zn_after.JPG
Movie http://koti.mbnet.fi/otto2000/thermites/Pb3O4_Zn.MOV

Next was V2O5/Zn. Burned without any sound and with a little smoke only.

Before http://koti.mbnet.fi/otto2000/thermites/V2O5_Zn_before.JPG
After http://koti.mbnet.fi/otto2000/thermites/V2O5_Zn_after.JPG
Movie http://koti.mbnet.fi/otto2000/thermites/V2O5_Zn.MOV

Last was Sb4O6/Zn. It performed very similarly to the V2O5/Zn mix.

Before http://koti.mbnet.fi/otto2000/thermites/Sb4O6_Zn_before.JPG
After http://koti.mbnet.fi/otto2000/thermites/Sb4O6_Zn_after.JPG
Movie http://koti.mbnet.fi/otto2000/thermites/Sb4O6_Zn.MOV

I also tested TiO2 with Zn but I couldn't get it to ignite.

So most of the Zn mixtures do work but they burn quite slowly if compared to similar mixes with fine Al or Mg powder. :(

Thanks vulture, I'll try to find that :)
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[*] posted on 24-7-2004 at 07:06
halide-salt thermites


If K2O/Al works, how about
3NaCl + Al --> AlCl3 + 3Na ?
Maybe a reaction between
3SnF4 + 4Al --> 4AlF3 + 3Sn
Halide thermites mitght work better than regular ones. Especially fluorides.




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[*] posted on 24-7-2004 at 10:31


Formation of aluminum oxide is very exothermic, the chloride is not, therefore thermites the yield aluminum chloride are usually not self sustaining as they are endothermic. Your reaction of sodium chloride with aluminum for example is endothermic by about 529 KJ/Mol and therefore would not commence except by constant heating and probably slowly, only driven by the AlCl3 vaporizing off.

The fluorides though are a different story, whereas the chloride only has a heat of formation of -704.2 KJ/Mol, the fluoride has more then double it, with a heat of formation of -1510.4 KJ/Mol so if you find a fluoride to go with it, with a comparatively low heat of formation you might have a good mix, however fluorides usually don't have a low heat of formation. I could not find the heat of formation of stannic fluoride so I couldn't get the numbers to crunch the reaction you mentioned, however silver (I) or (II) fluoride might prove to be quite exothermic, I've heard good things about using PTFE as well. But these are just the numbers talking.




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chemoleo
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[*] posted on 24-7-2004 at 10:49


IPN, I am a little disturbed by your reactions - for one thing, the paper directly bordering the mix didnt even burn! Can't be high temps at all!
Then -the fact you get so little smoke is also due to that - low temps.
A more interesting question though - did you play at all with the reaction products?
in the case of V2O5, you should have very very fine vanadium lying about, because the melting point of V is surely higher than the temperature of hte reaction. ZnO is probably dissolved by acetic acid, while the Vanadium isnt , so that should leave you with fine V!
Potentially the same goes for some of the others.
Regarding the TiO2 oxide, it didnt work presumbly the oxidation enthalpy of TiO2 is greater than that of ZnO.
Al from the angle grinder - hmm - I tried this once too, but because it gets so hot it has a massive oxide layer. If you really cant find Al (which would be surprising because you have V2O5 etc), you can always make it in a blender with oil and such.

How did you ignite the mixes? Were they all stoichiometric (I am asking becuase of the colour being much grey-er than I am used to with my Al thermites)
I.e. the V2O5 is a beautiful orange normally...




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[*] posted on 24-7-2004 at 10:58


I noticed the paper too. I was also wondering why there wasnt any molten metal. It just kinda looks like a pile of hot powder. KMnO4 + glycerin looks like it burns hotter than the Sb4O6 and V2O5 :o

[Edit]: Isnt the CuO/Zn supposed to be quite violent?

[Edited on 24-7-2004 by Saerynide]




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[*] posted on 24-7-2004 at 13:22


I used the following amount of chemicals.

Zn + CuO -> Cu + ZnO
6.5g Zn to 8g CuO

3Zn + Fe2O3 -> 2Fe + 3ZnO
20g Zn to 16g Fe2O3

2Zn + MnO2 -> 2ZnO + Mn
13g Zn to 8.5g MnO2

4Zn + Pb3O4 -> 3Pb + 4ZnO
4g Zn to 10g Pb3O4

6Zn + Sb4O6 -> 4Sb + 6ZnO
10g Zn to 15g Sb4O6

5Zn + V2O5 -> 2V + 5ZnO
14g Zn to 8g V2O5

I also noted that the temperatures were quite low as only very little of the metals formed had vaporized. Most of the smoke was then of course ZnO.
I actually did save the more interesting metals (vanadium, manganese and antimony). I'll add some acetic acid to them tomorrow. :) I guess normal vinegar (10%) will do?
Thanks for the info on TiO2. I thought that it was just the high melting point.

Quote:

How did you ignite the mixes? Were they all stoichiometric (I am asking becuase of the colour being much grey-er than I am used to with my Al thermites) I.e. the V2O5 is a beautiful orange normally...


I used ordinary visco grade fuse with a little knob of black powder on the end. If that didn't work I used my propane burner.
According to my calculations all the mixes were stoichiometric though they might be wrong..
The color is probably because my Zn powder is gray compared to dark Al powder and the Zn powder makes everything gray, even in small amounts :P
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Axt
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[*] posted on 25-7-2004 at 07:35


Quote:
Originally posted by chemoleo
Axt, I tried to download the two last movies, but connection was refused.


Seems to be an ongoing problem with other movies as well, some now in uploads on FTP2 as "Axt_Movies" should work.
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[*] posted on 25-7-2004 at 14:35


Speaking of zinc, a month or so ago I got the idea to produce fine zinc powder from old flashlight batteries by electrolysing the zinc and collecting the finely deposited zinc tree on the cathode. This appeared to work well, and the amount of ampere-hours required to move all the zinc from the anode to the cathode was quite close to what I had calculated.

Unfortunately, as the wet zinc power was drying (I washed it first), I noticed it was bubbling some. By the time it was completely dry several days later, I found I had mostly ZnO instead of Zn. Apparently zinc in that finely divided of a state reacts with water, so preparing fine zinc this way does not work.
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[*] posted on 25-7-2004 at 15:34


Quote:
Apparently zinc in that finely divided of a state reacts with water, so preparing fine zinc this way does not work.


hodges- I would dry acetone with anhydrous Magnesium or sodium sulfate and then apply this to your zinc powder. If you have access to Argon or Nitrogen welding gas put the acetone soaked sludge into a tube and blow the inert gas through it. The end the tube should have a porous block to prevent the zinc from flying out. Let me know if this works.




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[*] posted on 15-11-2004 at 20:27


1) I tried V2O5/Al. it worked---but the steel "condiment cup" I used was melted through from where the top of the mixture was. I was using about 30g of mix in stochiometric porportions to the nearest g(my scale is junky and lately died:().

2) DON'T DON'T DON'T use lithium. It will likly blow up/burn your house, shed, etc down to the ground-not to mention blind you. I know----I've ignited it before ON STONE--and it left a permanent white mark on the stone.

3) In my experience the lithium forms a black nitride, which then changes to a white oxide. lithium

4) I always use magnesium ribbon from here. Unless you have lots of impurities it will always work.

PS thats where i got my V2O5 too- and a lot of my other chems.:P:D

[Edited on 11-16-04 by HNO3]
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[*] posted on 19-11-2004 at 19:18
Speed of burning depends on mesh/mixing?


Ok, couple things;
Number one is I was talking to an experienced pyro, who said one of the best and hottest thermites to make in his opinion and experience was equal amounts steel+copper+aluminum powder, and that it burns extemely hot, anyone have any experience with this mixture?

Secondly, I have also discovered that with most ignitable mixtures, the smaller the mesh the faster the burn, (this is obviously well known and I don't mean to state the obvious) however I found that a mix of 60% KNO3, 40% White table sugar and a dash of AN, when ground down to a 3500 or so mesh (3600 holes per square inch rough measured size) burns almost instantaniously, with a small whump, reminding me of flash powder, without the same amount of light. Any thoughts?

(Sorry forgot to link the above statement with the question of whether a finer mesh would make thermites burn significantly faster or not always?)

Ps: I am most happy to be able to post here, seeing as I tried posting on E&W for several weeks, and have never had any success, possibly an error with my internet sucurity...*shrugs*

[Edited on 20-11-2004 by Mickhael]
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[*] posted on 19-11-2004 at 19:30


Quote:
Originally posted by Mickhael
equal amounts steel+copper+aluminum powder


I don't see an oxidizer in this mix. Perhaps it was some oxide of copper? I've heard that thermites with copper oxides are very powerful, although the steel still doesn't make sense.
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[*] posted on 19-11-2004 at 19:43


Erm...
Number one is not a thermite, just a flamable(?) mix of powdered metal powders. And the second mix is not a thermite either just modified smoke powder.

I think I have the same problem on roguesci, my posts take a few weeks to appear, so by the time they do they are no longer needed/relavent.

Today I lit a small pile of magnesium pieces, just for kicks, made by drilling a block of magnesium. I was expecting white magnesium oxide to be produced however a black material was produced that floated in the air for a few dozen seconds then settled to the ground. Was this magnesium nitride? The only white product produced was very small and stayed on the block of wood where the magnesium was ignited.
I must say, I love my UV blocking goggles:cool:. I watched the magnesium burn directly and I did not get those weird "black spots" in my vision after. The only thing that ever left those "blackspots" in my vision when I was wearing thoose goggles is when a tiny piece of plaster incendiary caught 2' from my face while going at it with a blowtorch. It only caught after going at it with the propane torch for 5 min.:o




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[*] posted on 19-11-2004 at 20:08


As for the mixture of metals look at the thread on Bi-metallic fuse. That covers mixtures of metals that produce very high temperatures without the need for an oxidizer.



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[*] posted on 20-11-2004 at 07:19


i have recently tried PbO/Al mixture of metals even though it did burn very fast, it was not what i expected, i heard that it explodes in the open but this did not happen, i have the correct ratios mixed which were 3 moles of PbO and 2 moles of Al and they were a quite fine powder, could somebody tell me if it actualy does explode or is this just a myth,

[Edited on 20-11-2004 by boris_73]
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[*] posted on 20-11-2004 at 14:42


Are you sure it wasn't PbO2 that reacts explosively with Al vs. PbO?
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[*] posted on 21-11-2004 at 04:15


i know i was thinking that or it might be Pb3O4
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chemoleo
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[*] posted on 2-1-2005 at 21:31
Silicon Dioxide thermite


Today this was tried, in stoichiometric proportions, i.e. 54 g Al and 180 g SiO2, according to 3 SiO2 + 2 Al --> 3 Si + 2 Al2O3.
1. SiO2 as in quartz sand, >0.1 mm grains
2. SiO2 as from pottery supplies (fine powder), seemed a little wet though
3. SiO2 as from pottery supplies, fine too, and dry, but purity not known.

Using 400 mesh Al, none of the thermites worked! Not even 5 sparkling candles tied together, or direct ignition with a Bunsen burner, or a NaClO3/Al mixture (which is very bright and hot). None of them.
I am quite baffled by these results, in the light of a method in Jander&Blasius on the preparation of silicone using quartz sand.

Then, I remember using the reaction product from burning silicone (which is SiO2 with impurities), and that did seem to work sluggishly (see above).

I would have assumed that using the pure substrate would yield better results, but this... hmm.

Any ideas? One thing I will do is to 1) precipitate SiO2 from waterglass, dry and 2) dry the existing pottery supplies SiO2, and try again. But I very much feel that this won't work - having made so many thermites to this point, this seems the most reluctant one :(




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[*] posted on 2-1-2005 at 21:54


Sulfur. Schlessinger writes of 90 g sand, 100 g Al powder, and 120 g S in a crucible which is in sand. It is ignited with Mg powder and a Mg ribbon.

Henderson and Fernelius use only 90 g S, and ignite with a 1:10 w/w Al/BaO2 "starting mixture", also with Mg fuse. Their compact 1935 book "A Course in Inorganic Preparations" will be appearing soon, I scanned it earlier today.

Um, it should be pointed out that this will of course produce a lot of SO2, and adding acid to break up the sulfide slag will produce H2S.
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[*] posted on 5-1-2005 at 23:06


One of the main uses for thermites is too melts things, and that is what I want to do. And I'm thinking the slower the thermite burns the more heat will be transfered to the object. I've made CuO/Al and that burns way too fast, but I'm thinking if I cast it it might slow it down. I heard somewhere (I think it maybe the dreaded Anarchist's cookbook), that you could add plaster of paris to mould thermite. Im going to add 10% plaster of paris to a CuO/Al mix (4:1), wet and pour into a small mould and set. To ignite i'll use S/Al 2:1.

[Edited on 6-1-2005 by evilgecko]
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[*] posted on 6-1-2005 at 03:21


The amount of heat liberated should only depend on the quantity of thermite and how much heat is liberated per mole of reactants.
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