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Author: Subject: Exotic thermites & analogs
Mr. Wizard
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[*] posted on 6-1-2005 at 09:33


Strictly speaking neutrino's reply is correct. The heat released is determined by the quantity and type of the reactants, but the rate at which the heat is released does play an important role in it's use, as does the physical properties of the reactants, both during and after the reaction. Iron oxides with Al tend to be slower and have higher melting point components than say Copper Oxide and Aluminum. There is also the difference between heat and temperature which many confuse.



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evilgecko
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[*] posted on 6-1-2005 at 15:03


I have noticed that if you add more aluminium that neccecary it slows down the reaction, and more heat is directed onto the surface it is on, than if it was fast and most of the heat went into the atmosphere. Maybe this is because the molted iron has time to fall onto the surface and melt it
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optimus
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[*] posted on 20-1-2005 at 09:04


I have a few chemicals which I don't presently have any use for. Zirconium Oxide, and Cobalt Oxide. Could I make thermite with these?

Are there any uses for Gallium metal other than to look at?
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neutrino
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[*] posted on 20-1-2005 at 11:20


You could make a thermite from aluminum and the cobalt oxide, but zirconium oxide would be very difficult because the reaction releases little heat and would be hard to get self-sustaining.

As for gallium, you could sell it on eBay and get a decent price or add indium and bismuth to get field’s metal, an eutectic alloy that melts in hot water.
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optimus
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[*] posted on 21-1-2005 at 07:59


Thanks for the reply :D

Would anyone care to suggest a ratio for the Cobalt thermite? Would the Zirconium thermite be worth persuing? Would it be possible to convert the oxide to zirconium metal?

Please, forgive my lack of knowledge.
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The_Davster
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[*] posted on 21-1-2005 at 11:49


Use 2.4g of Al per 10g of CoO. This is the stoichiometric ratio.



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[*] posted on 28-1-2005 at 02:11


Thank you. I shall give it a go.;)
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Quince
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[*] posted on 24-2-2005 at 21:40


Thermite/AN Propellant

http://flux.aps.org/meetings/YR01/SHOCK01/abs/S590003.html
Anyone able to access the full text? I was unable to locate it through my university's e-journals access.


Pb3O4 Synthesis

I've read it can be made by adding sodium hydroxide to lead nitrate. Two questions: can I substitute calcium hydroxide for this, and is it reasonable to make lead nitrate from elemental lead (my reagents are very limited: concentrated H2SO4, very weak HNO3, 35% H2O2, NH4NO3). Or is there a better way to make Pb3O4?

[Edited on 25-2-2005 by Quince]




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neutrino
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[*] posted on 25-2-2005 at 07:38


This looks like a precipitation reaction, which means that you’d need a soluble hydroxide (Na, K…). There was another thread here about dissolving lead for the purpose of making PbO<sub>2</sub> electrodes, look in that for advice.
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Quince
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[*] posted on 25-2-2005 at 20:06


OK, I posted in that thread.

About my other question. I don't know how they get propellant from thermite and AN. Also, I had read somewhere that propellant can be made from 90% AN and 10% polyurethane, but when I tried that it wouldn't ignite from a sparkler (just smoked while the sparkler was heating it)...

[Edited on 26-2-2005 by Quince]




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neutrino
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[*] posted on 25-2-2005 at 20:11


What exactly do you mean by ‘propellant’? Thermite reactions give off a good deal of heat and keep a large part of it in the metallic product. Ammonium nitrate is an oxidizer. You don’t really get anything by mixing a thermite mix and AN.
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Quince
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[*] posted on 25-2-2005 at 22:03


Well, did you look at the link? Here it is again:
http://flux.aps.org/meetings/YR01/SHOCK01/abs/S590003.html




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neutrino
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[*] posted on 1-3-2005 at 05:21


Ah, there was also polyurethane in there as a fuel. My guess would then be that the AN + PU = propellant, the thermite is just there to increase the temperature and thus the pressure. I wonder how it performs?
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Mr. Wizard
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[*] posted on 1-3-2005 at 10:00


I don't see why using Calcium Hydroxide with Lead Nitrate wouldn't yield a precipitate. You start with a soluble Lead salt and a slightly soluble Calcium salt and you end up with an insoluble Lead precipitate and a soluble Calcium salt Ca (NO3)2. It may take a little time for this to react, as the hydroxide ( CaO actually) won't all dissolve immediately. Keep contact with air to a minimum while it is sitting, as the Calcium hydroxide will pull CO2 out of the air and form CaCO3 (chalk) and precipitate. It looks interesting. You will even be able to recycle the nitrate.
BTW my old 1958 chemistry set book always used CaO (lime) dissolved with Na2CO3 (washing soda) as a source of Sodium Hydroxide. The precipitate was CaCO3 (limestone).




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[*] posted on 8-3-2005 at 20:50


how fine does the aluminum have to be in a thermite Al/Fe203 mix?
is it possible to use bits of aluminum cut up by scissors? theyre still pretty small :)?
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[*] posted on 9-3-2005 at 23:43


Mine were smaller and it still didn't work.

I finally found Al powder (they call it aluminum bronzing powder) in a paint supply store. Try Google's Local Search, and type in paint supply.




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[*] posted on 11-4-2005 at 10:28
Magnesium iron thermite video


Oh yeah, just remembered I had this on hand...might as well post it here. :P

http://www.abymc.com/Video/Thermite.avi 2.1MB DivX.

That was uh....70 grams?

Tim
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[*] posted on 11-5-2005 at 12:43


Cu2O + MgAl
http://www.abymc.com/Video/CuThermite.avi

Burn rate seems pretty normal. I'll note I used 3:1, not 7:1 that just doesn't look right.

Not shock sensitive, as near as I can tell.

Tim
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[*] posted on 11-5-2005 at 16:48


Cu2O or CuO?

If it is Cu2O, then the ration of Cu2O vs Al is nearly 8 to 1 if stoichiometry is maintained.

I tried this once (see above), and got a nice regulus of Cu from it.




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[*] posted on 22-5-2005 at 12:22


Burned a packet of about 5g CuO + MgAl today - it didn't explode (suprising, as it burns so very hot in an open pile!), but it did burn jetwise with a nice volume of smoke and one joyful side-effect - all the material in the path of the flame was metallized, both mineral and organic coated with a dark pink layer. I'm thinking someone like Cyrus would like to know this.. ;)

Tim
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[*] posted on 30-5-2005 at 08:01


Tested few Mg thermite mixes few days ago as I finally got some Al and Mg powders.

http://koti.mbnet.fi/otto2000/Mg_Pb3O4_8g_210505.MOV
http://koti.mbnet.fi/otto2000/Mg_S_2g_210505.MOV

Also tested 3g Mg/PbO2, which was more powerful than the Mg/Pb3O4.

Btw. Zn/oxide mixes seem to create quite fine metal powders that are easy to purify (ZnO dissolves very nicely in acetic acid as chemoleo mentioned, and you get Zn-acetate which can be used to make for example Pb-acetate). I have made lots of Sb and Mn powders that way. Vanadium powder is quite nice too. :)

Here's also the file about the properties of different thermite mixtures (I think this is the one) if someone doesn't have it. It's quite interesting.
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[*] posted on 2-6-2005 at 23:53


Quote:
Originally posted by Boob Raider
(I miss those days when I could buy kilos of hexamine as camp fuel)


It's still available in 10lb buckets. ;)




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[*] posted on 3-6-2005 at 01:24
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why does everyone call it thermite? I recall the spelling is just Thermit? (for the trade name) otherwise there is no such name as thermite.
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[*] posted on 10-8-2005 at 07:09


Would Al foil ground up in a coffee grinder be fine enough for thermite?
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neutrino
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[*] posted on 10-8-2005 at 07:47


Yes.
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