Sciencemadness Discussion Board

Super dense projectiles

chrisgedwards - 13-1-2012 at 09:37

Hey everyone,


I was watching show about deep sea diving the other day and got an idea. some deep sea diving suits are made from metal that is compressed into super dense individual components that can handle the pressure of the deep sea.

I was wondering if it would be possible to compress a metal such as lead or depleted uranium so that the density was significantly higher. This super dense projectile would carry much more energy than a projectile of the same size but of lower density.

after doing some searching, im not seeing anything regarding current technology similar to this. what do you guys and gals think?

unionised - 13-1-2012 at 10:30

I think the compressibility of metals is so absurdly small that this is nonsense.
Either the show was wrong or you misunderstood it.

Mr. Wizard - 13-1-2012 at 11:11

The energy of projectiles has nothing to do with the density, and is dependent on mass and velocity; E=1/2 m v^2. That said I know what you might be asking is how the energy can be kept high while traveling through air and into a target. Most metals cannot be made more dense by compression then returning to normal conditions.

As to metal being strong enough to handle pressure at great depths, I don't think the density has much to do with it. Some very dense metals are very strong, but strength ultimately comes from the electrons bonding with each other, and their arrangement. Diamonds come to mind as an example of a light material, with strong bonds, arranged in an optimal fashion for hardness. There is a general correlation between melting points and hardness, but the different hardness between diamond and graphite show how important the arrangement is.

There was a joke once that Chevy Vegas were made of compressed rust ;)

neptunium - 13-1-2012 at 12:02

only nature knows how to compress mater in the core of dying stars...
down here on earth we can make artificial diamonds by heating and compressing graphite but the atoms rearange themseves as previously explained..

paulr1234 - 13-1-2012 at 12:12

There are many examples of technology 'systems' (frequently with military application) that are designed to perform optimally in extreme environments.

The Navy's current ADS (atmospheric diving suit) has joints that actually function better when at the intended depth (down to 2,000 feet).

So what you saw and heard probably wasn't referring to the properties of the materials that are used to make the individual suit components but rather how they are designed to perform when subjected to pressure as complete system (or subsystem).

Anther interesting example are the fuel tanks for the old SR-71 spyplane. At the time of manufacture, there were no sealing materials that could withstand the high frictional temperatures created by this aircraft. So instead the plane was designed to use a low volatility fuel (which was also pumped around the fuselage as part of the cooling system) and the tanks and pipes were designed with metal on metal joints, that would leak a little when on the ground.

As the plane took off and increased in speed, thermal expansion would seal the leaks and the plane would operate normally.

chrisgedwards - 13-1-2012 at 12:54

Ive been searching for the episode, no luck yet. They were compressing stainless steal (or aluminum? or titanium?) in large presses. this was something i saw years ago, ill try to find it. I believe that the multiple ATM of pressure in the deep sea could compress the metal parts leading to a malfunction in the suit. so the metal was pre-pressed. im not talking about density's similar to seen on black dwarfs, or anything like this. Metals are high mass but other elements or compounds maybe heavy enough and more easily compressed?

meanwhile, superdense aluminum has been made with a process which involved a laser and a sapphire, which was small and hard to maintain http://www.sciencedaily.com/releases/2011/08/110 825152726.htm

The density does have to do with the energy the bullet caries. as was stated the energy of the projectile changes with the mass and velocity. A bullet of lead of a certain volume will have less energy, when shot at the same velocity, than a bullet the same volume and shape made of highly compressed (superdense) metal (or other material). I wonder if there is any technology that could contain the metal under this high pressure as a jacket, like the copper on a lead bullet. Kevlar like. This could even be made to fragment on impact but that's getting ahead of things...

If the metal when compressed can be as heavy as 1.5x the weight, it can deliver a lot more energy. expensive ammo! maybe its the sort thing that could be launched from a massive rail gun. There is also the idea of a hypervelocity highly heat resistant reentry projectile which falls/ is powered from orbit and into the earth much like a meteorite. twice the mass could mean a lot more power.

obviously im asking just out of curiosity and to have the discussion, i know this is crazy stuff.

Pulverulescent - 13-1-2012 at 13:37

Quote:

The density does have to do with the energy the bullet caries. as was stated the energy of the projectile changes with the mass and velocity. A bullet of lead of a certain volume will have less energy, when shot at the same velocity, than a bullet the same volume and shape made of highly compressed (superdense) metal (or other material). I wonder if there is any technology that could contain the metal under this high pressure as a jacket, like the copper on a lead bullet. Kevlar like. This could even be made to fragment on impact but that's getting ahead of things...

Déjà vu . . . again!
Non-military, sporting bullets are copper-plated to protect the interior (especially the rifling) of the barrel from the fouling effects of the lead in the slug!
Lead-cored steel-jacketed bullets are of the military type . . .
Quote:
i know this is crazy stuff.

You got that part right! :cool:
Superdense? :D

P

Pulverulescent - 13-1-2012 at 13:49

I'm not denigrating you or your posts, BTW ─ just saying you should take what's in "popular science" pubs. cum grano salis! :)

P

Neil - 13-1-2012 at 14:34

google "coin shrinking"

chrisgedwards - 13-1-2012 at 14:41

this is just something that popped in my head, thats all.

superdense is one search term i have been using when trying to find out of anything like this has been done. Superdense is also the term that was used in the published paper i posted a link to.

I know what the purpose of the copper metal jacket is. What i was saying was, maybe if a material can be treated to make it superdense, to keep it in this state, to contain it with a Kevlar (or something stronger) case to stop it from "inflating" or decompressing.

I have a 5 pound lead weight here in front of me, its for diving. feeling this lead, it really seems like with enough pressure it could be compressed into a smaller calendar.

any idea what material has the highest density? i keep seeing osmium but that obviously would be out of the question for use because of the rarity. if lead is 11.34g per ml numbers in the 50 to 100g/ml would lead to massive change in the energy. hypervelocity projectiles have been done, im sure this is possible to some degree.

chrisgedwards - 13-1-2012 at 14:43

oh yes coin shrinking! how did that not come to mind? ill do some reading on it and see what its limits are. ive made a tesla coil and have started but not finished a hv capacitor bank for coin shrinking, but this was like 6 years ago. thanks for the idea!

watson.fawkes - 13-1-2012 at 16:05

Quote: Originally posted by chrisgedwards  
What i was saying was, maybe if a material can be treated to make it superdense, to keep it in this state, to contain it with a Kevlar (or something stronger) case to stop it from "inflating" or decompressing.
In the case of a bullet, you want to decompress always in the target and never in the barrel. This would require a mechanical failure rate less than, oh, 10^-6 say as not to kill shooters regularly. Good luck with getting that to work.

Yes, the above paragraph is entirely sarcastic.

Pulverulescent - 13-1-2012 at 16:32

Quote:
google "coin shrinking"

Interesting effect, this 'coin shrinking'; it's new to me . . .
And it's interesting too, that weight reduction seems to have escaped mention?
It's a 'surface electrical effect', obviously, and the fact that the vaporised metal layer seems so uniform and precise could, quite possibly have applications in some field of engineering!
Quote:
I know what the purpose of the copper metal jacket is.

Do you not think that calling a few microns of copper plating a 'jacket' is stretching it just a bit? :D
And kevlar, FFS, is just a synthetic fibre!!!
Coin shrinking, considering the power-levels used, could result in producing a plurality of candidates for the 'Darwin Award'

P

chrisgedwards - 13-1-2012 at 16:44

really this is not something im planning on doing, just something i was curious about. why so much sarcasm?

is it really that strange to wonder if a bullet can be made of a material that is significantly more dense than lead?

im still looking but i did find Chengdeite which is iridium iron alloy. iridium cost a lot so in the last few years it looks like its gone from 500 to 1000$ an ounce. Chengdeite is Ir3Fe and has a density near 20g/cm3. Obviously too expensive. im going to keep looking, im sure there is something that could work. The price of the round must also be considered against the cost of an explosive round that would do the same amount of damage.

it appears that coin shrinkers make the diameter of the coin smaller but the coin gets wider. i read that the density is not changed. im wondering if electromagnetic forming can be used to increase the density. maybe if a container were used that did not allow for the width of the coin or projectile to widen.

im trying to find the data but not having much luck (surprise!) on plutonium type implosion devices. im wondering about changes in density of the resulting plutonium sphere when it is compressed by the shaped explosive charge.

anyone ever hear of a hypervelocity reentry projectile? something like a man made meteorite?

according to several sites, .50 caliber bullets have masses around 400g, lets call it a pound. imagine a .50 caliber bullet weighing in at 2-3 pounds and the amount of energy it could do a supersonic speeds. i just think its an interesting idea.

Sedit - 13-1-2012 at 17:20

Sorry but its a little off topic, would the pressure at the bottom of the ocean be enough to form a diamond if the carbon was in the proper form at the time? If so what would be the depth needed? I will run the numbers later if I have time but I am about to head out for the night and was curious.

chrisgedwards - 13-1-2012 at 17:35

right now im reading up on degenerate matter. scientist have made degenerate matter in small amounts. This sor tof density is way more than required to make such a projectile but the science is very interesting.

“This experiment resulted in something like a micro-explosion which turned the aluminium to a plasma state that swelled but had nowhere else to go, creating gigantic pressure and dramatic changes in surrounding material properties and producing unfamiliar x-ray spectral lines.

http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1031...

concerning diamonds i found this (yes from wiki oh well) The process involves large presses that can weigh hundreds of tons to produce a pressure of 5 GPa at 1500 °C. bottom of the mariana trench is only 110 mpascals.

Neil - 13-1-2012 at 18:26

They took the idea of bundles of arrows fired from a catapult and made bundles of U238 and or Tungsten rods fired from an ICBM. The USA does ot use them because the minute anyone anywhere see's an ICBM signature, red buttons get pushed.


So they do have re-entery weapons which are much denser then lead. look for lit on the new Trident missles.

chrisgedwards - 13-1-2012 at 20:08

of course whenever i have an idea its already been done. so much for the hypersonic superdense reentry weapon...

so now my focus is on making small superdense projectiles for use in railguns.

does anyone know anything about degenerate matter?

Pulverulescent - 14-1-2012 at 01:44

Quote:
does anyone know anything about degenerate matter

"Degenerate matter" . . . that would seem to be Hawking Territory!
Heeeaaavveee . . . !

P

Panache - 14-1-2012 at 02:36

I'm going to get a
Degenerates Matter!, Tshirt made up. Might startup up a facebook page titled as such also. Actually i know absolutely i'll do neither of these two things but my life is richer for the possibility of being able to.

Just made up a joke
Q: what did the talk show star's fanbase write on their protest banners after she was axed from the network?
A: Ellen Degenerates Matters!

Pulverulescent - 14-1-2012 at 04:05

Degenerate matter; wasn't that one of Hitler's pet hates?
Ooops! Sorry, I got Art and Matter mixed up!
Shit! I suppose I've Hodgkined the thread now . . .

P

Neil - 14-1-2012 at 04:46

Hissing noise made less noise :P

lol ellen.

degenerate matter would be a weapon all on its own as it would *pop* without the immense force needed to maintain its state. The energy needed to make and contain degenerate matter is so far beyond anything you could even imagine that to put it in context you would be more likely to have a breakthrough researching ways to cold fuse bananas to produce blast waves.

No human will ever *see* degenerate matter.

As for rail guns, leekage between the rails saps the propelling power. A railgun slug would need to be non-conductive Eg. Teflon coated.

Pulverulescent - 14-1-2012 at 05:34

Quote:
Hissing noise made less noise :P
Don't you mean even less noise, Neil? ;)
And anyway, the hissing noise in pulverulescent is 'silent' . . . :o
Just like the P in bath! :D

P

Neil - 14-1-2012 at 05:39

touche, I think? That felt like a mental rickroll.

chrisgedwards - 23-1-2012 at 15:09

Alright, im not being taken seriously.

Do you guys see an advantage to using a tungsten carbide jacketed projectile with 2-3x the density and thus mass per unit volume instead of a bullet of the same size that is 1/2 or 1/3 the weight? less drag, less space, more energy. like shooting a 50 cal bullet from a 22.

This is the technochemistry section of science madness not weapons design so i wanted to keep my language research minded as opposed to mentioning specifics on the projectile design and the damage it will do, hence terms such as pop etc. im trying to discuss basic science here with out upsetting anyone but its proving difficult.

Obviously degenerate matter is huge overkill, i was using it as an extreme to show how matter can be compressed.

Meanwhile i have done some reading on the subject to try to keep these post on topic.

I am a biology student not and engineer which should be obvious and evidence that this is just out of curiosity..

Now am i right to believe that the youngs and bulk modulus of each material will determine how feasible it is to reduce the volume of a given mass? a lot of the numbers i am seeing related to these equations appear to only be for elasticity and not compressability. where could i look?

As mentioned above machines used for making diamonds or explosives (also used for diamonds) are the two methods that could allow for the production of these projectiles. Picking a material that is cheap enough to use is also essential (no iridium etc). Also since tungesten carbide and tungsten appear to be the usual pieces used for these presses, am i right in believing that the same materials could not be used in one of these contraptions?

Looking at a few sites i see a list of the compressability of several types of materials. Ideally the material will already be quite dense (at least 10g/ml) and will have a very low energy of compressability.

anyone want to let me know if i am reading into the wrong thing? i wish i could find a proper calculator online that would easily tell me the pressure needed to half or 1/3 or even quarter a materials volume.

Interesting combinations of super dense (good term), armor piercing, caseless ammunition is interesting. I am also wondering about rocket/typical bullet hybrids modeled sort of like the original caseless ammo, the rocketball by walter hunt.

AirCowPeaCock - 23-1-2012 at 15:20

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(?)

chrisgedwards - 23-1-2012 at 15:55

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...

chrisgedwards - 23-1-2012 at 16:20

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?

watson.fawkes - 23-1-2012 at 16:26

Quote: Originally posted by chrisgedwards  
Alright, im not being taken seriously.
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.

chrisgedwards - 23-1-2012 at 18:09

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.

AirCowPeaCock - 23-1-2012 at 18:52

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]

Panache - 23-1-2012 at 22:54

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]

Pulverulescent - 24-1-2012 at 02:57

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.

─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

fledarmus - 24-1-2012 at 05:59

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.

Pulverulescent - 24-1-2012 at 06:23

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 . . .

P

Neil - 24-1-2012 at 06:28

Not to mention cost; tugston is expensive, dU is waste disposal.

Pulverulescent - 24-1-2012 at 07:08

Material costs are not of great concern to the military, but tungsten lags well behind DU in its penetrating ability . . .

P

AirCowPeaCock - 24-1-2012 at 07:26

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.

Neil - 24-1-2012 at 07:44

Really? I thought Tungsten was the better of the two but that it was more expensive and lacked the pyrophoric qualities of DU?

AirCowPeaCock - 24-1-2012 at 07:56

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]

AirCowPeaCock - 24-1-2012 at 07:59

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]

Neil - 24-1-2012 at 08:08

...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...

AirCowPeaCock - 24-1-2012 at 08:10

its a first for me too

AirCowPeaCock - 24-1-2012 at 08:11

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.

AirCowPeaCock - 24-1-2012 at 08:19

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.

Pulverulescent - 24-1-2012 at 10:02

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 . . .

P

dann2 - 24-1-2012 at 10:24



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

AirCowPeaCock - 24-1-2012 at 10:39

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

unionised - 24-1-2012 at 11:23

"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.

AirCowPeaCock - 24-1-2012 at 11:27

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 ;)

Neil - 24-1-2012 at 11:27

When you take all the U235 out of a sample of U and are left with only U238 it is depleted aka waste. storing it was expensive so they switched to dispersal...

fledarmus - 24-1-2012 at 11:42

One of the other uses for depleted uranium is for radioactive shielding. This is not a significantly radioactive material. It is, however, a toxic heavy metal, very poisonous to ingest.

Neil - 24-1-2012 at 11:50

I would be interested in some references on the shearing/self sharpening nature of DU rods, sounds interesting. I've been reading about ballistic tiles and impact modeling and haven't come across it before.

AirCowPeaCock - 24-1-2012 at 12:03

Okay, I have been served wrong--or at-least mostly. But that's cool, radioactive shielding using radioactive material! How well does it stand up next to good old Pb?

dann2 - 25-1-2012 at 08:53


With regards to 'quarter shrinkers' the quarters are not shrunk at all. They just change shape and look much smaller. The can crushers compress cans surly but thay are full of air.

Tungsten is used as a substitute by the US Navy (instead of DU) AFAIK.