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Author: Subject: Exotic thermites & analogs
Nixie
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[*] posted on 11-4-2007 at 20:08


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




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Aqua_Fortis_100%
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[*] posted on 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%]




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12AX7
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[*] posted on 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




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Aqua_Fortis_100%
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[*] posted on 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%]




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[*] posted on 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...




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egloskerry
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[*] posted on 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?
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12AX7
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[*] posted on 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




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egloskerry
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[*] posted on 19-4-2007 at 18:34


Mg burns at above 2000C though.
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12AX7
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[*] posted on 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




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mrjeffy321
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[*] posted on 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.
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[*] posted on 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]
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[*] posted on 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.
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mrjeffy321
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[*] posted on 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.
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[*] posted on 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).



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egloskerry
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[*] posted on 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.
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[*] posted on 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.




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[*] posted on 23-4-2007 at 06:48


hi,
what would u say about P4O10 + Al ? would it work?
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12AX7
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[*] posted on 23-4-2007 at 07:12


Doesn't P4O10 sublimate before Al ignites?

HPO4 could do it, with some hydrogen though.

Tim




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[*] posted on 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.



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[*] posted on 23-4-2007 at 08:05


maybe i could use black powder to ignite it?do u think it works?
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[*] posted on 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.



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[*] posted on 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




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egloskerry
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[*] posted on 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]
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[*] posted on 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.
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[*] posted on 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




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