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MineMan
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[*] posted on 1-5-2016 at 13:56
Combined Effects Explosives


All,

I have heard a lot of folks bash the addition of aluminum powder for added energy because it does not react along the detonation wave...

Please see the attached presentations, they are very interesting and show that properly sized, the Al or Si powder can contribute to the Gurney velocity, and of course greatly increases the energy. The trick is that an energetic plasticizer must be used, not an inert plasticizer. I have tried Si in ANNM mixtures, it seems to be less sensitive than ANNMAL. One advantage of silicon is it is brittle, making milling easier. I have thought of pushing the use of silicon for commercial explosives, but Al is still a little cheaper...

http://www.dtic.mil/ndia/2012IMEM/13890anderson10B.pdf


Also, the addition of Al between 10-30% increases the duration of the peak detonation pressure several fold... I know for blasting that even a few more miliseconds of pressure makes a large difference, hence why a proper amount of clean crushed stemming is used.


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[*] posted on 2-5-2016 at 10:51


Hmm. BDP (benzenediazonium perchlorate and aluminium powdered to within an inch of its life...



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PHILOU Zrealone
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[*] posted on 3-5-2016 at 14:39


Quote: Originally posted by MineMan  
All,

I have heard a lot of folks bash the addition of aluminum powder for added energy because it does not react along the detonation wave...

Please see the attached presentations, they are very interesting and show that properly sized, the Al or Si powder can contribute to the Gurney velocity, and of course greatly increases the energy. The trick is that an energetic plasticizer must be used, not an inert plasticizer. I have tried Si in ANNM mixtures, it seems to be less sensitive than ANNMAL. One advantage of silicon is it is brittle, making milling easier. I have thought of pushing the use of silicon for commercial explosives, but Al is still a little cheaper...

http://www.dtic.mil/ndia/2012IMEM/13890anderson10B.pdf


Also, the addition of Al between 10-30% increases the duration of the peak detonation pressure several fold... I know for blasting that even a few more miliseconds of pressure makes a large difference, hence why a proper amount of clean crushed stemming is used.



Remains to see comparative datas from unaluminized vs aluminized Explosives on:
-Lead block test 10g
-Sand crushed test 1g
-Fragmentation test
-VOD mesurements
-Blast pendulum test

It is conceivable that if the Al has a reduced oxyd layer and a fine mesh enough with the perfect % and an appropriate explosive (between positive OB, zero OB or a slighly negative OB) that the oxygen taken away as Al2O3 allows for sufficient energy to compensate for (or surpass) the energy for CO formation instead of CO2...but Al must not be pushed too far in% as to form only C...what would be detrimental...
So conventionnal nitroaromatics have too low a negative OB to be of interest for that specific effect/application.

[Edited on 3-5-2016 by PHILOU Zrealone]




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[*] posted on 3-5-2016 at 16:02


PHILOU,

Those are some really good points. But what about those explosives, such as AN mixtures, and maybe ideal explosives which create H20 vapor upon detonation? Even if the explosive was OB%- the aluminum should strip the oxygen molecule from the H20. I know they tried high percentages 10-20% in ANFO, but the issue they encountered was and excess of hydrogen gas because of that mentioned above. The quarries were not all that happy with fireballs emitting from the rocks several minutes after the blast...
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[*] posted on 3-5-2016 at 16:38


PHILOU,

I also forgot to mention, in my last post the powepoint shows the VOD, it is about a 5% drop. This is true for adding Al to ANFO also, it certainly does help with rock fragmentation. But again, with the case of blasting the explosive is confined underground allowing several more mili seconds of reaction time. 100-200mesh is used for blasting, in the form of flakes.
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PHILOU Zrealone
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[*] posted on 5-5-2016 at 03:58


Quote: Originally posted by MineMan  
PHILOU,

I also forgot to mention, in my last post the powepoint shows the VOD, it is about a 5% drop. This is true for adding Al to ANFO also, it certainly does help with rock fragmentation. But again, with the case of blasting the explosive is confined underground allowing several more mili seconds of reaction time. 100-200mesh is used for blasting, in the form of flakes.

What powerpoint are you refering to? I only see pdf's




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Herr Haber
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[*] posted on 6-5-2016 at 18:33


Philou,
If you look at the compositions used in explosives from WW2 (widely available) you'll notice that many are hugely OB defficient yet include a lot (up to 20-30%) aluminium for increased blast effect. VOD might suffer, but depending on what your purpose is an increased blast can be more desirable.
Just have a look at the different Torpex compositions for example.
There are many TNT + your nitramine of choice + a lot of aluminium compositions out there.
On the other hand, when I look at small caliber (german 20mm flak for example) ammo they tend to favor oxygen balanced compositions.
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[*] posted on 6-5-2016 at 23:23


An integrated sort of aluminium-dispersing thermobaric composition might be interesting (I mean Al mixed with TNT in such a way that the TNT explodes, forms the Al into a fine powder and then burns the cloud of Al dust.)



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[*] posted on 7-5-2016 at 10:05


Quote: Originally posted by Herr Haber  
Philou,
If you look at the compositions used in explosives from WW2 (widely available) you'll notice that many are hugely OB defficient yet include a lot (up to 20-30%) aluminium for increased blast effect. VOD might suffer, but depending on what your purpose is an increased blast can be more desirable.
Just have a look at the different Torpex compositions for example.
There are many TNT + your nitramine of choice + a lot of aluminium compositions out there.
On the other hand, when I look at small caliber (german 20mm flak for example) ammo they tend to favor oxygen balanced compositions.

I know!
I was refering to Mineman documents and the subject of the tread.

I wrote:
"So conventionnal nitroaromatics have too low a negative OB to be of interest for that specific effect/application."
The post detonation thermobaric effect was not considered here, nor the explo-implosion effect of nano Al sponge dopped with TNT.
Only the effect onto the detonation process that needs good intimity/viccinity of oxygen and Al to allow "immediate" reaction in the detonation zone.

True that Blast pendulum and LBT will benefit from detonic effect but also from the post blast/detonation reactions.




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[*] posted on 7-5-2016 at 11:42


Philou

you are right they are both PDFs. Sorry for the confusion :). In regards to the ANFO, that comes from industry experience.

I know this is an effect we have known about for a long time, but I think the authors did some great additional work on it. Everything I have searched about in regards to Boron does not seem that promising, maybe the oxide layer is harder to burn through..., and I believe it uses more oxygen per weight. Al powder sells to industry at about $1.20lb... that is pretty hard to beat.
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