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AirCowPeaCock
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You do know after you release the pressure it will just go back to its original size, right? And I'm pretty sure it will take tons of pressure to
even make a 1/100s difference. Try tempering(?)
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chrisgedwards
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i just thought that compressing explosives would also lead to more energy per unit volume which maybe necessary to project such super dense
projectiles from a gun. I dont have access to these papers right now but someone may. interesting stuff.
I mentioned some sort of container for the compresseed metal core. im wondering how long it would take for it to expand. as mentioned earlier , there
are some metal joints that are compressed permanently for high altitude and deep sea stuff. the question is how compressed can something be and have a
long shelf life.
http://jcp.aip.org/resource/1/jcpsa6/v124/i2/p024712_s1?isAu...
http://www.amazon.com/Detonation-Condensed-Explosives-High-p...
not sure these are what i think they are. do you think its possible to compress a volume of rdx into 1/10 the size without it detonating? this would
allow for all sorts of superpowerful mini devices including in projectiles...
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chrisgedwards
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the first paper i posted above has some great info in it, now that i have acquired it.
the change in volume at around 4 GPA was roughly 25% for rdx (if i remember correctly). some explosives investigated actually got down to almost 1/2
the volume.
intermolecular spacing is what im trying to shorten here and under these pressures (which arnt too high) it appears that both explosives and metals
can have their densities increased. now the question becomes how far can the be compressed, for how long and at what cost?
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watson.fawkes
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And for very good reason. You persist with a basic theme, that there
are materials whose density can be manipulated by an order of magnitude. This theme does not occur in nature. People keep telling you this, and you
persist. How is this not grounds for ridicule?
Density limits are governed by the Pauli exclusion principle, incidentally.
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chrisgedwards
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That doesn't mean basic and persistent themes don't have any value. If my asking questions with regards to topics (quarter shrinkers, railguns,
degenerate matter, the energy of projectiles, young's modulus) is not in line with what you guys want here at sciencemadness, so be it. But shooting
down people wanting to honestly discuss science is very exclusionary. People who are honestly interested in discussion ought to be treated with some
respect. Yes yes, i won't be missed, but with the general attitude of this board (and some members specifically,) I won't miss posting to
sciencemadness. Ill lurk like so many other nervous people must.
Im not sure why my ideas have been shot down, especially after posting articles that support my thoughts -- illiciting some positive responses.
However, I sure feel shot down personally. I hope that this doesn't happen to all non-experts that post here. The foundations of science and amateur
science boards such as this, have always been shaped by those who think differently of set principles.
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AirCowPeaCock
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I'm talking about metals, not explosives. Of course some explosives can be compressed a great deal. And I think its safe to assume of done carefully
enough it can be pressed to its absolute density.
[Edited on 1-24-2012 by AirCowPeaCock]
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Panache
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Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
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Sorry if it appears that we are having fun at your expense, well we are but it's absolutely nothing personal. Its just that your concept makes
absolutely no practical sense.
Yes, a denser projectile is something of value, and you explain quite accurately why this is so.
Yes some materials can be much denser if at the bottom ocean, considerably so.
But unless you are wanting to use those projeciles there, musings regarding density increases that require outrageous conditions are quite simply
boring, why, because they are impractical.
so perhaps you misread the nature of the dissent, and maybe we could have been nicer about it. I hope you are not discouraged.
I'm not sorry about my wicked jokes because they were pretty fucking good but maybe they were not appropiately used herein.
Happy new year!
Edit 46532pelling erors
[Edited on 24-1-2012 by Panache]
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Pulverulescent
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| Quote: | If my asking questions with regards to topics (quarter shrinkers, railguns, degenerate matter, the energy of projectiles, young's modulus) is not in
line with what you guys want here at sciencemadness, so be it. But shooting down people wanting to honestly discuss science is very exclusionary.
People who are honestly interested in discussion ought to be treated with some respect. Yes yes, i won't be missed, but with the general attitude of
this board (and some members specifically,) I won't miss posting to sciencemadness. Ill lurk like so many other nervous people must.
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─Chris, I must apologise to you for my overly dismissive attitude!
Simple tolerance of the views and ideas of others is something I appear still not to have learned!
I'm just a fucking asshole and shouldn't be taken too seriously on any point!
But don't leave; I really am working on it . . . ?
P
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fledarmus
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Of course it would be great to have a denser, harder bullet. Depleted uranium is used precisely for that reason. Delivering more energy to a smaller
cross-sectional area increases penetration, which is what armor-piercing is all about.
But throwing things like "2-3x the density", "1.5x the weight", and "superdense" without any indication that such materials exist isn't helping your
argument a bit. Show us a phase diagram - under what conditions of pressure and temperature can you form a material of the appropriate density, and is
it stable once those conditions are removed?
I remember years ago reading a science fiction story which used compressed iridium-cobalt projectiles, I believe. The shell had a bullet which
consisted of an explosive wrapped around the iridium-cobalt form, and when fired, the explosive would compress the form into a super-dense projectile.
I don't remember the name of the book, and I've never seen any science that suggests this is possible.
As for your compressed steel, I believe this is a hardening process - the density increase is very slight, but the crystallization is controlled to
provide a very hard, tough form. Very much like the traditional blacksmith's method of hammer-hardening.
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Pulverulescent
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| Quote: | | Depleted uranium is used precisely for that reason. Delivering more energy to a smaller cross-sectional area increases penetration, which is what
armor-piercing is all about. |
The crystal structure within a rod of DU is such that when used as a projectile, it is essentially 'self-sharpening'!
That is to say that, on making contact with armour-plate at high velocity, DU shears off in layers which are partially longitudinal to the axis and it
is this which increases the power of penetration relative to projectiles made of other materials . . .
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Neil
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Not to mention cost; tugston is expensive, dU is waste disposal.
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Pulverulescent
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Material costs are not of great concern to the military, but tungsten lags well behind DU in its penetrating ability . . .
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AirCowPeaCock
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not to mention DUs ability to be very hot on impact. Yes maybe if you had a Iridium-iron alloy you could have a much denser projectile, but talk
about this when we start mining asteroids and comets--but then again, when that happens, it will be done the first day the military gets their hands
on cheap iridium, if it ever happens.
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Neil
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Really? I thought Tungsten was the better of the two but that it was more expensive and lacked the pyrophoric qualities of DU?
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AirCowPeaCock
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Wiki
Ir Density (near r.t.) 22.56 g·cm−3
W Density (near r.t.) 19.25 g·cm−3
And I don't know how common tungsten is in space, but I know we find lots of meteorites containing ppms of Ir--which is really alot if you think about
it.
wiki
Ir Annual production of iridium circa 2000 was around 3 tonnes or about 100,000 troy ounces (ozt). 2010 635$/ozt.
W About 61,300 tonnes of tungsten concentrates were produced in the year 2009.
[Edited on 1-24-2012 by AirCowPeaCock]
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AirCowPeaCock
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But then when you compare that to osmium
Density (near r.t.) 22.59 g·cm−3
Its price at 2010 is about $400 per Troy ounce (or about $13 per gram). Still cheaper than pot though--gram for gram
but fighting with osmium bullets would be like fighting with tiny nukes, as far as environmental damage goes.
[Edited on 1-24-2012 by AirCowPeaCock]
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Neil
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...I was actually aiming that question at Pulveresence. But I have to hand it to you, that is the first time I've ever seen metal prices related in
terms of pot buying power...
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AirCowPeaCock
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its a first for me too
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AirCowPeaCock
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although its less expensive than Ir
Neither the producers nor the United States Geological Survey published any production amounts for osmium. Estimations of the United States
consumption date published from 1971,[44] which gives a consumption in the United States of 2000 troy ounces (62 kg), would suggest that the
production is still less than 1 ton per year.
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AirCowPeaCock
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DU take advantage of its very high density of 19.1 g/cm3, just short of W. but cheaper and again, with the potential to go critical on impact--or
that's what Ive heard. Ive heard of rounds with explosives on the end of the bullet that force the DU through the armor, but I don't know if this is
true.
wiki
Depleted uranium is favored for the penetrator because it is self-sharpening and pyrophoric.[26] On impact with a hard target, such as an armored
vehicle, the nose of the rod fractures in such a way that it remains sharp. The impact and subsequent release of heat energy causes it to disintegrate
to dust and burn when it reaches air because of its pyrophoric properties.[26] When a DU penetrator reaches the interior of an armored vehicle, it
catches fire, often igniting ammunition and fuel, killing the crew, and possibly causing the vehicle to explode.
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Pulverulescent
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In its use as AP rounds by the tank-guns of MBTs armour piercing by DU is to do with kinetic energy alone!
And uranium is pyrophoric only when finely divided . . .
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dann2
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DU use for armaments is a bit like Flourine use for drinking water.
It's a waste product from the nuclear industry that would be difficult to get rid of. It's creates 'no problems' when used to do what it does.
If someone were to obtain DU and fire the stuff around New York, the place would be evacuated untill it was cleaned up.
Dann2
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AirCowPeaCock
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Again wiki The impact and subsequent release of heat energy causes it to disintegrate to dust and burn when it reaches air because
of its pyrophoric properties.[26]. The 26 is a dead link, but apparently its from the US dept. Of energy
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unionised
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"DU take advantage of its very high density of 19.1 g/cm3, just short of W. but cheaper and again, with the potential to go critical on impact"
Not really. That's what the "depleted" bit means.
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AirCowPeaCock
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Depleted means its been decayed from "regular" uranium, its still radioactive, but your right, it probably doesn't go critical on impact, but it does
heat up because it gets less sub-critical--or at-least that's what wiki seems to imply, and it has to make at-least some difference. <-- run-on
sentence 
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