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Dany
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Another evidence that support Pepekin conclusion (that the limited Dcj is arround 11 km/s and that there is a limiting detonation velocity
in explosives materials). This time the evidence is from the vibrational frequencies of a particular atom pairs in explosive molecule.
F. E. Walker, Description of a Shock-Wave Velocity Barrier, Propellants and Explosives 6, 15-16 (1981).
Dany.
Attachment: Description of a Shock-Wave Velocity Barrier.pdf (202kB)
This file has been downloaded 744 times
[Edited on 21-9-2013 by Dany]
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caterpillar
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Another simple thing just came to my mind. Assume, we can initiate detonation of the whole piece of explosive in an instant (no matter how: electrical
discharge, light beam, jet of protons and so on). In such case pressure in shock wave will be smaller, than in case of, let's say, "natural"
detonation, initiated from one small part of explosive. In case of "natural" detonation shock wave is result of interference of shock waves, generated
by any particle of explosive. There will be no such interference, if a whole piece goes off in in instant. Therefore, even if some trick to get super
speed of detonation is possible, brisance will suffer.
Women are more perilous sometimes, than any hi explosive.
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Ral123
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Quote: Originally posted by caterpillar  | | Another simple thing just came to my mind. Assume, we can initiate detonation of the whole piece of explosive in an instant (no matter how: electrical
discharge, light beam, jet of protons and so on). In such case pressure in shock wave will be smaller, than in case of, let's say, "natural"
detonation, initiated from one small part of explosive. In case of "natural" detonation shock wave is result of interference of shock waves, generated
by any particle of explosive. There will be no such interference, if a whole piece goes off in in instant. Therefore, even if some trick to get super
speed of detonation is possible, brisance will suffer. |
I've had the idea that casual cheap explosives can have high velocity core, to initiate all the volume of the material at once, but I also feel, the
reduced time to complete reaction this way, wont contribute to more efficiency.
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Dany
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Ral123,
the idea of a "cheap explosives can have high velocity core, to initiate all the volume of the material at once" is not true. Putting a high
detonation velocity core explosive will set a curved detonation wave in the whole explosive charge. you can imagine this like an inverted cone
detonation wave. so no instantaneous detonation. the reaction still need time to complete. this principal is not new, it is known as wave shaping.
Plane wave lens used in detonation experiment uses this technique (wave shaping) to set a plan detonation wave in an acceptor charge. generally the
Plane wave lens is formed by two cone of high explosive, with the outer cone formed by a "fast" explosive (e.g., HMX-based explosive) relative to the
inner cone formed by a "slow" explosive (e.g., baratol). An important conference on wave shaping can be found here:
http://www.dtic.mil/dtic/tr/fulltext/u2/128529.pdf
Dany.
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Ral123
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May be the idea isn't worth it for most applications. Imagine a 10 tons rock that must be split. A hole is made for dynamite. If the dynamite has high
velocity core, more force will try to split the rock at once.
You have access to pretty interesting documents.
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franklyn
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Hydrogen molecules exist in two types with respect to spin state of their electrons. The ratio of spin isomers
depends on temperature. It is 3 moles orthohydrogen (parallel spin) to 1 mole parahydrogen (antiparallel spin) at ambient conditions. It is never
possible to obtain a sample containing more than 75 % of orthohydrogen because the ortho form is an excited state and has a higher energy than the
para form , it is unstable and cannot be gathered. It is possible to obtain pure parahydrogen , hydrogen molecules are almost entirely of the lower
energy para state at cryogenic temperatures. A gas of unpaired hydrogen atoms near absolute zero in a very high magnetic field align antiparallel to
the magnetic field and do not form into diatomic molecules. Research to produce monoatomic hydrogen entirely of the parallel spin orthohydrogen is
ongoing. Recombination of a metastable monoatomic form into molecules releases 10 's of times more energy by weight than conventional energetic
chemistry , but at greater volume due to the very low density of hydrogen.
It should be understood that spin is a quantum property which does not involve mass transport or energy transfer so there is no time limitation for
transition between states. Spin polarized hydrogen can change orientation without time as a constraint , as it requires no time to do so. This
suggests that reaction speed of this type of energetic process has no fundamental limit since the rate is already effectively infinite.
Ultra Cold Methods for Polarized Atomic Hydrogen
http://deepblue.lib.umich.edu/bitstream/handle/2027.42/87438/119_1.pdf?sequence=2
Separation of Water into Its Ortho and Para Isomers
Abstract here _
www.sciencemag.org/content/296/5577/2363
Download PDF
www.sciencemag.org/content/296/5577/2363.full.pdf
.
[Edited on 23-9-2013 by franklyn]
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Microtek
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But even if the spin transition can occur in no time, the actual recombination into molecular hydrogen cannot. So, the energy release will not be
instantaneous.
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simply RED
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"Hydrogen molecules exist in two types with respect to spin state of their electrons."
No! With respect to spin state of their PROTONS. Acc to the quantum mechanics H2 molecule has one sigma bonding and one sigma* antibonding orbital.
http://i48.photobucket.com/albums/f221/Corribus/hydrogen_mol...
Of course the electrons occupy the sigma orbital with antiparalel spin and every attempt to excite to sigma* will break the molecule.
When logic and proportion have fallen sloppy dead...
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watson.fawkes
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That paper
you posted has nothing to do with "parallel spin orthohydrogen", which is a state of diatomic hydrogen H2 involving alignment of proton
spins (as already stated). The paper is about electron spins aligned with an external magnetic field. About the only things they share are hydrogen
atoms and spin, in other words, not much.
Primer on ortho- and para-H2: http://en.wikipedia.org/wiki/Spin_isomers_of_hydrogen
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PHILOU Zrealone
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| Quote: Originally posted by Dany | Another evidence that support Pepekin conclusion (that the limited Dcj is arround 11 km/s and that there is a limiting detonation velocity
in explosives materials). This time the evidence is from the vibrational frequencies of a particular atom pairs in explosive molecule.
F. E. Walker, Description of a Shock-Wave Velocity Barrier, Propellants and Explosives 6, 15-16 (1981).
Dany.
[Edited on 21-9-2013 by Dany] |
I just reread this article and found evidence that the theory simply doesn't hold the line at least it is very insufficient.
They explain the VOD limitation of High Energy Explosive Material at 10,3 km/s (+/- 11 km/s) by the highest vibration of C-H or N-H bond frequency
based on Infrared absorption spectra.
Sole problems are that:
1°) any explosive containing C-H or N-H with the same density should then detonate at the same speed not regarding their OB, amount of explosophoric
groups or energy content.
2°) non hydrogen explosives like hexanitrobenzen and octanitrocubane should detonate at very low detonations speeds because they only contain C-C,
C=C, C-N, N-O, N=O bonds what resonates in IR with very much lower frequencies than C-H or N-H ones...so VOD should be folowing their theory in the
range 5-6km/s while they are both practically in the 9-10 km/s range.
They also postulate that:
a)In the detonation proces propagation of the wave is only vibrational and not radiative or electromagnetic in nature.
--> But what is IR by definition...radiative emission/absorption of electromagnetic field.
b)After the wave has passed higher vibrational frequencies may occur...
--> Thus in the detonation products behind the detonation wave...
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Dany
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PHILOU,
this article simply try to explain that detonation velocity of CHNO high explosive is limited by the vibrational frequency of the bond that make up
the system. Regardless of the detonation velocity of a specific explosive, a "limiting" value for Dcj is reached which is governed by the
vibrational frequency of the atoms. In fact the author didn't said that the 10.35 or 11 km/s cannot be exceeded, he said:
"It is not intended to imply that the barrier cannot be exceeded but rather that there is a significant decrease in energy efficiency as the
barrier is exceeded."
The conclusion set by the author about this barrier (like the sonic and thermal barrier explained in the paper) comes from the experimental evidence
that until now thousands of organic explosive CHNO explosive have been synthesized but none (until now) can exceed the 10 km/s which make the
vibrational frequency barrier hypothesis very likely.
If in the future an organic CHNO, CHN or even CN explosive will exceed the 11 km/s than we will review and critics this hypothesis.
Dany.
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chemister2015
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Will metallorganic compounds have high VoD? Example (CH3)2Ti(ClO4)2?
In article Propellants, Explosives, Pyrotechnics Volume 37 issue 3 2012 pp. 335-344 VoD is higher 15 km/s.
P.S.: I'm sorry for my English.
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Metacelsus
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How would one even make that compound, let alone isolate it? It looks ludicrously unstable.
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a nitrogen rich explosive
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It would be. Personally, I am working on a complex of tetrammine copper hexamethylene triperoxide diamine perchlorate. The peroxide ion is very
uncomfortable with the Cu+ ion, which would make this an extremely sensitive and powerful explosive.
I can't think of a better signature.
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PHILOU Zrealone
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| Quote: Originally posted by chemister2015 | Will metallorganic compounds have high VoD? Example (CH3)2Ti(ClO4)2?
In article Propellants, Explosives, Pyrotechnics Volume 37 issue 3 2012 pp. 335-344 VoD is higher 15 km/s.
P.S.: I'm sorry for my English. |
Very interesting. Do you have the article for me or a picture of that page stating 15 km/s.
Usually Metals are a dead weight for explosives and induce lower VOD...see heavy metals primaries have usually VOD <7 km/s and most of the time
between 3 and 6 km/s.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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PHILOU Zrealone
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| Quote: Originally posted by a nitrogen rich explosive | | It would be. Personally, I am working on a complex of tetrammine copper hexamethylene triperoxide diamine perchlorate. The peroxide ion is very
uncomfortable with the Cu+ ion, which would make this an extremely sensitive and powerful explosive. |
If you take infos from another poster, at least take the info right!
Cu(2+) not Cu(+)!
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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a nitrogen rich explosive
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Sorry Philou...
The famous Hideki Matsumoto said thus:
Just discussing Octonitrocubane and the power this molecule has with a contact of mine! Turns out that the military thinks that the detonation
velocity of this compound could be in the neighbourhood of 91Km/sec (over sublight speeds). This would make this compund almost as powerful as a
nuclear weapon! WoW the Cubane molecule has apparently 166KCal per mole of energy! I will see what I can come up with on how it is put together!
I can't think of a better signature.
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Dornier 335A
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| Quote: Originally posted by a nitrogen rich explosive | Sorry Philou...
The famous Hideki Matsumoto said thus:
Just discussing Octonitrocubane and the power this molecule has with a contact of mine! Turns out that the military thinks that the detonation
velocity of this compound could be in the neighbourhood of 91Km/sec (over sublight speeds). This would make this compund almost as powerful as a
nuclear weapon! WoW the Cubane molecule has apparently 166KCal per mole of energy! I will see what I can come up with on how it is put together!
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91 km/s? What a load of rubbish. Octanitrocubane would reach just over 10 km/s if the predicted high density crystal structure could be
achieved. Furthermore, the explosive contains just above 8 MJ/kg (~1.7 times as much as TNT) while nuclear weapons like the Tsar Bomba comes
in at around 8 TERAjoules per kilogram.
Have you heard about source criticism?
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a nitrogen rich explosive
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Oh, christ no! I was joking!
Someone on this forum a while ago got banned after saying this... I know that this is shit!
I can't think of a better signature.
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Microtek
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Philou:
I read the paper referenced above (the one with 15 km/s). It is a purely theoretical paper on nitro-functionalized boron containing molecules. Since
the molecules are speculative, the densities are difficult to estimate. For this reason, they calculate the detonation parameters at a range of
densities (1.3 to 2.0 g/cc), and the model gives very high figures for VOD (and to a lesser degree, Pcj). The paper is written by Klapötke's group,
and they note that there are several potential problems with the model.
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PHILOU Zrealone
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| Quote: Originally posted by Microtek | Philou:
I read the paper referenced above (the one with 15 km/s). It is a purely theoretical paper on nitro-functionalized boron containing molecules. Since
the molecules are speculative, the densities are difficult to estimate. For this reason, they calculate the detonation parameters at a range of
densities (1.3 to 2.0 g/cc), and the model gives very high figures for VOD (and to a lesser degree, Pcj). The paper is written by Klapötke's group,
and they note that there are several potential problems with the model. |
OK thanks.
I have also a dozen of putative molécules with VOD >10km
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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a nitrogen rich explosive
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Can you U2U me some of them for me to evaluate?
I can't think of a better signature.
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MineMan
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Will a VOD change from 10km/s to 11km/s make a difference? I would think at a certain point that changes in VOD would be negligible. Has anyone
performed a test where an EBW was run through the whole length of a product to simulate a very very high VOD ( in the longitudinal direction only
though).
CL-20 shows 40% more depth penetration in shape charges than HMX... with only a 400-600m/s difference, but it also has a higher energy density, and
crystal density. I am just speculating that at some point, maybe after 10-12km/s a change in VOD won't make that much of a difference, does the
equation for Detonation Pressure become irrelevant at that point.
Danny, I know you are a wizard with these kinds of questions...
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a nitrogen rich explosive
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Well, 10km/s to 11km/s is a 10% change... However, there is a point where VoD becomes irrelevant because of the diffusion of energy throughout the
object.
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Dornier 335A
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Changes in VoD are certainly never negligible. Detonation pressure is the important parameter in things like shaped charges. It is related to the
detonation velocity according to the following formula:
PCJ = ρ DCJ2 / (1 + γ)
where γ is the adiabatic index (~3 for high density solid explosives) and ρ is the loading density.
So small variations in VoD gives large changes in pressure. For example, HMX at max density has about 4% higher VoD than RDX, but 15% higher
detonation pressure.
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