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chloric1
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[*] posted on 23-7-2008 at 23:12


Blogfast-read some of your blogs and I noticed you have done alloy thermites. Have you tried ferromanganese? The red iron oxide is probably more tame and the resulting iron could absorb the manganese. This would be a neat way to produce ferromanganese anodes for electrolytic permanganate production.



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[*] posted on 24-7-2008 at 03:56


No, I haven't but that would work without a question of doubt, for just about any Fe/Mn ratio desired. Since as both the Fe2O3 and the higher oxides of manganese produce such energetic thermites, it might be recommendable to use Mn2O3 or even MnO when co-reducing with iron oxide, to keep the heat generated to a manageable level and prevent too much Mn from evaporating off...

I did once run a mixed Cu2O/MnO2/SiO2 thermite, aiming at an alloy of 70 w% Cu/15 w% Mn and 15 w% of Si. Analysing the resulting bronze I found back these proportions more or less.

[Edited on 24-7-2008 by blogfast25]
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[*] posted on 24-7-2008 at 12:41


Quote:
Originally posted by blogfast25I did once run a mixed Cu2O/MnO2/SiO2 thermite, aiming at an alloy of 70 w% Cu/15 w% Mn and 15 w% of Si. Analysing the resulting bronze I found back these proportions more or less.


I've been wondering if I could blend some Cr2O3 with Fe3O4 and get a polishable "stainless steel". Anybody tried it?
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[*] posted on 24-7-2008 at 17:25


Why? If you are going to spend chemicals, make something not found at your hardware store. Like ferromanganese anodes, silicon bronze, titanium bronze etc.



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[*] posted on 25-7-2008 at 05:11


Quote:
Originally posted by chloric1
Why? If you are going to spend chemicals, make something not found at your hardware store. Like ferromanganese anodes, silicon bronze, titanium bronze etc.


You know, it's never occurred to me to ask my hardware store for WHITE-HOT BOILING stainless steel. I'll ring them right up and ask. :)

I'm not trying to develop a production process, just an interesting demonstration. Shopping at the hardware store can be interesting, of course, but not in the same way.
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[*] posted on 25-7-2008 at 05:12


Quote:

I've been wondering if I could blend some Cr2O3 with Fe3O4 and get a polishable "stainless steel". Anybody tried it?


As far as my experience shows (and theory predicts) mixed thermites are no problem. This is certainly true if both individual thermites yield the reaction products in molten form. I've done FeSi, FeCr, FeV, FeTi, CuTi and a few other exotic ones. These can be used as masteralloys, to dope any other steel (or Fe based alloy) with small amounts of these metals.

In the case of FeSi and FeTi the formulations have to be designed bearing in mind that the Ti and Si thermites are hardly exothermic at all and that most heat will have to come from the Fe2O3 (or Fe3O4) reduction. Aiming too high in Si or Ti would lead to the slag being obtained in solid or "slushy" form, the alloy will then not be able to mix and separate out form the liquid reaction products.

Masteralloys comprised of more than two components are also perfectly possible. There are quite a few thermite based patents pertaining to quite complicated mixtures, including those containing Mo, Mn, W, Co, Cr, Nb and other (high MP) transition metals...
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[*] posted on 26-7-2008 at 03:57


Quote:
Originally posted by -jeffB
You know, it's never occurred to me to ask my hardware store for WHITE-HOT BOILING stainless steel. I'll ring them right up and ask. :)


LMAO:D:D

You put it like that, after leaving my neighborhood hardware store with my white hot stainless, I'll head off to the local pub and have myself a molotov cocktail.




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[*] posted on 31-7-2008 at 06:50
Cr2O3 + Mg


I recently tried a small batch of Cr2O3 + Mg thermite.

I ignited it using United Nuclear's "Thermite Ignition Mix", which I have a can of laying around. The results were a brilliant 2 foot fountain of sparks that was a very bright yellow color. No residue other than some un-reacted mix was left behind. The rest seems to have gone up in a cloud of white ash.

The issue is that when I made this mix it was in a place where I did not have a scale so the ratios were guessed, I think it may have been a bit Magnesium rich which may have contributed to the reaction speed.

Sorry, no pics it was too fast.

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[Edited on 31-7-2008 by ssdd]




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[*] posted on 31-7-2008 at 13:08


Ouch! Would be nice to have a regulas of chromium:(:(

Actually, I am sticking to using aluminum here and I wanted to use potassium dichromate as a booster. I have both 300 mesh and 400 mesh Al, so I think 15% dichromate is all that should be needed. I worked out the dichromate reduction in thiis equation:

K2Cr2O7 + 2Al >2KAlO2 + Cr2O3
Cr2O3 +2Al > 2Cr +Al2O3
NET: K2Cr2O7 + 4Al >2KAlO2 +2Cr +2Al2O3

Yep, that seems right.




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[*] posted on 2-8-2008 at 08:38


I came upon a patent to the U.K. MoD for a thermite-like incendiary formulation here http://www.pat2pdf.org/patents/pat3954530.pdf.

They use soluble Pb(II) salts (either acetate or nitrate) in water solution mixed with powdered boron to create intimate mixtures that can be ignited when dry. Here is my guess at the processes involved:

2Pb(NO3)2 > 2PbO + 4NO2 + O2

This reaction takes place in hot aqueous NaOH. No mention is made of the gas production.

And the thermite-like reaction:

3PbO + 2B > B2O3 + 3Pb

Here is Example I via an OCR scan of the patent pdf:

Quote:
EXAMPLE 1

6.0g. of amorphous boron (around 1.0 micron particle size) are suspended.in 1.2 liters of aqueous sodium hydroxide solution containing 0.32 mole sodium hydroxide. The suspension is stirred and heated to 90°C.

1.06 liters of lead nitrate solution containing 0.8 mole
lead nitrate and 1.06 liter of sodium hydroxide solution
containing 1.60 moles sodium hydroxide are added to
the stirred suspension simultaneously and dropwise
during 42 minutes, the temperature being maintained
at 90°C during the precipitation. A further 15 minutes
stirring after addition is given, the precipitated product
settles quickly when the stirring is discontinued and the
supernatant liquor is decanted hot. The boron is com
pletely incorporated in the lead oxide orthorhombic
crystals and the supernatant liquor is clear and free
from elemental boron. The product is washed twice in
the precipitating pan by decantation.

The product is transferred on to cambric cloth on a Buchner funnel, sucked free of excess water, washed with methylated sprits and dried by passage of dry air
or on a hot table at 60°C. The yield obtained is 180g. The product has a low bulk density of 0.4 g/mI and contains about 3 percent boron by weight. In appearance it ressembles aluminium flake and it readily burns when ignited in an open train.



FYI, PbO & the Pb(II) salts are toxic. Other than that, this looks like a workable procedure for a home lab.

A related boron-fueled thermite-like system is used in a pyrotechnic formulation in http://www.pat2pdf.org/patents/pat4853052.pdf to the Swedish arms firm Bofors. In their formulations they use the following mixtures:

Boron
Zirconium, titanium or nickel/zinc alloy
PbO2
SnO2
TiO2
Bi2O3


[Edited on 2-8-2008 by Ritter]




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[*] posted on 2-8-2008 at 11:58


Quote:
Originally posted by chloric1
Ouch! Would be nice to have a regulas of chromium:(:(

Actually, I am sticking to using aluminum here and I wanted to use potassium dichromate as a booster. I have both 300 mesh and 400 mesh Al, so I think 15% dichromate is all that should be needed. I worked out the dichromate reduction in thiis equation:

K2Cr2O7 + 2Al >2KAlO2 + Cr2O3
Cr2O3 +2Al > 2Cr +Al2O3
NET: K2Cr2O7 + 4Al >2KAlO2 +2Cr +2Al2O3

Yep, that seems right.


With dichromate alone this is likely to be near-explosive. Small amounts of dichromate could be used to increase reaction temperature.

Personally for Chromium I prefer the classic KClO3 + 2 Al ---> KCl + Al2O3 as a booster system for Cr2O3 + 2Al ---> 2 Cr + Al2O3

I have a recipe (with KClO3 and 400 mesh Al) that gives good Chromium reguli, if you're interested...
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[*] posted on 2-8-2008 at 16:02


Quote:
Originally posted by blogfast25


Personally for Chromium I prefer the classic KClO3 + 2 Al ---> KCl + Al2O3 as a booster system for Cr2O3 + 2Al ---> 2 Cr + Al2O3

I have a recipe (with KClO3 and 400 mesh Al) that gives good Chromium reguli, if you're interested...


Well, in that case I am interested in your formula. I wish to try both and do a comparison. If I have time tonight I want to try a thermite based on this formula:

Chromium Oxide 240 grams
Aluminum 300 mesh 99 grams
Potassium Dichromate 36 grams

I believe this what I am after. After you give me your formula then I can try some other time and compare both.

BTW I know thermite usually burns 2400 to 2500 degrees C. What about aluminum with STRONG oxiders like dichromate,perchlorate, permanganate etc? Possibly 3000 degrees?

[Edited on 8/2/2008 by chloric1]




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[*] posted on 2-8-2008 at 16:56


Quote:
Originally posted by chloric1
BTW I know thermite usually burns 2400 to 2500 degrees C. What about aluminum with STRONG oxiders like dichromate,perchlorate, permanganate etc? Possibly 3000 degrees?

[Edited on 8/2/2008 by chloric1]


Explosion.

(Permanganate and Al is flash powder.)

Small amounts added as a booster will likely increase burn rate and ease of ignition.

[Edited on 8-2-2008 by ShadowWarrior4444]




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[*] posted on 3-8-2008 at 05:28


Chloric1:

Firstly, the end-temperature to which a thermite reaction runs depends on various factors, the thermochemistry itself being a prime factor. Thermites based on TiO2, SiO2 and some other very, very stable oxides either don't burn at all or burn slowly and not very hot. This is certainly also true of a few Period 5 and Period 6 transition metals, where reduction of halides is usually preferred.

The Gibbs Free Energy released during the reaction (ΔG = ΔH - TΔS) indicates whether the reaction can take place or not and the reaction enthalpy (heat) ΔH, together with how much reaction products are formed, their heat capacities and heats of fusion (if applicable), as well as to what extent the reaction vessel is thermally insulated from the rest of the world, determines the end-temperature precisely and unequivocally.

Regards the Chromium thermite, remember that to obtain good quality metal reguli, usually fluorite is needed to obtain good metal/slag separation (but it isn't always indispensable). Most of my thermites, designed to produce good quality metal, contain fluorite (CaF<sub>2</sub>;). Here's my Cr formula (this is a stoichiometrically balanced mix):

in mol: Cr<sub>2</sub>O<sub>3</sub> = 1 mol; Al = 2.82 mol; KClO<sub>3</sub> = 0.41 mol, CaF<sub>2</sub> = 0.6345 mol

in gram: Cr<sub>2</sub>O<sub>3</sub> = 152 g; Al = 75.8 g; KClO<sub>3</sub> = 50.2 g, CaF<sub>2</sub> = 49.5 g

The fluorite level could be reduced or it could be eliminated altogether but bear in mind that fluorite is a slag fluidiser as well as a heat sink: without fluorite the reaction will run hotter (and that's not necessarily an advantage, if metal production and not pyrotechnics is your goal).

Let me know how you get on... :cool:

[Edit]

Also, the reaction between K2Cr2O7 and Al is likely to run to elemental K, not KAlO2, because K2O + 2/3 Al ---> 2 K + 1/3 Al2O3 is exothermic by -195 kJ/mol of K2O.

The overall booster reactions can then be balanced as:

K2Cr2O7 ---> K2O + 2 CrO3
K2O + 2/3 Al ---> 2 K + 1/3 Al2O3
2 { CrO3 +2 Al ---> Cr + Al2O3 }

K2Cr2O7 + 14/3 Al ---> 2 Cr + 2 K + 7/3 Al2O3

The third part is the one likely to produce enormous amounts of heat.

If you want to use 240 g (1.58 mol) of Cr2O3 and 36 g (0.122 mol) of K2Cr2O7, the amount of Al should then be increased slightly to about 107.4 g to respect stoichiometry.

The level of heat booster in your dichromate boosted formulation is quite low: 0.077 mol of K2Cr2O7 per mol of Cr2O3. For my chlorate based formulation it is 0.41 mol of chlorate per mol of Cr2O3.

But since as I have no thermochemistry data for K2Cr2O7 or Cr (+VI) oxide at hand, it's difficult to say whether the chromate boost will be enough to obtain molten slag and metal. The advantage of using dichromate is of course that it also produces Cr and not just alumina and KCl. I think it's the safest way for now to test the low level of dichromate first.

[Edited on 3-8-2008 by blogfast25]
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[*] posted on 3-8-2008 at 17:27


Thanks blogfast! I appreciate that and I am taking notes. I got the dichromate idea from a couple of older digitized inorganic chemistry books. One uses Chromium trioxide and the more modern one uses potassium dichromate! The hexavalent chrome makes up significant portions simular to your chlorate formula but they are using 30 mesh Al!! So I toned it down to accommodate for finer powders.

OUCH! I did not factor in the fact Potassium metal is formed. Certain that it will be a purple vapor flame!:o:o
I really need to get a grasp of theorical thermochemistry. I am planning on studying in the University soon.

I do not have fluorspar at this moment but plan to get some. For this, and the fact I have spent the weekend entertaining guest I have yet to do my trial. I will let you know when I get around to it(possibly Monday or Tuesday evening). My next big order will include some fluxes so I can
compare the run with/without flux.

I would think slightly less fluorspar could be used because the potassium vapor should lower temperature somewhat but how much I don't know.

[Edited on 8/3/2008 by chloric1]




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[*] posted on 4-8-2008 at 08:27


Chloric1:

Thermochemistry of thermites (and assorted reactions) isn't very complicated at all: it requires only basic algebra and invoking a couple of laws.

Here's an example of a thermochemical calculation for a boosted TiO2 thermite (the post is mine)

Another one on ferrotitanium, as well as a general calculation of the estimated end-temperature for a generic thermite (the post is mine too)

The cooling effect of the potassium will be small but could be accurately estimated using the heat capacities (Cp,l and Cp,s), heat of fusion and heat of evaporation of K. In your proposed formulation the cooling effect is likely to be negligible because the amount of K formed is small.

But in the KClO3 boosted formulation, where 0.41 mol of KCl are formed, heated, fused and evaporated (following Hess), the cooling effect has to be taken into account even though compared to the heat generated by KClO3 + 2 Al ---> KCl + Al2O3 is enormous. It all depends how accurate you want the calculation to, of course... :)

[Edited on 4-8-2008 by blogfast25]

[Edited on 4-8-2008 by blogfast25]

[Edited on 4-8-2008 by blogfast25]
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[*] posted on 4-8-2008 at 15:06


Well the more I thought about superheated potassium vapor, the more I realized how little of an effect it will have. Not only that but I am considering the chemistry here. You will have molten Aluminum Oxide not to mention heated air surrounding reaction. So any losses of potassium would result in immediate combustion releasing white clouds of potassium oxide(don't breath;)),or immediate combination of said oxide with the molten alumina hence my original deduction of potassium aluminate as a product intermixed in a matrix of the alumina slag. I appreciate the post on thermochemistry of thermites. With your permission, I would like to copy them and save them as a Word doc.



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[*] posted on 5-8-2008 at 03:23


Chloric1:

Feel free to copy.

I'm quite interested in testing K2Cr2O7 (I have some) in a Cr2O3 formulation myself. The dichromate should be incredibly powerful, because of its oxygen (molar) content (7 mol O per mol), slightly higher than twice the molar oxygen content of chlorate (3 mol O per mol). Very roughly speaking it will generate about twice the amount of energy of potassium chlorate (compared on a mol to mol basis). That's why it's definitely recommendable to start with low quantities: it should be very, very energetic.

[Edit]

I've just estimated the dichromate booster reaction K2Cr2O7 + 14/3 Al ---> 2 Cr + 2 K + 7/3 Al2O3 to have a reaction enthalpy of about - 2800 kJ/mol of K2Cr2O7, more than twice the value of - 1255 kJ/mol of KClO3 (for KClO3 + 2 Al ---> KCl + Al2O3).

That is a phenomenally high value for a booster system. A formulation with 0.15 to 0.2 mol of K2Cr2O7 per mol of Cr2O3 will almost certainly give liquid Al2O3 and liquid Cr. That level of booster will yield an extra 420 to 560 kJ, to supplement the heat coming from the Cr2O3 reduction.

But for now, for safety reasons, I'd stick to your proposed lower level. Crank it up gradually, if need be...

[Edited on 5-8-2008 by blogfast25]

[Edited on 5-8-2008 by blogfast25]
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[*] posted on 5-8-2008 at 15:07


Well, it definately ignited I will post a link to video when I get a chance to upload it. I use a flower pot half fill with sand. Truthfully, I was worried the pot would fly apart but it just made a "ping" when after the permanganate/glycerol hypergolic subsided and the thermite ignited. I really am getting tired of this ignition system because the smoke obscures my view and it smells like burnt sugar. Anyhow on to the mix. It gave off green smoke:o Obviously some chrome oxide was mechanically lifted by the vigor of the reaction. The slag/mess looks porous so I am not too optimistic. I will break her open around 9 PM GMT-5 to look for metal.

Since I prepared like 383 grams of thermite I still have 70-80% left:cool: so we can optimize together then compare to chlorate bosster and I will order fluorspar this week.


Update: Just uploaded my videohere

I did not find a distinctive globule or regulas. More like a broccoli sprout:( It is very hard but very brittle. I think it is chromium in a alumina matrix. I also seen some unreacted chrome oxide so I think it was not hot enough. I will post more findings later.



[Edited on 8/5/2008 by chloric1]




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[*] posted on 5-8-2008 at 22:51


You're very close to success. I can tell just by looking at the vid that the whole thing is running just a little too cool. Increase the dichromate/Al slightly (stoichiometrically).

For ignition I use a small amount of KClO3/Al (stoichiom.) mix, about 1 ml, lit with a piece of magnesium ribbon. Alternatively, light the chlorate with a pen sized blow torch. KClO3/Al burns incredibly hot, yet is very safe: it isn't a flashpowder at all.

The slag is made up mainly of fused alumina (and that IS HARD!) and powdered chromium, a kind of cermet. CaF2 will help the alumina/Cr flow to the bottom of the crucible before it solidifies on cooling.
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[*] posted on 6-8-2008 at 02:11


Well I have magnesium ribbon coming this wek I hope. I ordered 225 feet! I plan on selling most of it to finance research:cool: Next I do this I will measure out a 100 gram charge. I will figure out the dichromate addition based on your numbers of .15 tp .2 moles. Today I have to decide who to order fluorspar from. Not all pottery suppliers are created equal. I also need to order black iron oxide and possibly something else. This all helps to justify the shipping costs.



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[*] posted on 6-8-2008 at 07:17


Why not get some vanadium pentoxide (pottery grade)? That's a real nice thermite, very hot and nice metal too. Cobalt's nice too, from CoO... The one I'm most interested in is niobium pentoxide: no boost needed, burns straight to about 2740 K! But I can't get any Nb2O5 here... :(

Instead of CaF2, cryolite (Na3AlF6) should also do the trick but it's more expensive of course.

I'll probably be moving away from oxides and move to halides (mostly chlorides). I've a MnCl2 + Mg ---> Mn + MgCl2 on the drawing board.
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[*] posted on 6-8-2008 at 13:16


Thats just it, I got numerous suppliers for CaF2 and cryolite but I need the supplier with reasonably priced vanadium pentoxide. So I can thermite it and sell some too. I have one supplier that wants $45 per pound!! I have a couple others that range $13-15 per pound! There is definately no set standard on these type of item hence money can easily be made. The niobium pentoxide will probably have to be purchased directly from China or India in 25Kg quantities or more. I am definately unable to swing that as of now:(

Why do you want to move away from oxides? Want a new challenge? The problem with halides is that many are VERY soluble and hydroscopic. Many Fluorides are insoluble and would be easy to obtain anhydrous.

Personally, I wanted to make up some lead bromide and make a thermite with that and try to catch the aluminum bromide smoke in a bell jar or?:o

[Edited on 8/6/2008 by chloric1]




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[*] posted on 7-8-2008 at 01:16


Yes, a new challenge. Most chlorides are indeed hygroscopic but drying them is usually possible. Anhydrous fluorides are hard to make: usually hydrofluoric acid or anhydrous HF and in some cases fluorine is needed. They're also much more expensive and more restricted for sale to private individuals (at least in Europe).

High grade Nb2O5 is available from ChemSavers but needless to say only at ridiculous prices.

The reduction PbBr<sub>2</sub> + 2/3 Al ---> Pb + 2/3 AlBr<sub>3</sub> is only just barely exothermic: ΔH = - 64 kJ/mol of PbBr2 (at 298 K) (for chlorides and bromides, Mg is much preferred to Al but for fluorides Al also works. This is mainly because of the fact that in the series of AlX3, AlF3 has by far the highest heat of formation).

I'm not sure (but it can be calculated) whether the temperature would be high enough to evaporate the AlBr3 and in any case it would be heavily contaminated with lead, due to mechanical entrainment of the nascent lead. AlBr3 must also be very prone to hydrolysis. Like for AlCl3, reaction of Al with dry HBr in a glass labware set up with condenser is to be much preferred here.

I just took receipt of my Mg powder, so the MnCl2 reduction project can now go ahead. :)
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[*] posted on 7-8-2008 at 15:03


Well, I had to order cryolite because the supplier was out of fluorspar. I also ordered nickel and black iron oxides to justify shipping. I ordered the vanadium pentoxide from another supplier at hopefully a low price along with red copper oxide. They will confirm with me later.

Good luck with your manganese chloride project. You wouldn't have the thermal date for cryolite would you? Have not had been able to visit NIST yet.




In the theater of life its nice to know where the exit doors are located.
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