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Author: Subject: Detonation of erythritol tetranitrate (ETN) with heated aluminum
Melgar
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[*] posted on 16-3-2010 at 15:24


I used ammonia to neutralize for several reasons. First, it's not really that strong of a base, at least compared to more typical bases like NaOH. Second, if you put in too much, it doesn't matter since it will just evaporate when you dry it. Third, after neutralization, drying the water gives ammonium sulfate and ammonium nitrate, both of which I can use. Fourth, the first time I did this I used baking soda and miscalculated how high up the foam would go a couple times and had it erupt all over my workbench. Fifth, I read about industrial nitration where it's neutralized with ammonia. And sixth, I have a one-gallon jug of 28% ammonia. :D

I did a set of slightly more controlled experiments and learned two things. First, aluminum does indeed produce a more powerful reaction than glass and other metals, though other materials can produce various strengths of detonation if the ETN is heated fast enough. And of course, the other thing I learned was that the detonation strength is also strongly dependent on how fast it's heated.

When heated on glass, ETN will gradually decompose into smoke. When heated on steel, ETN will actually undergo a sort of very weak detonation, where it all disappears at once but doesn't make much noise or create much force. Aluminum will give a strong detonation when heated on foil, but when heated on a section of an aluminum bar, it slowly decomposes at first, but then does the same thing as steel.

Nichrome wire wrapped in aluminum foil can also do a pretty good job of detonating ETN, as long as it gets hot quick.

I don't think there's any NH4NO3 in my ETN in significant amounts. At least not the recrystalized batch anyway. The recrystallized stuff does seem like it doesn't detonate quite as well, but now I'm starting to think that's because I use less of it because it's composed of flat, fluffy crystals. The stuff that wasn't recrystallized is in good-sized chunks, which make it easy to use more. And I don't have a scale that can measure the size weights of the ETN I'm willing to set off. So far it's all been really tiny amounts that wouldn't register on the scale.
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per.y.ohlin
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[*] posted on 16-3-2010 at 15:45


Detonation refers to a supersonic explosion. If the ETN goes "poof", it is called a deflagration. If the ETN goes "bang", and makes your ears ring, it is most likely a detonation.
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hissingnoise
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[*] posted on 17-3-2010 at 06:49


Black powder, when confined, will go 'bang' and make your ears ring but black powder doesn't detonate. . .




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Melgar
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[*] posted on 17-3-2010 at 07:45


Quote: Originally posted by hissingnoise  
Black powder, when confined, will go 'bang' and make your ears ring but black powder doesn't detonate. . .

True, but he was referring specifically to ETN.

I only called it "detonation" to distinguish from "burning", which is the same thing as deflagration, and didn't accurately describe what it was doing. ETN definitely detonates when heated quickly on aluminum foil in quantities larger than a match head though. I'm thinking of mixing some Al powder with melted ETN and running a piece of nichrome wire through it to see if it makes a feasible detonator. In any case, I wouldn't melt ETN with anything other than a water bath, since its melting point is about 80C. Or maybe it would be safer to coat the nichrome wire in glue, then dip it in Al powder, since this would limit the interaction between the ETN and Al more.
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hissingnoise
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[*] posted on 17-3-2010 at 07:50


Yes, but sometimes what sounds like a detonation may just be a 'fast burn'.
The crack of a rifle, for instance. . .
ETN melts at ~61*C but if you're adding Al flakes you need to do the melting remotely, just in case!





[Edited on 17-3-2010 by hissingnoise]
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per.y.ohlin
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[*] posted on 17-3-2010 at 12:29


I know bang does not always mean detonation, but with a small quantity of unconfined ETN I cannot image a bang being deflagration.
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[*] posted on 17-3-2010 at 12:41


In this case i agree with you, MHN and ETN do not have explosive deflagration, at least unconfined.
They might be sensitive but are definitely not primary's.
Its easy to test because deflag. will do next to no damage compared to a detonation.
BP+ETN is very unlikely to det.




What a fine day for chemistry this is.
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[*] posted on 17-3-2010 at 13:03


Look for metal shattering and cutting brisance being demostrated by energetic materials which are known to be capable of that, or else don't be too sure about what is the nature of the bang you may hear is a "detonation". And there are
different orders of detonation possible also. Speculation about what only a
witness plate or other good experimental results may show is no more than mere speculation, until you have the evidence provided by test materials which are
revealing what speculation cannot tell for sure.
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Melgar
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[*] posted on 17-3-2010 at 16:01


Well, the one time I detonated ETN on foil, it was loud enough to make my ears ring and it turned the aluminum foil I was heating it on into tiny bits of glitter. Again, I'm a bit apprehensive about trying more experiments since even a very small amount of this stuff will make a noise loud enough for my neighbors to hear.
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[*] posted on 17-3-2010 at 16:34


How "loud" is an explosion is not really a definitive measure of performance.
There are some compositions that are really loud and you would expect to find
that there was a high order detonation, but there actually wasn't when the
evidence is examined. Really, honestly it does require definitive tests to
determine for certain what the energetic material has done in the way of "work"
on the target, and everything else is guessing. Also the smaller quantity being tested, the less likely it becomes that an actual high order detonation occurred because there is a "critical mass" requirement which varies according to the conditions and the particular energetic material being tested. If you have neighbor worries, then you don't have a safe environment to be conducting any tests necessary to get good data.
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[*] posted on 18-3-2010 at 03:46


Quote: Originally posted by per.y.ohlin  
I know bang does not always mean detonation, but with a small quantity of unconfined ETN I cannot image a bang being deflagration.


A "bang" is simply the noise from a shockwave going faster than the speed of sound...thus slighly faster than 350m/s (1250 km/h) will make a bang!

As stated Rosco, if you are unconfined and in very tiny amount...the chance for a detonation to occure from D2DT is very low because each explosive compound displays specifically what is called a critical diameter of detonation (lowest diameter of a charge at what a detonation (proven by a witness plate) occurs) below this diameter only deflagration occurs. This diameter is defined under confinement...if unconfined it goes up significantly and so does all linked parameters...inclusive the critical mass!

Dc = critical diameter of detonation
Vc = Dc*Dc*Dc = critical volume of detonation
Mc = Vc/d = critical mass of detonation

Important note:Don't confuse the critical diameter of detonation (Cdod) with the critical diameter of the steel sleeve test (Cdosst)...the later being an evaluation of the confinement needed to perform deflagration or detonation of an explosive under direct heating of an iron steel container from flames.
There is an inverse proportionality rule between the later and the former!

Cdod = K(constant)*1/Cdosst

So NH4NO3 has a high Cdod (a few inches) but the lowest Cdosst (1mm) and Nitroglycerin has a low Cdod ( in the order of mm) and the maximum Cdosst (24 mm).

[Edited on 18-3-2010 by PHILOU Zrealone]




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[*] posted on 18-3-2010 at 12:05


Quote: Originally posted by hissingnoise  

The crack of a rifle, for instance. . .


There is a very interesting issue in hand loading that many people call a "detonation". This takes place where a substantially LOWER level of smokeless powder is charged in the cartridge and the result is a catastrophic head case separation & occasionally extreme damage.

There are some complex questions this gives rise to.

Now whether this IS a true detonation or not is something that has not been published in common reloading material; but what takes place is obvious. The volume in the cartridge increases so that the primer's effect on the NC/NG is such that the case cannot contain the power of the explosion. we know that there is a "weak spot" (the seated bullet) purposely designed to use the energy as a work format.
If the that material simply burned - developed gasses, etc, why would the case web not be able to contain the thrust of these gases? The result is not only an insepent case separation but in some instances, a blown receiver or other material damage that occasionally seen as a "shattered" firearm, & at other times a "peel" of the surrounding material. {This is very important as it illustrates the strength of the explosion.} At other times (to make this more complex) the case is separated and the bullet travels through the barrel. That result looks similar to "tired brass" but yet it had occurred with new material and an extreme undercharge.

Remington briefly studied this phenomenon in the mid-1960's when it made more of it's brass available and it was studied again in the early 1990's by independent researchers in the .40S&W when a great deal of Glock pistols had some troubles.

The two issues were vastly separate in that Glock chose not to fully support the cartridge in their chambers but one issue was clear, that pressure spikes -HIGHER than could be dealt with by the brass & steel were occurring with LESS energetic material than would be appropriate to yield such a result.
Two questions came to light. 1.) does this situation of a vastly low powder charge create a DDT? Or 2.) Is the term "propellant" a misnomer, in that a managed explosion was not allowed to mount to full detonation through either lack of available oxygen (volume) or can a detonation be halted in a manageable way to provide force via gases & a primer that is not truly a "detonator design". Does an enormously strong casing exists in a modern firearm but within that casing a "plug" or escape valve exists to accomplish work by interrupting or slowing a chemical decomposition?
I thought the whole issue fascinating & the fact that much material is "trade secret" (out of prying eyes) by *Remington & *Winchester's new short magnums whetted my appetite for more information.
Many of the data gathering mechanisms have been complicated by primary energetic material like silver acetylide which yields no gas when it explodes. It simply breaks down.

The noise is obvious but appearance made by the molecule's degeneration at speed. It fact it would air in it's degeneration front and this "may" be the reason it has sound, yet it does not form gases


* In many of the reloading material of the newer "short magnums" there are strong warnings about loading too low.
What's more for generations there has been very direct warnings directly dealing with this subject in loading magnum pistols too low

[Edited on 18-3-2010 by quicksilver]
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[*] posted on 18-3-2010 at 22:33


Quote: Originally posted by Melgar  
Anyone have any experience with this?


Yes, I have. The ETN detonates. Surprisingly small amounts detonate. I was very surprised. I started with a pin head size wrapped tightly in a small piece of foil about 3 mm square. I placed it on a stove burner, turned it on and waited. A minute later there was a sharp crack, surprisingly loud. The foil disappeared. The burner was coated with a very thin film of silver where the foil had been. It looked like aluminum had been sputtered on electrically. I noticed a slight stinging feeling in my thumb. A foil splinter less than the diameter of a hair was sticking in my thumb. I pulled it out with tweezers. It was in two thirds of its 3 mm length. I was wearing safety googles by no other protection because the amount was only 5 mg or so. I tried this again with a piece the size of a split pea. I stood behind the refrig. The bang rang my ears. It put a dent in the burner element and bent the entire element downward enough so that a pot no longer sits on it without wobbling. For the next few weeks, wherever I looked in the kitchen I would see just barely visible dots of aluminum which had been reduced into a dust, floated in the air and then settled. The pieces were much, much finer than you would see in the finest atomized aluminum dust. They were both detonations. I guarantee you that. The power was to extreme, the destruction of the foil too complete.
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Melgar
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[*] posted on 19-3-2010 at 04:53


Excellent, someone can confirm my findings. I guess now we just need to figure out how to use these properties to make a relatively safe detonator.
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[*] posted on 19-3-2010 at 07:13


Melgar :

Professional "exploding Bridge-wire" detonators utilize blast box designs that are quite expensive. One has an inverter and it used with an automobile or truck another is self contained; but they are not small - nor are they cheap. They range from about $1200 + through 2-3k.
The object is to not only push a great deal of current through the device but to recognize the fact that often a LONG distance of wire will act as a resistor. Especially if it's thin. If it's heavy gauge it will cost quite a bit. Therefore the Nonel concept.

If you didn't want to go that route you could use co-axial cable for a capacitor burst but the cable will certainly have a life. It will need to be inspected often and the ends will be lost. Today, industry uses relay boxes of scrambled signal that's encoding process keeps someone from "dialing the wrong number" on a cell phone. This cuts both the wire issue down to reasonable cost and security maintains itself. but just shooting a bank of photo-flash capacitors down a wire is not going to work well UNLESS you have at the bridge-wire terminus an actual resistance wire such as Nichrome, which is a resistance point as opposed to the rest of the lead. Do NOT be dissuaded to use steel wool or some super thin piece of wire, etc. They will corrode, break, & may not actually focus the point of highest energy where you need it.

If you want to see some god ones check out a search for "Blasting, industrial, Nonel, safety ignition". I don't want to make a link as this is a simple discussion and the company's have concerns of their own, etc.*

You actually could get the effect if you had a automobile inverter with a circuit-breaker @ about 700 watts and make a lead less than 200yds with whatever wire for the lead and leg wires. but that bridge wire needs to be the real thing.



* see a company named Ideal.
One of the reasons why these blast boxes are so expensive is that they put out BOTH current & voltage. They are pretty much lethal @ 1500-2500V & .250ma. And they often use a Ghz frequency that is both encrypted and has a fairly decent transmitter (they can exceed 5 watts).

[Edited on 19-3-2010 by quicksilver]
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[*] posted on 20-3-2010 at 03:30


For a quick blow the peak-Wattage has to be maximized.

That means all the circuit has to be low-resistivity:
==> e.g. 1 Ohm of overall wire-res. will at 1 kV permit a current of 1 kA, giving a mximum of 1 MW, that cannot be exceeded
==> 1 Ohm at 5 kV will permit 5 kA, thereby the limit would be 25 MW ...
==> 0.1 Ohm at 5 kV would permit even 50 kA and thereby 250 MW (though in reality probably limited by inductivity, both of the capacitor and the wires; also violent magnetic fields would lead to dangerous effects) ...
==> But in contrast the photo-capacitor-bank with maybe 500 V would at 1 Ohm only permit 500 A, thereby only 250 kW peak, quite lame in contrast to the higher Voltages

The higher the potential peak-Wattage, the quicker the discharge ...

So the optimum voltage is probably several kV, and the capacitor may even be not too big: Standard caps, which are rated for maybe 500 V, will at least one time each withstand a multitude of that ...


... to be continued ... : Blumelein-Circuit etc.
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Melgar
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[*] posted on 20-3-2010 at 18:21


No, no, no. I'm not talking about an exploding bridge charge. I'm talking about using 5VDC to heat a nichrome wire coated in aluminum and detonating ETN. I know this can be done because I did it myself with a very small amount of ETN. If I did it myself with like 5mg, perhaps with a larger amount, it could be a primer for a more powerful charge. It would certainly seem to be safer than a lot what's currently available.
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[*] posted on 20-3-2010 at 23:20


... continuation from above:

Expensive parts are not necessary, except one DC-charger ...
==> As said above: Each standard-500V-rated capacitor will withstand several kV before breaking ... ; this though does not count for electrolyticals (which are useless for the purpose, since they withstand only maybe 30-50 % over-voltage) ...
==> So one really high-voltage cap will be charged to maybe 5 kV, and then the circuit will be closed, blowing the 500-V-specimen ...

The circuit I initially would construct for the experiment would look like this:
(+ 10 kV) )------(cap1)-------(wire)-------(cap2)------( (- 10 kV)

What happens then is: The 500-V-caps will have been charged to maybe 2 kV, maybe even 4, and in the moment of failure the one that blows first
==> shorts thereby out, permitting half of the energy stored in the other cap. to quickly flow through the wire, thereby detonating it ... if the wire is thin enough for the charges ...

Those 10 kV, mentioned in the circuitry, may come from some standard TV-anode or whatever, and be transferred to the location via coaxial cable ...

Also I would add another cap:

deton.png - 16kB

Cap 3 would have bigger capacity, be close to the location and ensure quick discharge, since the energy would flow through the comparatively small circuit thereby formed, however long the coaxial cable would be ...

]

[Edited on 21-3-2010 by chief]
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[*] posted on 21-3-2010 at 08:02


Guys, he's *not* talking about EBW detonators. There are already threads on that subject; for the layperson to construct the firing circuits is not a trivial task. Please get back on topic.

Melgar - You might try doing a few experiments where you mix varying percentages of blackhead aluminum with a small quantity of ETN. Holiday light strings provide a cheap source of heating elements. Some brands of plastic straws also fit snugly over the glass envelope of the bulb from a holiday light string, making easy disposable assemblies for testing.
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[*] posted on 21-3-2010 at 08:42


Quote:



No, no, no. I'm not talking about an exploding bridge charge. I'm talking about using 5VDC to heat a nichrome wire coated in aluminum and detonating ETN. I know this can be done because I did it myself with a very small amount of ETN. If I did it myself with like 5mg, perhaps with a larger amount, it could be a primer for a more powerful charge. It would certainly seem to be safer than a lot what's currently available.


Sorry to interrupt but this guy is right, I don't understand how this can be unclear...
There is plenty of stuff about EBW's and similar systems lets not waste this thread on that kinda stuff.
The whole deal is that if he's right we do not need a complex and expensive unit.




What a fine day for chemistry this is.
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[*] posted on 21-3-2010 at 10:29


There are two applications.

If timing is not critical use the nichrome wire
or Xmas tree bulb as the heat source. The most simple reliable power source
is just a battery. Something like 4 "D" cells in series should work fine, no need
for any electronics. To be safe connect two normally open push button switches
in series with the battery. That way you need to push both of them to set it off

If timing is critical (on the milisecond scale as in for a FAE setup) then something
like an EBW is needed. A disposable camera contains a 120uf cap which is
charged to 300V by the circuit in the camera. 0.5*120e-6*300^2 = 5 joules of
energy stored in the little cap. This is equivalent to dropping a 1kg weight about
18 inches. If you could deliver all of this energy to the detonator it would easily
set off ETN. I recommend mixing the ETN with enough Al powder to make
it slightly conductive. Then get some cheap speaker wire and strip just a tiny bit
off the end this will create a gap of about 0.128". Somehow imbed the end of the
wire pair into the ETN/AL. This way the current must pass through the ETN
and hopefully most of the heating will occur there. Using the disposable camera
for power see how long you can make the speaker wires and still have it work
reliabily.

Here is a website on how to use disposable cameras:
http://www.jeffhove.com/robots/coilgun.html



[Edited on 21-3-2010 by gregxy]
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[*] posted on 21-3-2010 at 11:15


Anyhow: If it really works with Al for mysterious reasons ...
==> ... then those reasons may probably be found in the electronic structure of Al, which likes only 3fold bonding: So whence an Al-atom once is activated for 1 electron it just "dumps" 2 others, or so to say "requires" immediate 3-fold bonding ...,
==> whhich sort of inversely mirrors nitrogen ... ; maybe in ETN the N-alignments are specially sensitive to that ...

[Edited on 21-3-2010 by chief]
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[*] posted on 21-3-2010 at 14:50


As I understand from above the effect occurs with foil, but not with thicker Aluminum:
==> That means (probably) that an exothermic runaway needs to be possible, which would be hindered by the good thermal conductivity of thicker aluminum ...

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[*] posted on 21-3-2010 at 18:15


Quote: Originally posted by chief  
As I understand from above the effect occurs with foil, but not with thicker Aluminum:
==> That means (probably) that an exothermic runaway needs to be possible, which would be hindered by the good thermal conductivity of thicker aluminum ...


Yes, that could be the case, coupled with the fact that there would be more loss of ETN from thermal decomposition when heated more slowly. I think I'll need to try some more experiments next time I get a chance, maybe by burying each test detonator under a foot or so of dirt. That'd probably minimize the loud noises, plus it's about time to dig up the garden and get it ready for planting anyway. :)
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[*] posted on 22-3-2010 at 04:12


Tillage by IED, Melgar?
Ideally though, such testing should be done well away from built-up areas. . .


[Edited on 22-3-2010 by hissingnoise]
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