Dornier 335A - 14-5-2013 at 07:00
What phase does a salt or a metal have at detonation temperatures and pressures? Is the pressure high enough to cause a salt like NaCl or a metal like
magnesium, that has a boiling point and a critical point well below normal detonation temperatures, to become solid?
I've searched for phase diagrams and other data but only found if for common gases and carbon. Is there software available to calculate phases at
different temperatures and pressures?
franklyn - 14-5-2013 at 11:40
What happens in the compression zone of an ideal explosive just ahead of
the reaction zone should be obvious. If it was solid or liquid it remains that
until actual chemistry results from heating by adiabatic compression and it
then becomes a plasma. The time frames involved do not allow for phase
change as that requires more time than is available.The products of detonation
that result behind the wave condense rather quickly as they cool down. The
action of the explosion upon nearby matter in the case of compaction from
the momentum of the blast will not be the same as it is within the explosive
material. Powders of arbitrary composition , metal , ceramic , etc. are instantly
fused into an aggregate of welded particles similar to granite. This of course
means that solids flow plastically under the extreme pressure applied. Possible
outcomes are the shocked material is only disrupted otherwise remaining
unchanged although deformed. A solid material may be liquefied and
instantaneously congeal as a glass without definite crystal form. If sufficient
latent heat remains , the material will crystallize normally. The behavior of
each material differs in response to the particular conditions to which it is
subjected. Size is also a limiting condition. A Taggant for example , is a color
coded microscopic plastic chip contained in explosives that survives to be
retrieved from the debris , identifying the material used. Survivability decreases
with the size of the explosive charge and its power. The survivability of individual
taggants in large explosive charges or in military grade explosives has not been
demonstrated.
Properties of state for most metals and inorganic material are found in _
International Critical Tables of Numerical Data, Physics, Chemistry and Technology
www.knovel.com/web/portal/basic_search/display?_EXT_KNOVEL_D...
Detonation in Shocked Homogeneous High Explosives
www.osti.gov/bridge/servlets/purl/207590-XOVWBq/webviewable/207590.pdf
Engineering Design Handbook - Principles of Explosive Behavior AMCP 706-180
www.dtic.mil/dtic/tr/fulltext/u2/900260.pdf
Joining Enabled by High Velocity Deformation
http://etd.ohiolink.edu/send-pdf.cgi/Zhang%2520Peihui.pdf?acc_num=osu1061233577
High Explosives The Interaction of Chemistry & Mechanics
www.galcit.caltech.edu/EDL/projects/JetA/reports/BillDavisHE.pdf
Some Metallurgical Aspects of Shaped Charge Liners
http://cdn.preterhuman.net/texts/terrorism_and_pyrotechnics/explosives/Shaped_Charges_Penetrators/Some_metalurgical_aspects_of_shaped_charge_liners.pd
f
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Dornier 335A - 15-5-2013 at 11:19
Thanks for the links Franklyn.
I realize now that my question might have been a bit unclear. I'm asking if metals and salts formed in the reaction are gaseous at the CJ point where
the chemical reactions have reached equilibrium and the temperature is maximal. Carbon for example will very quickly coagulate to form solid particles
since gaseous carbon don't exist at detonation pressures. (http://commons.wikimedia.org/wiki/File:Carbon_basic_phase_di...) Is this the case for other normally solid products? I know that all compounds
will differ slightly but is there a general rule?
franklyn - 16-5-2013 at 02:40
You're talking about the formation of products from the explosion.
The explosive reactants must start as plasma. " The products of
detonation that result behind the wave condense rather quickly as
they cool down." I imagine any substance exists as a supercritical
fluid momentarily before that. A phase whether gas , liquid , or
solid is not relevant to individual atoms or molecules not attached
to others in a lattice since it is an aggregate property. You can have
lone molecules of water at near absolute zero floating around
independently which negates the notion of being solid.
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