Sciencemadness Discussion Board - Exotic thermites & analogs

Exotic thermites & analogs

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12AX7 - 3-10-2008 at 20:00

All aluminum-silicon alloys present as a mixture of dentritic aluminum and flat silicon plates. The eutectic is something like 15%, so stuff below has silicon as fine plates when the eutectic freezes around whatever aluminum crystallized from it. Above, fat silicon crystals form first, and without additives, they are visible by eye on a cut surface (practical hypereutectic alloys, used for forgings and abrasion-resistant castings, have grain refiners which make the crystals finer).

I've not isolated a crystal, but I gather they are generally shaped like graphite in gray cast iron; flat plates, oblate cross section, but with the notable exception that silicon is an awful lot harder than graphite, so the alloys are a bit stronger than gray cast iron.

No intermetallics form at any point, at any rate of cooling, as far as I know.

How about something more mundane, like excess aluminum producing hydrogen which was ignited by an unusual concentration (near 1%?) of phosphide? Does diphosphine usually ignite spontaneously at such concentrations? There is always a phosphide impurity, even in pure aluminum metal, it's just not that much; however, it's plainly obvious in combination with acid.

Tim

blogfast25 - 4-10-2008 at 05:59

Tim -

Phosphine: it's a possiblity but how to explain that the phenomenon isn't observed when dissolving the actual aluminium powder in HCl? A bit of a chemystery, this one...

12AX7 - 4-10-2008 at 09:44

Idunno- phosphate in the CaSO4 or stuff?

Tim

blogfast25 - 5-10-2008 at 06:54

Well, remember this post of mine, Tim? That appeared to suggest reducing P2O5 with Al is possible. And I think that's correct: even an extremely stable oxide like Ta2O5 can be reduced with Al, mainly because it's a pentoxide...

But where would the phosphate come from? Phosphate deposits don't seem to coincide with Gypsum deposits at all (presumably because of their strongly different solubilities). Most drywall must therefore be essentially phosphate free, IMHO...

Gangue accompanying the fluorite? Mine is made of clean off-grade lumps, no gangue in sight...

I guess the first step to solving the puzzle is to identify whether the gas in question is silane or phosphine... I might try that...

chloric1 - 5-10-2008 at 07:01

blogfast-If you can protect your reactive gas, then simply passing it through a heated glass tube at 400C or so should deposit a residue of red phosphorus.

blogfast25 - 5-10-2008 at 09:32

Quote:

Originally posted by chloric1
blogfast-If you can protect your reactive gas, then simply passing it through a heated glass tube at 400C or so should deposit a residue of red phosphorus.

Collecting the gas/hydrogen mixture and burning it in controlled conditions would be simpler: in the case of silane, silica (and possibly elemental silicon) would be formed. Although vapour deposited silicon would be a nice thing to see...

[Edited on 5-10-2008 by blogfast25]

mrjeffy321 - 13-10-2008 at 20:44

I have been promising to do this for months now, but I was just now able to perform Energy Dispersive X-ray Spectroscopy (EDAX) on some of my metal samples prepared through thermite reactions.

For those of you who may not know,
EDAX works by firing a high energy electron beam at a sample. The high-energy incident electrons have a chance to eject one of the inner electrons from an atom in the sample, thereby leaving a 'hole' behind in one of the atom's inner shells. An electron from one of the atom's outer shells quickly falls down into this hole, in the process releasing a high-energy (X-ray) photon. By studying the spectrum of emitted X-rays we can tell what elements make up a sample, and in what proportions. The majority of the readings will come from photons emitted at or near the surface of the sample, however with a sufficiently high-energy electron beam one can penetrate a considerable distance into the sample (on the order of hundreds of nanometers to microns deep).

I performed this analysis on small nuggets of "Silver" and "Titanium" metal which I produced via Ag2O and KClO3-boosted TiO2 thermite reactions.

The results are as follows:

Silver:

15 kV beam (large scan area, ~microns):
Weight percent: Carbon 7.29%, Magnesium 0.72%, Aluminum 0.68%, Silver 91.31%
Atomic percent: Carbon 40.25%, Magnesium 1.96%, Aluminum 1.68%, Silver 56.11%

20 kV beam (localized scan area, ~hundreds nm):
Weight percent: Carbon 11.96%, Magnesium 1.03%, Aluminum 0.74%, Silver 86.27%
Atomic percent: Carbon 53.38%, Magnesium 2.27%, Aluminum 1.47%, Silver 42.88%

Titanium:

20 kV beam (large scan area, ~microns):
Weight percent: Carbon 5.18%, Aluminum 24.78%, Titanium 70.04%
Atomic percent: Carbon 15.34%, Aluminum 32.66%, Titanium 52.00%

20 kV beam (localized scan area, ~hundreds nm):
Weight percent: Carbon 5.13%, Aluminum 23.50%, Titanium 71.37%
Atomic percent: Carbon 15.33%, Aluminum 31.23%, Titanium 53.44%

As you can see, the peaks for the nominal metal are very high, but they are not alone. There are metallic impurities in the nuggets, and apparently some Carbon is in there too somewhere (possibly just residue on the surface it has picked up over time after I first made the metal and / or all the handling I have done of it since then). The high presence of Aluminum is not surprising since Aluminum was present in the thermite reaction as the reducing agent; finding that some of the Aluminum alloyed itself with the produced metal was expected, actually it was this ratio (Aluminum to Ti) which I wanted to determine. The Magnesium in the Silver is also understandable since that thermite reaction did not really 'take off' after ignition. Instead, once ignited, the Ag2O thermite tended to 'blow itself out', thus only a small area right around the Magnesium ribbon fuse reacted.

blogfast25 - 14-10-2008 at 09:04

Hi Jeffrey,

This is very exciting (no pun intended) and somewhat unusual too.

I'm reasonably assuming that your samples of titanium are like mine and haven't been de-slagged. This is quite an important point because as you'll recall I found a substantial part of the samples (typically a few g of material) to be insoluble in a excess of hot (near BP) 32 w% hydrochloric acid (soaked for about 12 h). The residue typically weighed in at 10 - 15 w%. I always assumed that these were slag inclusions, so mainly annealed alumina but never got a chance to verify this (fusing with alkali or NaHSO4 should dissolve it I imagine).

And on the soluble part my titrometric analysis (Ti3+ + Fe3+ ---> Ti4+ + Fe2+, SCN- indicator) found roughly 80 w% of Ti. That would be broadly speaking in line with your results, assuming I'm right about the slag inclusions.

The drawback of EDAX is of course that it doesn't tell you what molecular/ionic species the element is part of. Some aluminium must be present as aluminium, but some may be present as alumina, as I suspect.

It's unfortunate that you don't have more ready access to EDAX because I feel the % of Al could be further suppressed by slagging excess TiO2 into the thermite mix, as this would push the equilibrium TiO2 + 4/3 Al <---> Ti + 2/3 Al2O3 to the right.

I once estimated the equilibrium constant K of this reaction to be103 to 104 but that doesn't really fit the high Al content. Still, the fact that we roughly use stoichiometric mixtures for this thermite and the fact that the enthalpy of reaction is quite small (- 161 kJ/mol of reduced oxide IIRW, it greatly affects K, K being larger for more negative ΔG), would favour some of the Al not being used to reduce the oxide.

The biggest headache though IMHO is the carbon content: 15 at%??? Blimey, who ordered that? I would have expected such a quantity to show up during dissolution, wouldn't you? I never saw that...

What, in your opinion could be the source? Some aluminium powder (like German Black and some pyro grades) does contain quite a bit of carbon but as far as I know mine doesn't...

Some titanox grades are surface treated (wetting agents, or silanes) and could contain some too...

If you get the chance to do some more EDAX, could I slip a sample (or two - lol) in there?

[Edited on 14-10-2008 by blogfast25]

12AX7 - 14-10-2008 at 14:42

When I got an electron microscopy and x-ray spectrum of a sample, I was told C, H and O are always there as a result of surface contamination, even freshly prepared surfaces. H and O come from adsorbed H2O, inevitable in the atmosphere, while C and H come from handling.

Tim

chloric1 - 14-10-2008 at 17:32

@blogfast-look more closely at Jeffy's data. I reread it myself for extra clarity. What became obvious to me was that the reading was off the surface and the results with the 20kv beam verses the 15kv beam do in fact show LESS carbon which leads to surface contamination as the usual suspect.

Next time you have a chance at EDAX, I would try soaking samples in isopropanol, remove the sample and ignite remaining alcohol for sample surface, vacuum dry sample, then seal in vaccum bag until testing can be commenced. Changing stochiometry to favor metal production will help minimize metallic aluminum contamination. Many of the exotic metals we wish to produce are not alkali soluble so a bath in molten NaOH might help remove or loosen alumina from sample. Alumina is quite brittle and some mechanical removal works as long as the metal is not so brittle. This is problematic with chromium as I found it qute brittle and eaily broken despite hardness. This is where one only wants to really deal with larger pieces that are not easily polverized.

[Edited on 10/14/2008 by chloric1]

mrjeffy321 - 14-10-2008 at 19:26

The Titanium nugget came from a 530 gram thermite reaction composing of a mixture of TiO2, Al, KClO3, and CaF2 in a ratio of 100 : 75 : 50 : 40. Ordinary, pure, Aluminum powder was used, not German Aluminum powder. After the reaction, the metal was removed from the rest of the slag (through hammering) and was polished to get a shiny surface with a rotary grinder and sand paper.

EDAX will not tell you the chemical compounds making up the sample, just what elements are they. But if you already have a good idea of what your sample is (for example, you know its some metal alloy, or you know its an oxide, ….) you can sometimes infer the ratios of the compounds you suspect. In this case, however, the only elements which show up are ones which we would not ordinarily expect to bond together making some molecule / compound, so I infer they are in their metallic state alloyed together.

It is surprising to me that no Oxygen showed up in the analysis (since there is no Oxygen peak). Had there been significant quantities of oxides (be they Al2O3 or TiO2) in the metal then we would seem them. Apparently any oxides are only there in negligible quantities, drowned out by the metallic Titanium and Aluminum.

The Carbon peak, although not unexpected from the presence of any surface contamination from handling, is fairly high. I must have found a dirty spot on the sample and not the spot I had cleaned before hand.

I will have other opportunities to use the EDAX, but I cannot do it too often, only when my other projects (ones which legitimately require the use of a scanning electron microscope) allow it. Next time I will make sure I clean the sample better.

blogfast25 - 15-10-2008 at 09:06

So, the high carbon reading could be explained away by sample contamination, until a better run can be made.

But the auspicious absence of O and N is also puzzling: you'd expect something made from an oxide and in the presence of air to be contaminated with both. I have some process descriptions for Vanadium that require pumping vacuum in the thermite reactor and backfilling with argon, to avoid all O and N. These, if I recall well, affect ductility of the metal...

Perhaps it would also be better to cut the nugget in half and polish one of the sides?

12AX7 - 15-10-2008 at 12:57

O, N, B, C and more, all negatively impact the characteristics of titanium. Which is why it's so hard to make good stuff, and which is why chlorides are usually used to make it.

It doesn't take much, on the order of parts per million, to affect the metal, but percents are barely detectable in the above method (what C is present shows up as a scant peak). So maybe the O and N content really is pretty low, as far as the measurement goes, but may actually be rather high as far as metal is concerned.

BTW, have you gotten around to smashing one of these nuggets? If they're so chock-full of stuff, they should be nice and brittle, something like chromium, and shatter into a million bits.

Tim

chloric1 - 15-10-2008 at 15:43

I have one chromium nugget about 1 cm and it is HARD. The metal from the thermite was brittle as shown by the smaller pieces. I wacked this nugget with a 20 ounce hammer and it rolled away in defiance. So the small particles cool quicker and the 'junk" gets trapped and good crystaline structure does not have a chance to form. The bigger ones stqay fluid long enough allow the "junk" to rise to the surface. Fluxing allows for bigger nuggets to form.

blogfast25 - 16-10-2008 at 05:38

Tim:

I would say the thermite titanium is decidedly brittle, yes. But I don't really have a point of comparison (I do have some high purity Ti but I'll be damned if I try and smash these samples up

).

Also, the thermite titanium contains some non-metallic acid insoluble residue, not exactly conducive to high quality metal, I guess... This may well be far more detrimental than any other impurity.

And ppm O and N wouldn't show up in Jeffrey's spectra, true. Not sure whether EDAX is suitable for such low level detection of these light elements?

Also, the choice of reducing TiCl4 with Mg has multiple motives, not just purity (but that plays an important part). A semi-continuous, relatively low temperature process with relatively cheap and plant-integrated recovery of the reductant by electrolysis of the by-product MgCl2, is always an attractive option. Chances are that even if the resulting metal would have required extensive refining (it doesn't), the Kroll process would still have found a way into the market...

[Edited on 16-10-2008 by blogfast25]

mrjeffy321 - 16-10-2008 at 10:04

I have not purposely tried to smash one of the Ti nuggets to pieces. However, during the polishing process, I do recall instances where some of the smaller nuggets would crack and break apart due to all the stress being placed on them by me pushing them into the grinding wheel so hard and the pressure of the pliers I was using to hold them. So they are somewhat brittle. They did, however, withstand the extraction process after the thermite reaction, which involves a lot of hammering to break off the Al2O3 slag surrounding the Ti metal.

No, EDAX is not suitable to determine the presence of elements in such low concentrations as parts per million. Theoretically, it could detect them, but their signals would get lost in the background noise (which is subtracted out at the end before quantification).

The_Davster - 30-10-2008 at 19:50

I am attaching an article on iron oxide/aluminum thermite
While the oxide is not remotely exotic, it is synthesized by sol-gel methods leading to combustion velocities on the order of >800m/s.

Hence why I believe this to count as exotic :cool:

Attachment: iron oxide thermite with very high velocity via sol-gel.pdf (1.4MB)
This file has been downloaded 1489 times

nitric - 2-12-2008 at 14:32

has anyone done a thermite reaction involving Mg instead of Al, i heard somewhere that there more heat and shock sensitive

12AX7 - 2-12-2008 at 18:43

If you had bothered to read the thread, you would already know the answer.

Nixie - 4-12-2008 at 00:40

Cough... Kettle. Pot.

blogfast25 - 9-12-2008 at 08:46

I haven't had the opportunity to work some more on the MnCl2 + Mg reaction but I did run the first tests on the aluminothermic reduction of niobium pentoxide, with interesting results so far.

About four 20 g reactions have been carried out with the base formulation (#1) being:

------------------------------------------------------------ mol
Nb2O5 ...................................................................... 1
KClO3 ................................................................... 0.05
Al ............................................................................. 3.4333...
CaF2 .................................................................... 0.42

Right from the off, niobium metal was obtained, but unfortunately the small chunks were locked into the alumina matrix and complete separation of metal and slag hadn't occurred.

Followed then some more attempts in which I increased firstly the flux level, then also the booster quantity (KClO3 to 0.1, then to 0.2 mol, adjusting also Al content of course).

The best result was obtained so far with KClO3 = 0.1, where neat, shiny pieces of niobium were obtained. But even there, metal/slag separation wasn't perfect.

Above a small lump of niobium metal (about 3 g), broken in two pieces. Externally, slag adheres very strongly to it. The metal is the typical 'silvery, gray' you find in so many descriptions of transition metals.

This thermite is unique in one respect from the many others I've successfully pulled off: the melting point of the metal (2,477 C) is actually higher than the melting point of the slag (2,054 C), so on post-reaction cooling it's the metal that solidifies out first, with the still molten slag 'dripping off' the metal. The amount of time the metal has to separate out is also quite small: in adiabatic conditions the expected end-temperature of the reaction is about 2,700 - 2,800 C, so on (natural) cooling the solidifying point of Nb will be reached quickly. I wonder also if solidifying micro droplets of niobium in the melt will not increase the apparent viscosity of the melt. The 'ideal' of a perfectly flat slag/metal puddle with all the metal neatly collected at the bottom of the crucible, may therefore be difficult to achieve in the case of the niobium thermite.

While chlorate heat-boosting is paramount to success, it hasn't got the overwhelming effect that it has in lower energy thermites (such as titanium) because the actual reduction reaction is already so energetic (ΔH = - 962 kJ/mol of pentoxide). The booster reaction has a ΔH = -1,255 kJ/mol of chlorate. As a result, theoretically the booster reaction increases the end-temperature of the mix only by about 55 C per 0.05 mol of KClO3 added.

As a consequence I believe that if too low end-temperature really is the problem here, a combination of preheating the mix and using chlorate heat-boosting is probably the solution. Larger size batches may also improve things, as they retain heat a little longer.

So the next attempt will be aimed at carrying out the reaction al forno.

[Edited on 9-12-2008 by blogfast25]

Titanium by Aluminothermy

franklyn - 16-12-2008 at 04:01

Titanium from Thermite.JPG - 456kB

blogfast25 - 16-12-2008 at 07:40

Well, well, someone has already found the printed issue of Popular Science here. The "Gert Meyer" referred to is me (although Theo misspelled my name slightly, it's actually Meyers).

Following a tip-off by 12AX7, who is also forum master at ABYMC (where I first reported calcium sulphate boosted TiO2

, Theodore Gray and me got in touch about him writing an article about homemade titanium. Months of waiting, guiding and much toing and froing later, Theo reproduced my results (described in great detail here) on a grander scale and took some awesome pictures. He wrote the article based on his experience. Apparently it made it to the cover, with photo!

Personally I hadn't seen the printed issue yet (being in Europe), but he's sending me one...

[Edited on 16-12-2008 by blogfast25]

franklyn - 16-12-2008 at 23:13

From a now deeply buried post 2 years ago , a very useful excerpt on techniques
for welding and repair of large broken structural and mechanical parts in the field ,
first published in 1910 , worth a look if you missed it the first time - http://ifile.it/o4pd7rm

.

Toxic site contamination

Paddywhacker - 29-3-2009 at 11:30

Mercuric oxide should be a vigorous oxidant in a thermite-type reaction. Only useful if you really wanted to contaminate a site, though.

PHILOU Zrealone - 31-3-2009 at 05:34

Quote: Originally posted by Paddywhacker

Mercuric oxide should be a vigorous oxidant in a thermite-type reaction. Only useful if you really wanted to contaminate a site, though.

It will also get much more explosive power owing to the vapourisation of Hg into gas...also the combination of oxygen and Hg into HgO molecule is very weak because a simple warming can free O2...so keep a safe distance from it, it must be handeled with due caution and only in tiny amount.
Initiation and power might be as fast and strong as flash powder!

[Edited on 31-3-2009 by PHILOU Zrealone]

[Edited on 31-3-2009 by PHILOU Zrealone]

grndpndr - 30-6-2009 at 10:21

Quote: Originally posted by PHILOU Zrealone

To be honnest...think a bit to what will happen if you blast a thermite mix?
It will spray all arround and take the reactants away from each other fast before they have had the time to react!
Even a fast exploding thermite won't exceed 500m/s while any low detonation is over 1,5km/s so better use only the Al/Zn/Mg powder in the explosive immediately because the other metal oxyde will be only dead weight-inert body!

PH Z

In the military an expedient flame device is a modified incendiary grenade using det cord/det and a squib to ignite the flare comp/thermate/detonator- det cord.The lethal/wounding radius
supposedly 35meters.Big difference between military thermate incediary device and a mechanically mixed thermite so FWIW fragmenting thermate devices are possible rigged correctly.

TM 9-1330-200

[Edited on 30-6-2009 by grndpndr]

[Edited on 30-6-2009 by grndpndr]

[Edited on 30-6-2009 by grndpndr]

ammonium isocyanate - 16-7-2009 at 18:27

I plan on using a few exotic thermite comps for my little brother's birthday. Here are a few possibilities I'm considering:

Al + Fe2O3 + CuSO4 (for color)
" + " + LiCl

Al + Fe2O3 + (NH4)2Cr2O7 + maybe something for color

Mg + (C2F4)

I'll post the results if they're interesting.

12AX7 - 16-7-2009 at 23:29

I doubt you'll get much color. Barium nitrate and magnalium (note: on topic: mixture is essentially a thermite intended specifically to yield barium oxide

) make an *almost* greenish burn, but it's much more overpoweringly white, from sheer blackbody radiation. Some chlorine in the mix would probably help greenify it, though. Maybe the same can be applied to thermite, in which case you'll need a chlorine source. The LiCl may work well for that reason.

Tim

ammonium isocyanate - 17-7-2009 at 09:49

My understanding was that chlorine deepens color. Is it specific to green? Becasue if so, the red/orange color of lithium flam would be counterproductive.

I might have just regular thermite surrounded by little piles of metal + oxidizer + color donor.

Or give the magnesium + teflon one a try. It creates alot of soot, so its used by the military for arial smoke screens. Could be cool, because the soot acts like a grey body. It might be hot enough to glow.

chloric1 - 18-7-2009 at 04:15

No chlorine is not specific to green. When LiCl is dissolve in methanol or in a pyromix, the flame is decidingly crimson. It has more to with the volatile species. Chlorides are more volatile than oxides and its these vapors that color the flames with excited states. All nitrates, carbonates, and sulfates are oxide yielding so there affects on flame color are weak.

ammonium isocyanate - 21-7-2009 at 15:57

Well, I finally got around to testing the LiCl thermite idea.

It was a little windy, and my lighter didn't work to well. I didn't want to waste reagents, so I crushed and mixed the following: 6.46 grams of MnO2, 3.03g of Al, and 1.15g of LiCl. I then stuck a magnesium ribbon in and tried to light it. No go.

So I added a couple match heads next to it to give a nice little intense flame. The ribbon still wouldn't light.

So then I added a little aluminium/NaNO3 mix to the top (around a gram or two). Still didn't light. :mad:

And then I added some aluminium/sulfur mix to the top (again, around a gram or two) Still didn't light!! :mad:

So I poured about a gram of magnesium powder on top. Finally it lit!

For a moment, all I could see was the Mg burning. Then the lithium color started to appear. After about a second of that, all color was just drowned out by an intense white light. So lithium chloride doesn't really have much affect, as it seems.

PHILOU Zrealone - 25-7-2009 at 23:28

LiCl is less good as LiOH...contrary to other salts where the chloride favors a rapid lower temperature ionisation of the cation, it is not Li(+) that induces the red color, but it is the sublimated LiOH (thus the entire molecule that provides the color).

Also:
Too high temperature mixes provide a color shift to the white side!
Pyrotechnic is an art to make mixes with the best appropriate burning temperature to allow the best color expression...it has taken centuries of research to achieve obscure mixes of given compositions...sometimes family secrets recipes

And to ammonium isocyanate:
NaNO3 will ruine the red color of LiOH...yellow Na(+) cation is the enemy of color for pyrotechnicians...better use a little KNO3...

[Edited on 26-7-2009 by PHILOU Zrealone]

12AX7 - 26-7-2009 at 00:46

FYI, a chloride added to thermite will melt and may shield the aluminum, requiring heavier ignition source. On the other hand, it will flux the reactants somewhat, and volatize once burning.

Tim

ammonium isocyanate - 26-7-2009 at 10:17

Well in my quest to find a reliable ignition source in windy conditions I have stumbled upon a very interesting mixture. It turns put that ammonium dichromate mixed thoroughly with magnesium powder provides an experemely bright flash when lit. It also covers anything within a foot with a layer of MgO. Unfortunately, becasue the explosion is so fast, it does not light thermite.

Regretably I did not measure out the weights, so I'm not exactly sure what the stochiometry of the reaction looks like. However, I tried it using aluminium powder (much cheaper), with 2.667 mols per mol (NH4)2Cr2O7 guessing at this stochiometry: 8Al + 3(NH4)2Cr2O7 -> 4Al2O3 + 3Cr2O3 + 2NH3 + H2. However, nothing happened except some normal decomposition of the ammonium dichromate

Noticed on eBay

Ritter - 21-1-2010 at 12:01

A CD-ROM with over 725 patent pdfs covering both THERMITE & powdered metal+inorganic oxidizer applications:

eBay item #360228321223

hissingnoise - 21-1-2010 at 12:06

Ritter, try searching Google Patents for thermite mixtures or similar. . .

Ritter - 21-1-2010 at 13:40

Quote: Originally posted by hissingnoise

Ritter, try searching Google Patents for thermite mixtures or similar. . .

Google Patents is very 'noisy' due to the OCR screening technology they used to convert the scanned patent documents into searchable data, which resulted in a lot of patents of poor print quality getting garbled in translation. It is very incomplete as a result & many things get missed when you search that database. It also covers only US patents. A lot of the early work by Goldschmidt & others were never patented in the US.

This CD has over 700 patents. Why reinvent the wheel?

[Edited on 22-1-2010 by Ritter]

chromium themit

The WiZard is In - 5-4-2010 at 17:51

Quote: Originally posted by PHILOU Zrealone

There was an extremely good post about thermites on alt.engr.explosive NG that was posted by Don Haarman 2 or 3 month ago!
You have a very long tale very instructive that explains all you want to know about all kinds of themites with various oxydes!

[snip]

-----------
I /dh/would add this from Popular Science 1935, on chrome thermit. Viewable via Google.com/books.

http://tinyurl.com/yhbqogo

And the "Home Chemist" Popular Science, September 1941. I cannot find this issue at Google.com/books.

franklyn - 3-5-2010 at 12:23

Can't think why The WiZard is In has posted this over there , if it properly belongs here.
http://www.sciencemadness.org/talk/viewthread.php?tid=13789

Survey of Combustible Metals, Thermites, and Intermetallics of Pyrotechnic Applications
- http://tinyurl.com/2f2bbj4

.

Ga Tech copper oxide thermite "explosion"

The WiZard is In - 4-6-2010 at 09:23

This I can believe.
---------------------------

Ga. Tech Students Hurt in Explosion at Frat House
Officials: Students mixed chemicals, causing blast
Updated: Wednesday, 02 Jun 2010, 6:50 PM EDT
Published : Wednesday, 02 Jun 2010, 4:46 AM EDT

By DARRYL CARVER/MYFOXATLANTA STAFF/myfoxatlanta
ATLANTA, Ga. - Two Georgia Tech students are in critical condition after fire
officials say they mixed chemicals that exploded.

Atlanta fire officials tell FOX 5 they were called to the Zeta Beta Tau fraternity house
at around midnight after reports of an explosion. When firefighters arrived, they found
two Tech students, who they said had been mixing chemicals outside on a patio on the
back side of the house. Georgia Tech officials say Tommy Keen of Peachtree City, an
aerospace engineering sophomore, and Paul Grzybowski of Appling, a materials science
junior, had been mixing chemicals that caused the explosion.

Officials said the chemicals the students mixed were aluminum powder and copper [oxide, either /djh/]
powder, creating a thermite explosion. Fire officials say about 15 people who were inside the house
at the time of the incident, but they had already evacuated by the time emergency crews arrived.

Georgia Tech released a statement Wednesday, saying "The Institute's Environmental Health
and Safety team is working closely with the Atlanta Fire Department to determine the exact
nature of the materials involved in this incident and how the injuries occurred. Georgia Tech's
primary concern is focused on the condition and well-being of the students involved in this
incident....While the extent of their injuries is unknown at this time, Georgia Tech will continue
to closely monitor their conditions."

The victims were transported to Grady Hospital for treatment of burns to their face, chest and hands.

Fire officials say the explosion appears to be accidental.

The incident is under investigation by the Atlanta Fire Department, Homeland Security and
authorities with Georgia Tech.

----
The original claim that they ignited their thermite with a butane tourch is not believable for
an iron oxide (any of the irons three oxides) thermite.

The dangers of fine copper oxide and aluminum powder are well know. Courser materials are
used to weld copper. Cadweld® being a commercial product.

The Cadweld MSDS's list both Cu2O and CuO.

http://www.erico.com/public/library/MSDS/LT1273.pdf
https://www.erico.com/public/library/MSDS/LT1298.pdf

Starting material — [I have seen a sparkler used.]

http://www.endeavorelectric.com/msds/MSDS-Cadweld%20Cadstart...

Mildronate - 17-6-2010 at 05:14

Here you can see may experiments with CuO + Al
http://www.youtube.com/watch?v=x6BjCxMVwUE
http://www.youtube.com/watch?v=kynAI0F8bfI

the Z man - 18-6-2010 at 14:09

I tried Mg fillings + PbO2 in a tiny quantity for fun. Not sure about the ratio, maybe 2 parts Mg + 1 part PbO2 by volume. It deflagrates in a very similar way to KNO3/Mg flash, maybe a little more violently, leaving a dark halo. No Pb found, probably vapourized.

I found a mix of PbO2/Mg/S/KNO3 (ratio something like 1/3/2/2 by volume) to deflagrate very violently, about one quarter gram going THUMP.

I'm thinking about copper peroxide. I found very little on this compound although it seem to exist, in strange compexes like CuO2*H2O2 ( http://www.springerlink.com/content/w675741vu4156421/). Maybe CuSO4+bleach or NaOH+H2O2? Seems too simple.

Now a strange thing maybe a little OT. When I used to play with KCLO3/Cu powder/S mixture (suicidal I know...) I mixed the copper powder ad sulfur first. Once I was mixing them very fast in a plastic beaker using a glass rod, when it caught fire! It was strange, it caught fire suddenly but not like a deflagration, it was like all the sulfer caught fire all at once not violently. It's weird that a Cu/S mix is friction sensitive, isn't it?

[Edited on 18-6-2010 by the Z man]

Anders Hoveland - 19-6-2010 at 19:36

I have tried magnesium powder with sulfur, and Mg powder with MnO2.
Adding sulfur to thermite seems to make it ignite a little easier, and increases the initial burn rate, but the smoke is very offensive in large quantities. The Mg with MnO2 made mushroom clouds that went up 20ft, even when only a few grams of thermite were used. The Mg thermite burns very fast, almost explosively, and there is a blinding white flash, even very bright in the daytime, but in daytime the torrents of smoke are even more visible.

[Edited on 20-6-2010 by Anders Hoveland]

Anders Hoveland - 22-6-2010 at 17:53

I had a thought to use CuMnO4 (cupric manganate) as the oxidizer with magnesium or magnalium (Mg-Al alloy common in pyrotechnics) powder. Mg-Al would actually be more explosive because, due to Mg reactivity, there is an effective limit to how fine of a powder is available. Smaller powder size is somewhat important, as if one uses bits of aluminum foil put through a cheese grater(not finely ground), it will not work for thermite.
CuMnO4 + 3Mg --> 3MgO + MnO + Cu

O/T - but..

argyrium - 23-6-2010 at 11:26

Quote: Originally posted by the Z man

SNIP...

Now a strange thing maybe a little OT. When I used to play with KCLO3/Cu powder/S mixture (suicidal I know...) I mixed the copper powder ad sulfur first. Once I was mixing them very fast in a plastic beaker using a glass rod, when it caught fire! It was strange, it caught fire suddenly but not like a deflagration, it was like all the sulfer caught fire all at once not violently. It's weird that a Cu/S mix is friction sensitive, isn't it?

[Edited on 18-6-2010 by the Z man]

Movement of the S in the plastic container very possibly generated enough static to ignite the suspended particles; probably not friction.

Microtek - 24-6-2010 at 04:34

Quote:

Smaller powder size is somewhat important, as if one uses bits of aluminum foil put through a cheese grater(not finely ground), it will not work for thermite.

Thermite works fine with very large grain sizes, it's just hard to ignite and burns slowly. For many applications this is preferable. I have made excellent thermite using un-shredded (ie. whole) aluminum foil, but it required a small regular thermite charge to ignite it.

Anders Hoveland - 24-6-2010 at 22:41

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

Skyjumper - 25-6-2010 at 13:59

Quote: Originally posted by the Z man

I tried Mg fillings + PbO2 in a tiny quantity for fun. Not sure about the ratio, maybe 2 parts Mg + 1 part PbO2 by volume. It deflagrates in a very similar way to KNO3/Mg flash, maybe a little more violently, leaving a dark halo. No Pb found, probably vapourized.

I found a mix of PbO2/Mg/S/KNO3 (ratio something like 1/3/2/2 by volume) to deflagrate very violently, about one quarter gram going THUMP.

I'm thinking about copper peroxide. I found very little on this compound although it seem to exist, in strange compexes like CuO2*H2O2 ( http://www.springerlink.com/content/w675741vu4156421/). Maybe CuSO4+bleach or NaOH+H2O2? Seems too simple.

Now a strange thing maybe a little OT. When I used to play with KCLO3/Cu powder/S mixture (suicidal I know...) I mixed the copper powder ad sulfur first. Once I was mixing them very fast in a plastic beaker using a glass rod, when it caught fire! It was strange, it caught fire suddenly but not like a deflagration, it was like all the sulfer caught fire all at once not violently. It's weird that a Cu/S mix is friction sensitive, isn't it?

[Edited on 18-6-2010 by the Z man]

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.

Anders Hoveland - 25-6-2010 at 22:54

I tried magnesium powder and epsom salt (MgSO4.7H2O). I tried in all different proportions. One would think this would be a violently reactive mix because burning magnesium explodes if water is added to it, but I failed to get this mixture to ignite and burn. I even put a mix of Mg and KClO4 above it and ignited it, but this still did not cause the bottom layer to burn. I think perhaps the hydrate absorbs much heat in giving off its water.

Perhaps using Ag2O2, which is not the peroxide, but the I,III oxide of silver, which is made from silver salts and H2O2 I think, it is on wikipedia. There is always Au2(MnO4)3 which can be made if you have the money to throw around. The synthesis involves gold, Cl2O7 and MnO2.

the Z man - 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'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.

pjig - 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?

Anders Hoveland - 26-6-2010 at 16:40

Ag2O2 + 4Cu --> 2Ag + 2Cu2O
3Ag2O2 + 4Fe --> 6Ag + 2Fe2O3
How is this for an unusual thermite reaction?

-=HeX=- - 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.

Anders Hoveland - 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!

-=HeX=- - 27-6-2010 at 16:16

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

spong - 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

)
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.

IndependentBoffin - 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!

The WiZard is In - 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/

That quick thermit's

The WiZard is In - 24-4-2011 at 15:59

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!

Neil - 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/

IndependentBoffin - 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]

The WiZard is In - 25-4-2011 at 08:33

Quote: Originally posted by Polverone

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.

Neil - 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?

hiperion42 - 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 1091 times

AndersHoveland - 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.

White Yeti - 16-8-2011 at 11:11

Aluminium and sulfur should give you one hell of a burn.

The WiZard is In - 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

White Yeti - 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.

AndersHoveland - 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.

Spart - 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]

Neil - 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.

Energetic Thermite s

blastron - 5-1-2012 at 05:38

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?

Neil - 5-1-2012 at 06:53

Read the whole thread and I promise you will find your answers.

AirCowPeaCock - 1-2-2012 at 12:15

2CrO3 + 3MgAl => Cr2O3 + 3MgO + 3AlO

then 3Cr2O3 + CrO3 => 5CrO2 + O2
O2 + MgAl => MgO + AlO
while
2Cr2O3 + 2Al + 3Mg => 4Cr + Al2O3 + 3MgO

by this time It has to be 1000s of degrees C, so..
5CrO2 + 4MgAl => 2Al2O3 + 4MgO + 5Cr

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

Bot0nist - 6-2-2012 at 08:09

Coming later this week.
Just put in an order for;

1lbs Mg powder -325 mesh
2lbs Atomized Al Spherical -400mesh
1lbs Atomized German dark Pyro Al 3-micron
1lbs Copper Oxide black
1lbs Iron Oxide red
1lbs Iron oxide black
2lbs Sulfur powder
2lbs Potassium Perchlorate (w/ cab-O-sil)

Looking forward to making some different thermites, maybe some "thermate", and flash compositions. I'm not sure if these reagents qualify as exotic, but do you all have any suggestions of what would be fun. Or what you would like to see. I will gladly post pics or small videos.

[Edited on 6-2-2012 by Bot0nist]

Bot0nist - 6-2-2012 at 22:32

Here are a few from Wikipedia that would love to try. I'll start with the basics first. I want to get a reliable "first fire" composition made so my thermites will be fuse sensitive. I hope that the fine size of the Al powder will help this. Maybe some Mg/Al/S + oxidizer if needed will get it going easy.

"There are many possible thermodynamically stable fuel-oxidizer combinations. Some of them are:

* Aluminium-molybdenum(VI) oxide
* Aluminium-copper(II) oxide
* Aluminium-iron(II,III) oxide
* Antimony-potassium permanganate
* Aluminium-potassium permanganate
* Aluminium-bismuth(III) oxide
* Aluminium-tungsten(VI) oxide hydrate
* Aluminium-fluoropolymer (typically Viton)
* Titanium-boron (burns to titanium diboride)

In military research, aluminium-molybdenum oxide, aluminium-Teflon and aluminium-copper(II) oxide have received considerable attention.[3] Other compositions tested were based on nanosized RDX and with thermoplastic elastomers. PTFE or other fluoropolymer can be used as a binder for the composition. Its reaction with the aluminium, similar to magnesium/teflon/viton thermite, adds energy to the reaction.[6] Of the listed compositions, that with potassium permanganate has the highest pressurization rate.[7]

Nanoparticles can be prepared by spray drying from a solution, or in case of insoluble oxides, spray pyrolysis of solutions of suitable precursors. The composite materials can be prepared by sol-gel techniques or by conventional wet-mixing and pressing.

Similar but not identical are nano-laminated pyrotechnic compositions, or energetic nanocomposites, in which fuel and oxidizer are deposited alternately in thin layers. The materials and the thickness of the layers control the detonating properties.[8] "

~ http://en.wikipedia.org/wiki/Metastable_intermolecular_compo...

[Edited on 7-2-2012 by Bot0nist]

Ral123 - 8-3-2012 at 14:30

I've just found that very cool thermite vid. http://www.youtube.com/watch?v=ZfGKP8W1ZE4&feature=relat...
Someone have an idea what composition they use? Can I make one with paper, thermite, barium nitrate and sulphur?

Vikascoder - 3-4-2012 at 09:36

Have anyone tried Potassium permanganate and calcium carbide thermite

virgilius1979 - 3-4-2012 at 10:03

Calcium carbide is pretty hard rock to crash and make powder and it would react with atmospheric moisture, so you need to use it fast.
I am curious about the reaction equation between these two subs.

Arcuritech - 21-8-2012 at 18:33

Quote: Originally posted by Vikascoder

Have anyone tried Potassium permanganate and calcium carbide thermite

CaC₂ and KMnO₄! That seems realy sensitive to me. I have, however, done C and KMnO₄, and that -while not a thermite in the traditional sense- burns extremely hot and with a brilliant white lilac flame. The little slag that survives is glowing a bright yellow immediately after the reaction and takes the form of a sponge. I'll post a video soon (hopefully).

Eddygp - 23-9-2012 at 11:30

^ Wow, Calcium carbide and potassium permanganate must be awesome!

elementcollector1 - 29-9-2012 at 13:39

Just tried igniting a MnO2 thermite, without good results. The powders of MnO2 and Al were mixed together in no particular ratio (much more Al than Mn by volume), and a pile of permanganate was placed on top with a magnesium ribbon in the middle. Upon addition of glycerin, the pile smoked but did not ignite. I tried adding a little more permanganate, then a little more glycerin a couple times, until parts of it ignited, but I never had the whole thing ignite. Why is this? Did any of the thermite actually ignite, or was it just the glycerin?

triplepoint - 29-9-2012 at 16:33

Quote: Originally posted by elementcollector1

Just tried igniting a MnO2 thermite, without good results.

How clean was your MnO₂?

hyfalcon - 30-9-2012 at 01:52

Try a common sparkler for your ignition. If it's gonna burn, that will set it off.

Another thought if to try the sulfur/aluminum prime talked about further up in the thread.

[Edited on 30-9-2012 by hyfalcon]

Dr.Bob - 30-9-2012 at 17:04

I seem to remember that the Aluminium-bismuth(III) oxide is used in Dragon egg fireworks to generate the loud boom/crackle, due to the fact that the bismuth boils at the temperature of the reaction, so it tends to explode noisily rather than burn. So be careful with that one. Same goes for lead based thermites. I have only done a few, but they are easy to make too large or violent. I actually had a teacher once run one for a demo that got pretty large and out of control. It was a lot of fun...

elementcollector1 - 17-10-2012 at 15:52

MnO2 was black, and very pure, may not have been dehydrated enough.
Don't have any sparklers, but that S and Al idea might be good.
Another thought is to drip a small amount of molten Al onto the thermite mix. If that can't ignite it, then... might have to flip some tables.

PHILOU Zrealone - 22-10-2012 at 08:39

Quote: Originally posted by Spart

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]

If you want to get Cu powder out of Al powder...maybe try to let fine Al powder fall into a blue concentrated solution of CuSO4 with a few ml of HCl as catalyst.
The HCl will help to depassivate the oxyd layer of the Al powder...then naked Al will react with Cu(2+)...to produce copper metal powder.
2Al + 3Cu(2+) --> 2Al(3+) + 3 Cu

In brief, the blue solution will fade to an uncolorized one... CuSO4 will disappear and form Al2(SO4)3
Copper powder will remain at the bottom.

Slags

j paul - 15-11-2012 at 14:23

could I ask if people who have the opportunity, would please look at old slags that have been left exposed to the weather.

In particular:

TiO2 - Al burns,TiO2 is easily soluble in molten alumina, but only slightly soluble in solid alumina. This leads to the TiO2 exolving out of the solid alumina to form microscopic Rutile crystals, leading to a phenomenon known as asterisim. These star stones, if they are of a reasonable colour, can be polished as trinkets.

Ca rich burns should produce a slag that left exposed to the CO2 and water vapour in the air, should break down to chalk and ( ? ).

a Mg/Al alloy fuelled burn will provide the ingredients for making spinel MgAl2O4 the question is can these form crystals in a matter of years / decades?

Please don’t get the idea that I think that if you look at your old slags you will find gem stones. You will not. What you might find are small dark mineral specimens that are so full of crystal defects as to be useless. I could be wrong about that, you might fined perfect crystals of Diaspore, but I doubt it. please go and look if you can, if you are new to thermites just give a couple of seconds thought to what else you are making when you make that blob of metal.

Further up this thread Blogfast describes a very interesting failed attempt to use lime as a fluxing agent for reducing Silicon. Before I read that post I was going to suggest silica and lime as a combination to form a slag with alumina, as a possible way taking some of the heat out of the Manganese reduction whilst having a very liquid slag. Both Anorthite CaAl2Si2O8 and Grossular Ca3Al2(SiO4)3 are described as fusible in mineralogy text books, this means that they can be melted in the flame of a spirit lamp. So what happened. I suspect that the Fluorine from the fluorite reacted with the alumina and the surface of the silica grains, to coat them in a layer of Al2F2SiO4 Topaz. Assuming that this is the case then fluorine should be kept away from alumina-silicate melts. And for that bit of information Blogfast should be thanked.

SM2 - 16-11-2012 at 06:46

one day I was trying to make sodium JFTFOI, cutting corners, so I wrapped some Lye in a long sheet of Heavy Duty Reynolds, and twisted at both ends to make a nice, tight Al foil turd. Scene 2: thrown into red hot oak fire. Definitely an exothermic reaction going on there. Analogous (but more controlled) ways of making alkali earths could, I suppose, be construed as a type of thermite. I'd have to try with powdered Al and powdered K0H. SUPER DRY, as in grignard dry.

BTW: sparkler better than Mg ribbon?

[Edited on 16-11-2012 by Fennel Ass Ih Tone]

SM2 - 16-11-2012 at 06:52

Quote: Originally posted by elementcollector1

Just tried igniting a MnO2 thermite, without good results. The powders of MnO2 and Al were mixed together in no particular ratio (much more Al than Mn by volume), and a pile of permanganate was placed on top with a magnesium ribbon in the middle. Upon addition of glycerin, the pile smoked but did not ignite. I tried adding a little more permanganate, then a little more glycerin a couple times, until parts of it ignited, but I never had the whole thing ignite. Why is this? Did any of the thermite actually ignite, or was it just the glycerin?

A sure-fire (n pun I) way is by adding ethylene glycol antifreeze (best brand is Dog Killah) to some HTH. Works every time. Lots of white smoke, followed by a very hot fire.

Metacelsus - 1-1-2013 at 16:12

Quote: Originally posted by elementcollector1

The KMnO4 also needs to be finely powdered to ignite the glycerin. Otherwise, it just smokes.

franklyn - 15-1-2013 at 22:15

A universe of Thermites are listed in the appendices
Survey of Combustible Metals , Thermites , & Intermetallics for Pyrotechnic Applications
www.dtic.mil/dtic/tr/fulltext/u2/a419762.pdf

.

Tdep - 11-2-2013 at 04:18

I was thinking about doing a thermite with tungsten trioxide, made from sodium tungstate which in turn is from 100% tungsten TIG rods (don't want no thorium).

What am I expecting? I'm assuming quite violent because of tungsten's low reactivity but will the thermite get hot enough to melt the tungsten metal? Does the metal need to melt for the reaction to procede?

I know i'm going from tungsten to tungsten but SCIENCE!

jpsmith123 - 5-5-2013 at 14:27

While I was looking for papers on the combustion synthesis of Bi2O3, I came across an interesting paper which implies that Al/Bi2O3 (using nanopowders) might make a good detonator. The paper's attached.

Attachment: nanoenergetic_gas-generators_principles_and_applications.pdf (375kB)
This file has been downloaded 832 times

malford - 26-6-2013 at 20:02

Quote: Originally posted by jpsmith123

While I was looking for papers on the combustion synthesis of Bi2O3, I came across an interesting paper which implies that Al/Bi2O3 (using nanopowders) might make a good detonator. The paper's attached.

I just posted about this paper also in another section. I'm hoping to get some others to go in with me on a group buy of nano Al powder and possibly Bi2O3 form us-nano.com

[Edited on 27-6-2013 by malford]

A Fresh Lunatic - 24-10-2013 at 02:30

I make brass parts on a minilathe, and have a large tub of fine milled brass, which I know is 20% zinc. What would be a good oxide to mix this with for a thermite reaction ? Presumably, copper oxide wont work ?

bismuthate - 24-10-2013 at 03:30

Not much would work as copper is very unreacive. You cold try a noble metal oxide, but that's exbensive.
I want to do a lithium and silver oxide thermite. I also wonder about using mercury oxide with aluminum or another metal as a thermite.... or CuO/Hg
(I'm just speculating I don't actually plan to use mercury.

A Fresh Lunatic - 24-10-2013 at 16:01

SO, how can we determine if Mercuric Oxide would have a thermic reaction with copper metal , other than trying it? presum,ably, the end products woudl be mercury metal and cupric oxide ?

Fenir - 24-10-2013 at 16:20

By adding a drop of water to a potassium permangenate and glycerin slurry, one can speed up the reaction time immensely. This is quite helpful when igniting thermite mixes.

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