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Author: Subject: Exotic thermites & analogs
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[*] posted on 26-6-2010 at 03:47


To Anders Hoveland:
Cu sulfate pentahydrate makes a nice thermite/flash with Mg. It is possible that its power is also given by CuO formed in situ reacting with Mg, that wouldn't be possible with MgSO4.
About Ag2O2, here it is made by reacting persulfate with Ag nitrate http://www.youtube.com/watch?v=1_a81M9p2so.
Quote:
I wonder if adding some NaOH to thermite would boil elemental sodium off in the absence of air.

3NaOH 4Al Fe2O3 --> 3Na 1.5 H2 2Al2O3 2Fe

A thermite made with Mg and NaOH makes some sodium metal as described on this forum. Although Al is less reactive I don't think Fe2O3 is really needed once the reaction starts.

To Skyjumper:
Quote:
I hope you did that in a hood. Lead vapor/ compounds in the air are not good for you. At all. I highly doubt Cu/S is friction sensitive, or at least that friction sensitive. Your plastic probably was not clean.

I'm aware of the dangers of lead. All the tests were 0.25 gram at most and were done outside avoiding the fumes. About Cu/S I think argyrium is right, it ignited due to static electicety, also because fire was brief, like only the suspended S particles caught fire.
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[*] posted on 26-6-2010 at 09:32


Quote:
Cu sulfate pentahydrate makes a nice thermite/flash with Mg. It is possible that its power is also given by CuO formed in situ reacting with Mg, that wouldn't be possible with MgSO4.


What is the ratios of this mix?
Knowing that CU Sulfate contains a lot of water, does it have to be dried well before use?
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[*] posted on 26-6-2010 at 16:40


Ag2O2 + 4Cu --> 2Ag + 2Cu2O
3Ag2O2 + 4Fe --> 6Ag + 2Fe2O3
How is this for an unusual thermite reaction?
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[*] posted on 27-6-2010 at 13:36


Anders, whats the energy release? I have a huge list of thermit (Goldschmidt) reactions here and cannot find it.

I rather think that Pd:Mg is a good intermetallic, I know for a fact that it is being looked into as a reactive liner for Shaped Charges, something to do with it 'burning' and 'punching' through at the same time.




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[*] posted on 27-6-2010 at 15:57


Another idea:
3NiF4 + 2B --> 2NiF2 + Ni(BF4)2

NiF4 is an unusual +4 oxidation state. It cannot be made by directly oxidizing NiF3 with fluorine. The B--F bond is very strong, so it would be expected that this exotic thermite would be extremely violent.

Alternatively
6NiF3 + 2Al --> 6NiF2 + Ni(AlF4)2

Aluminum Trifluoride has strong 3-center bonding which causes it to be refractory. Even its melting point is 1291 °C, so despite how hot the thermite gets, AlF3 would stay solid. This should be an interesting thermite because no gas is given off, preventing any violent spurting of the molten reactants, and preventing any heat from escaping though vaporization.
AlCl3, boils at a much lower temperature; it has a melting point of only 192.4 °C, which indicates that the bonds a covalent, but there is no 3-center intermolecular bonding.
If you watch a thermite that uses aluminum powder and FeCl3 , you will see a lot thicker smoke as the AlCl3 vapor formed starts cooling. You can buy FeCl3, and all sorts of other goodies here: http://www.google.com/imgres?imgurl=http://unitednuclear.com...

I saw an excellent site that had a video of FeCl3 thermite, but am unable to currently find it.

K2MnF6 + 2Al --> K2(vapor) + 2AlF3 + Mn
2K2MnF6 + 2Al --> 2KF + AlF3 + F2(gas)

As you can see, if this thermite is not well mixed, part of the reaction will give off elemental vaporized potassium, and other regions of the reaction will give off fluorine gas. This should be quite impressive, as the two gases will react energetically above the molten thermite reaction! As Manganese has a boiling point of 2061 °C, non of this metal will be vaporized. KF has a boiling point of 1505 °C. Making K2MnF6 is discussed elesewhere in this forum, and is not too difficult. I hope this provides some interesting exotic thermite ideas and that someone will try one!


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[*] posted on 27-6-2010 at 16:16


IIRC FeCL3 is used in etching PCB's. Look in Maplins or something.



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[*] posted on 8-12-2010 at 03:20


Does anyone know how I'd go about separating boron (provided I've actually made any) from the crud left over after the reaction of 13.5g dry borax, 11g Aluminium and 10g Sulfur? I'd just made some silicone in a similar way and thought I'd have a try at boron (but couldn't be bothered making B2O3 first :P)
It lit easily and burned smoothly and quickly making a tall orange flame, it was in a graphite crucible and the products stayed glowing in the crucible for quite some time, they're sitting outside now cooling down.
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[*] posted on 24-4-2011 at 08:00


Quote: Originally posted by Polverone  
Many oxides/salts of less reactive metals can react vigorously when mixed with an appropriate quantity of magnesium or aluminum and initiated by high temperatures (or, in some cases, by a detonator). The most common of these mixtures, of course, is aluminum and iron oxide.

I've experimented with a few other different mixtures. Anhydrous CuCl2 and aluminum is easy to ignite, though not terribly vigorous. I was able to wrap some CuCl2 powder in aluminum foil to make a tube and ignite the tube at one end with an alcohol burner. Combustion progressed with a small amount of pinkish flame (I would have expected green or blue, but it was pink) and considerable smoke, with solid copper being deposited. CuCl2 and 300 mesh aluminum powder burned quickly.

Flour-fine CuO from a ceramics supplier burned with extreme vigor with 300 mesh aluminum in a stoichiometric ratio. I ignited one charge of about 30 grams at night with a hot aluminum/sulfur ignition mixture. The thermite mixture was in an aluminum can with the top cut off and the igniter laid on top. The CuO/Al burned in a fraction of a second with a hearty "whump!" and shot glowing debris (likely the igniter slag) 10 meters in the air.

A 50 gram charge of the same mixture was initiated in the daytime with 2 grams of HMTD. There was a satisfying flash and explosion, and a large cloud of brownish smoke (vaporized copper mixed with aluminum oxide) rose above the test site. It is interesting that this mixture yields *no* permanent gases at STP yet exploded with sufficient force to make the plastic stand holding the charge vanish without a trace.

I have oxides of tin and chromium on hand, which I hope to try at some point in the future. I would also like to try lead salts/oxides, though I fear excessive sensitivity with these, and also with silver salts/oxides, though I fear sensitivity *and* price with them.

Have any other experimenters here wandered off the beaten path of "standard" thermite?


Try a fluropolymer like PTFE/Teflon and Aluminium!




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[*] posted on 24-4-2011 at 15:42


Quote: Originally posted by Polverone  

Flour-fine CuO from a ceramics supplier burned with extreme vigor with 300 mesh aluminum in a stoichiometric ratio. I ignited one charge of about 30 grams at night with a hot aluminum/sulfur ignition mixture. The thermite mixture was in an aluminum can with the top cut off and the igniter laid on top. The CuO/Al burned in a fraction of a second with a hearty "whump!" and shot glowing debris (likely the igniter slag) 10 meters in the air.

Föredrag vid PYROTEKNIKDAGEN [Pyrotechnic Day] 1971
Stockholm den 10 maj 1971
Aluminium Powders For Explosives And Pyrotechnics
Gustaf Windqvist


Extracted from — Aluminium powder in explosives

As can be seen from the name of the article, I have tried to deal only with
aluminum powder for explosives.

Mainly I have tried to do this because I do not have any first-hand experience of
explosives and in the audience there is a number of chemists from the explosives
industry, who could contribute to the discussion of the use of metal powders in
explosives and pyrotechnics

As a final vignette I might be permitted to show a rather funny picture of an
explosion in water, which I had the improbable luck to take with a common camera
more than 20 years ago.

At the company we were playing with certain thermite charges, who were
supposed to have a certain effect in undercooked water streams. One of these charges
contained atomized Aluminium powder A 80 and copper oxide in an equivalent mixture.
If such a charge was lighted by a generator-gas match in air, it burned quickly and if it
was lighted by No 8 detonator it detonated and you got a beautiful copper-cloud in the
air. We thought that if it was used under water, with a generator-gas match, it would
burn quickly, but to our surprise, if not a pure detonation, we got a very fast deflagration
I succeeded in taking this photograph of the water-bubble, which emerged just before it
burst You can see a tendency of bursting on the top, and the white dots are
white-glowing charge. See figure 3.


[Two possibilities come to mind.
The temperature of the reaction may have been sufficient to dissociate water into
hydrogen and oxygen, which then explosively recombined.

Or this may be a classic if poorly understood “liquid metal water explosion.” Aluminium
and water can be detonated.]

The poor quality picture is not worth posting. /djh/
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[*] posted on 24-4-2011 at 15:59
That quick thermit's


Extracted from:—

ALUMINIUM AS A HEATING AND REDUCING AGENT.
BY DR. HANS GOLDSCHMIDT AND CLAUDE VAUTIN.
The Journal of the Society of Chemical Industry (6)17:543-545
June 30, 1898

[I did back when an OCR of the complete article, after I check to
see if that I have not already posted it here.... I may be back.]

(See also pp. 584 and 612.)

Action of Aluminium on Oxides.—Copper oxide (cuprous or cupric) mixed with
the correct proportion of aluminium powder for reduction, and heated gradually,
reacted suddenly, with a report like that of a gun. The glass tube was shattered
and small copper shot were found. With an excess of aluminium, the residue was
an aluminium bronze. Silver oxide was similarly attacked. Beryllium was also
reduced at a red heat, but quietly, and with only slight incandescence. Calcium
could be partly reduced from lime, and calcium alloys could thus be readily
obtained. Strontium was reduced from the oxide with a more marked rise of
temperature. Baryta is much more readily, and is indeed almost completely
reduced, with distinct incandescence. Zinc oxide is reduced with quiet
combustion and a blue white luminous flame. Cadmium and mercury and lead
oxides also yield metal, the former quietly, the second almost at once, and the
last-named with explosion. Boron, silicon, phosphorus, and arsenic also, are all
separated in the elementary state on beating the oxide with powdered
aluminium. Iron, manganese, cobalt, nickel, and molybdenum are all partly
reduced ; in the electric furnace new compounds are thus produced.

----
Mellor — INORGANIC AND THEORETICAL CHEMISTRY
[Scanned and you know what that means!]


C. and A. Tissier 12 first noted the reduction of the metal oxides by aluminium they did
not succeed in reducing zinc or manganese oxide in this way; but they reduced iron
oxide, forming an iron-aluminium alloy; there was a strong explosion with copper oxide,
and with lead oxide, 50 grms., and aluminium foil, 2-9 grms., the crucible was broken to
pieces and the doors of the furnace blown off. Aluminium oxide has a very high heat of
formation-about 131.2 Cals., and this is equal to or slightly lower than the heats of
formation of the oxides of calcium, strontium, lithium, and magnesium, but larger than
the heats of formation of sodium, potassium, rubidium, silicon, boron, and most of the
other metal oxides. Hence, unless these magnitudes alter adversely with rise of temp. it
would be anticipated that aluminium would reduce the metal oxides at high temp. Some
such hypothesis guided H. Goldschmidt, who found that the oxides of the alkalies and
alkaline earths are reduced with difficulty by aluminium, but practically all the other
metal oxides are reduced by heating them with aluminium powder, and he obtained
either the metal, or an alloy of the metal, with aluminium, from the oxides of chromium,
manganese, iron, copper, titanium, boron, tungsten, molybdenum, nickel, cobalt,
zirconium, vanadium, niobium, tantalum, cerium, thorium, barium, calcium, sodium,
potassium, lead, and tin. he said:.............

----
I would add based on experience — manganese dioxide
for POOF!
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[*] posted on 24-4-2011 at 22:12


Quote: Originally posted by IndependentBoffin  
Try a fluropolymer like PTFE/Teflon and Aluminium!


Teflon/mg/Al can do strange things.


Study of Explosion Properties of the Mg-Al/PTFE Composition
Military Technical University, Mechatronics Faculty, 2 Kaliski St., 00-908 Warsaw, Poland

"The object of the research are explosive properties of the pyrotechnic composition consist of fine grade magnesium-aluminium powder (PAM) and highly dispersed polytetrafluorethylene (PTFE). The composition reveals high resistance to all mechanical and thermal impulses and is extremely sensitive to hot sparks and open fire. The burning rate of the composition changes from 1 cm/s to 100 m/s along with decreasing its density. Charges of the composition of density below 1 g/cm3 burn so violently, that the phenomena is similar to explosion. Charges of density above 1,1 g/cm3 burn relatively rapidly and stably. The main part of the paper concerns the research of pressure impulses in the air generating after high-rate burning of the composition of bulk density. The nature of the generated pressure impulse is not that of a typical shock wave. A rise of pressure over the distance from the point of explosion to the maximum value lasts 50-100 milliseconds, while for shock waves this factor is less than a microsecond for equivalent charges. The methods of initiation of the composition influence the shape and parameters of the pressure impulse. The explanation the nature of great changes of the composition burning rate have been proposed."

Taken from http://archcomb.itc.pw.edu.pl/downloads/01_2007.pdf


as well as

Detonation in an aluminum-Teflon mixture

A. Yu. Dolgoborodov, M. N. Makhov, I. V. Kolbanev, A. N. Streletskii and V. E. Fortov

"Detonation in an aluminum-fluoroplastic-4 (Teflon) mixture is studied experimentally. To increase reactivity, the initial mixture is pretreated in a mechanochemical activator. As a result, a mechanically activated composite is obtained in the form of thin aluminum layers in a Teflon matrix. The action of a shock wave on a composite sample initiates the steady detonation regime, in which the initial and final substances are in the condensed state. Depending on the percentage composition and density of the mixture, the detonation velocity varies from 700 to 1300 m/s for the speed of sound below 100 m/s in the initial composition. The steady detonation velocity changes insignificantly when sample pores are filled with helium instead of air. The results prove that it is possible in principle to reach the steady detonation regime in reactive condensed mixtures forming final reaction products in the solid state. "

Taken from
http://www.springerlink.com/content/5711q7j73392n47g/
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[*] posted on 25-4-2011 at 06:56


I wonder how the pressure rise time, max pressure, pressure duration, etc. are affected by using a highly brisant initiator compared to less brisant ones?

E.g. a tubular Al/PTFE tube form initiated from a cylindrical core of HMX (highest VOD) vs. PETN (moderate VOD) vs. TNT (lower VOD).

[Edited on 25-4-2011 by IndependentBoffin]




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[*] posted on 25-4-2011 at 08:33


Quote: Originally posted by Polverone  

Flour-fine CuO from a ceramics supplier burned with extreme vigor with 300 mesh aluminum in a stoichiometric ratio. I ignited one charge of about 30 grams at night with a hot aluminum/sulfur ignition mixture. The thermite mixture was in an aluminum can with the top cut off and the igniter laid on top. The CuO/Al burned in a fraction of a second with a hearty "whump!" and shot glowing debris (likely the igniter slag) 10 meters in the air.

Extracted from :—

CJ Murray, A Payne, S. Courtley
Some Aspects of Special Effects Pyrotechnic and Explosives
practice in the Australian Film Industry
Twenty-Eight International Pyrotechnics Seminar
Adelaide South Australia November 2001

7) "HE" Simulators- Copper Oxide/Aluminium powder in various
masses – 5,100,200 & 600 gram lots in fibreboard cylindrical
containers, with squib initiation { see below }

The "HE" copper oxide/aluminium composition is used in a number
of applications; some of them being:

1) As a base charge in dishpan mortars to propel dust, cork,
peat moss etc. and also to provide flash. If dry peat dust is used in
mortar, then the "HE" comp. will usually fireball the dust within the
plume of debris – this can be seen clearly in " Thin Red Line"
2) When " HE" comp. is used in small quantities as an igniter for
relatively large quantities of single base smokeless powder, the
effect is a large smokeless fireball, with a green tinge around its
edge. Various mortar geometries produce fireball shapes from
tongue shaped to spherical. Used extensively on "Farscape" indoor
sets.
3) For "Farscape" action exteriors, a 200g. "HE" charge may be
buried in sand and surmounted with a 500 g. bag of AS30
smokeless powder – the effect is a brilliant orange flash with a
brief, large green fireball and a burst of brown/red smoke.
4) Various arrangements of "HE" and Smokeless Powder also
provide cannon muzzle flashes, tongue flames and other effects.


5) The "HE" comp is also very effective as an igniter and
propellant for liquid fuel fireballs. Super petrol and iso- propyl
alcohol are the fuels in general use for this purpose.

Exemplary footage from the following productions illustrates the
use of some of the items and compositions outlined above;


"Thin Red Line" ( 1998 )

Mortar round impacts and heavy artillery bombardment.
Dishpan mortars with "HE" as flash agent and propellant, peat dust
ignition in plume.
"HE" as flash agent for high explosive events

"First Daughter ( 1999 )

Rocket projectile striking limousine and pergola.
"HE" as flash agent in combination with small dishpan mortar with
"rubber ball" charge and benzoyl peroxide as fireball agent.

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[*] posted on 26-4-2011 at 21:47


I'm curious, has anyone played with burn rate/thermite density? I saw allusions to the effects but unless I missed a post there was no data.



Also, I've been having a hard time finding data on this but I'm wondering about impact initiated thermites involving iron hydroxides and aluminum.

I've heard that there has been at least one instance where a fuel truck and gas station caught fire when the aluminum nozzle of the fueling truck struck the rusty steel entrance of a gas stations underground fuel tanks, causing a thermite spark and subsequent ignition. I have not found reports of this online... I'm not sure if it is true or not.

Has anyone heard of this/have a credible source for this?

I have found some articles about impact ignition of iron oxide/aluminum thermites one which gave interesting results is below.

Kinetic study of thermal- and impact-initiated reactions in Al–Fe2O3 nanothermite

http://www.sciencedirect.com/science?_ob=ArticleURL&_udi...




In experience, if two pieces of hardened steel are rusted to have a nice even layer of hydrated oxides; they will emit a sharp Crack and very bright, but focused, light when struck against each other with a piece of aluminum foil in between. The noise is highly reminiscent of a toy cap being set off via impact.

If struck against each other with a glancing impact they will emit a much softer noise but produce a much more brilliant spark.

I'm wondering if it is possible the compression of the two steel surfaces is perhaps able to form a tiny abnormal (dare I say exotic?) thermite reaction in which the aluminum fully reduces iron hydroxide into hydrogen and iron. The noise it makes is a very sharp, it has a quality I associate with substances detonating.


I'm wondering why the noise is so sharp.

My thoughts so far have been the sharp noise of the direct impact could be caused by super heated hydrogen reacting with the air immediately around the impact, or that the tiny point of ignition is actually a true detonation.

The article above gives a maximum observed flame front in a Fe2O3/Al thermite as being up to 400 meters per second when impacted. Obviously they have a more scientific set up then a set of rusty ship bearings... but at least there is the possibility that an iron oxide thermite can burn supersonically (my understanding is a detonation in a technical sense is a flame front which travels over the speed of sound?)

There are a number of studies on the possibility and occurrence of thermite sparks due to the impact or friction between aluminum and iron hydroxides but I have yet to find relevant data on the maximum speed of observed flame fronts for said hydroxides.


Thoughts?
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[*] posted on 30-6-2011 at 10:14


Quote: Originally posted by Neil  


as well as

Detonation in an aluminum-Teflon mixture

A. Yu. Dolgoborodov, M. N. Makhov, I. V. Kolbanev, A. N. Streletskii and V. E. Fortov

"Detonation in an aluminum-fluoroplastic-4 (Teflon) mixture is studied experimentally. To increase reactivity, the initial mixture is pretreated in a mechanochemical activator. As a result, a mechanically activated composite is obtained in the form of thin aluminum layers in a Teflon matrix. The action of a shock wave on a composite sample initiates the steady detonation regime, in which the initial and final substances are in the condensed state. Depending on the percentage composition and density of the mixture, the detonation velocity varies from 700 to 1300 m/s for the speed of sound below 100 m/s in the initial composition. The steady detonation velocity changes insignificantly when sample pores are filled with helium instead of air. The results prove that it is possible in principle to reach the steady detonation regime in reactive condensed mixtures forming final reaction products in the solid state. "

Taken from
http://www.springerlink.com/content/5711q7j73392n47g/


It's in russian but with a translator it's do-able to get the big picture.

Attachment: Volume 81, Number 7, 311-314, DOI 10.11341.1944069.PDF (246kB)
This file has been downloaded 962 times




.....ejuu....................................................................Ffg..............................g.............
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[*] posted on 6-7-2011 at 23:01


Quote: Originally posted by The WiZard is In  

Beryllium was also reduced at a red heat, but quietly, and with only slight incandescence. Calcium could be partly reduced from lime, and calcium alloys could thus be readily obtained. Zinc oxide is reduced with quiet
combustion and a blue white luminous flame. Boron and silicon are both
separated in the elementary state on beating the oxide with powdered
aluminium.


It is interesting that aluminum-oxygen bonds are so strong. I would not have thought aluminum could reduce beryllium oxide. I suppose aluminum is in an ideal place on the periodic table. If it were to the left or lower down, the bonding would be more ionic and less favorable (as aluminum can reduce sodium oxide, oxygen has a smaller atomic orbital and it is less favorable for it to hold a double negative charge). If it were above or to the right, the element would not be as electropositive. So it could be said that aluminum is in a middle spot where it experiences the best of both worlds, in terms of being able to reduce oxides of other elements.




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[*] posted on 16-8-2011 at 11:11


Aluminium and sulfur should give you one hell of a burn.
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[*] posted on 16-8-2011 at 12:43


Quote: Originally posted by White Yeti  
Aluminium and sulfur should give you one hell of a burn.



S-l-o-w burn.


Tell the WiZ (donald j haarmann)
American Fireworks News #38
http://www.fireworksnews.com/
November, 1984.

USES FOR PYROTECHNICS YOUR MOTHER NEVER TOLD YOU ABOUT
THE PYROTECHNIC BLANKET

Because steel reinforced portland cement concrete bridge decks are susceptible
to premature and severe corrosion damage during use caused by the
absorption of water and salt solutions, Internally Sealed Concrete was
developed. Wax beads are uniformly distributed throughout. The portland
cement concrete mix at the time of mixing. After the concrete cures, the wax
beads remain as such in the concrete. To become effective the beads must be
melted so that the wax can flow into the pores, capillaries and cracks of the
concrete. And therein lies the problem; how to heat up a bridge!

Electric blankets were tried with little success. Therefore as "Pyrotechnic
materials are portable self-contained energy sources that can produce large
quantities of heat", the pyrotechnic blanket was developed.

Because of cost requirements, a maxim heat output for minim money input was
desired., therefore a hybrid system of iron and aluminium powders (fuel) and
sulphur (oxidizer) was used. Finely divided aluminium and iron powders each
react with sulphur (2 Al + 3 S = Al2S3 and Fe + S = FeS) to produce producing
1470 and 455 BTU per pound. The reaction temperature for the sulphur and
aluminium being 1200oF (650oC), the iron sulphur reaction temperature is
510oF (275oC). By controlling the mixture, temperatures between these limits
can be produced. Maximum use of aluminium was preferred due to its higher
exotherm and the resulting better thermal cost efficiency. However, iron was
desired to reduce both the maxim temperature and the burning rate of the
pyrotechnic, thereby increasing the length of time heating would take place.

The composition adopted as representing the best blend of fuels (powdered
metal), oxidizer (sulphur) and fillers was the following:

Sulphur 39.06
Medium Sand 14.85
Carbon Black 7.62
Aluminum 12.50
Iron 25.97

The ingredients were mixed and then heated until the sulphur melted, with the
resulting, mass being allowed to cool in molds.

Significant savings in" material costs was obtained by using reclaimed and re-
processed aluminum scrap (cans) obtained from Alcoa. ($0.50 lb)

-----------
There is, of course, a large problem with this process; the end products of the
reaction between both aluminum and iron with sulphur are sulphides. The iron
(ferrous sulphide) is of no concern. However aluminium sulphide is another
animal, a rotten smelling one at that! For aluminium sulphide and moisture will
react to form aluminum hydroxide, and good old hydrogen sulphide! One could
foresee. both esthetic and health problems, as hydrogen sulphide is more
poisonous than hydrogen cyanide gas!


FHWA-RD-79-144
Self Contained, Expandable Pyrotechnic Blankets for Heat-Treating internally
Sealed Concrete.
75 pages;
NTIS PB82-108820
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White Yeti
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[*] posted on 10-10-2011 at 11:41


Wiz:

I performed this reaction not too long ago. It's vigourous when the elements are in fine powder form. It throws sparks all over the place and gets hot enough to melt through iron. The mass of molten ceramic is as tough as an annealed piece of aluminium oxide and it smells of hydrogen sulphide. Great stuff if you want to fumigate your neighbourhood:)

I never thought of using iron powder to help the reaction along- it does need a lot of activation energy.

I'm not sure if this would classify as a "thermite" per say, but it's a vigourous redox reaction involving aluminium that throws molten metal all over the place and renders your garden uninhabitable for a few hours.

It's by far my favourite reaction involving aluminium because the end product can be used to make an H2S generator while the molten iron from thermite can't be used for anything at all.

I am aware of the dangers mind you. Disposing of the waste is no problem when the end product is a rock, not a powder.




"Ja, Kalzium, das ist alles!" -Otto Loewi
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AndersHoveland
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[*] posted on 29-11-2011 at 14:45


Al/CuO thermite releases roughly 5.2 kcal/cm3 or 1.2 kcal/g.
Al/KClO4 [flash powder] releases roughly 6.8 kcal/cm3 or 2.7 kcal/g.
Al/teflon releases 4.8 kcal/cm3 or 2.3 kcal/g.
Compare these to HMX, which releases roughly 2.8 kcal/cm3 or 1.6 kcal/g. A gram of HMX actually releases more energy than a gram of Al/CuO because the aluminum and copper atoms weigh so much, but the a cubic centimeter of the Al/CuO will still release more energy than the same volume of HMX. Of course the HMX releases its energy much faster than any thermite mix.
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[*] posted on 28-12-2011 at 15:49


Is there any way to perhaps dilute an extremely fine powder Thermite mixture of CuO+Al to the point where it won't react explosively? I'd like to yield pure copper from a CuO+Al Thermite, and all I have is extremely fine powdered ingredients which react violently. Could I add a little bit of sand to the mixture to raise the ignition temp a bit? I can't think of any way the components of sand would react hazardly with Al, Al2O3, CuO, or Cu.
Could Sand work to slow down the reaction enough to have a contained reaction with a solid yield?
If so, I would imagine I should also grind down the sand to a somewhat fine mesh before adding. Correct? Or would this jsut discourage the reaction very little?

[Edited on 28-12-2011 by Spart]

[Edited on 29-12-2011 by Spart]
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Neil
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[*] posted on 29-12-2011 at 05:59


CaF,SiO2,NaCl you can add a lot of things to dampen the reaction. A packed (!don't pound on it!) thermite will also burn slower then a fluffy one.


It takes a lot of Silica sand (higher MPP then ground glass) to dampen CuO + Al. You'll make a lot of glass gas.

To add to Anders - While thermites may store more energy then some mixtures, the massively high heat of fusion for the reaction products eat up most of the energy produced, giving a rather pathetic and near useless amount of free usable energy.
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[*] posted on 5-1-2012 at 05:38
Energetic Thermite s


Intro:
Happy New Year!
Question from a newbee:

Searching for a "greener" energetic (non-Kclo3) reaction- What post reaction fumes are produced from thermite: CuO / MgAl or Al formulas, posing respiratory or environmental issues? Any other outstanding issues?




blastron
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[*] posted on 5-1-2012 at 06:53


Read the whole thread and I promise you will find your answers.
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[*] posted on 1-2-2012 at 12:15


2CrO<sub>3</sub> + 3MgAl => Cr<sub>2</sub>O<sub>3</sub> + 3MgO + 3AlO

then 3Cr<sub>2</sub>O<sub>3</sub> + CrO<sub>3</sub> => 5CrO<sub>2</sub> + O<sub>2</sub>
O<sub>2</sub> + MgAl => MgO + AlO
while
2Cr<sub>2</sub>O<sub>3</sub> + 2Al + 3Mg => 4Cr + Al<sub>2</sub>O<sub>3</sub> + 3MgO


by this time It has to be 1000s of degrees C, so..
5CrO<sub>2</sub> + 4MgAl => 2Al<sub>2</sub>O<sub>3</sub> + 4MgO + 5Cr

Flash and thermite..might spontaneously ignite though...




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