>Because, as the people of Kuwait discovered after first Gulf War, depleted uranium leaves a potentially deadly dust behind after it burns. It sounds bizarre but, in the world of warfare, tungsten is the eco-friendly alternative.
"Armour penetration is increased by concentrating the force of a shell into as small an area as possible, so the projectiles tend to look like giant darts. [ ... ] The other metal used for anti-tank rounds is tungsten, which is also very hard and dense. When a tungsten rod strikes armour, it deforms and mushrooms, making it progressively blunter. Uranium is "pyrophoric": at the point of impact it burns away into vapour, so the projectile stays sharp. "
For penetrators you want density, hardness, and other penetration aiding properties. Tungsten is very dense, but as you point out it blunts when hitting a target, reducing its effectiveness (but if you have enough it'll still work).
The guardian article you linked is a little bit off on the properties of Uranium. Uranium is self sharpening (which means that when it slams into a target it fragments splinters off, leaving behind a sharp point). Uranium is also pyrophoric, which doesn't mean that it burns away pieces into vapor, rather it means that when it scrapes along as it's penetrating through metal it throws off sparks, just as flint and steel does. Additionally, Uranium is more flammable than Tunsten. This means that a long rod Uranium penetrator can punch through thicker armor than Tungsten and it spits out a rain of sparks and splinters as a burning hypervelocity rod comes through the other side of the armor. This leads to a very bad day for the target.
However, because of that pyrophoricity and that burning the result of using lots of DU shells on hardened armored targets is a lot of DU dust and vapor. Because Uranium is a toxic heavy metal this can have disastrous health effects.
> However, because of that pyrophoricity and that burning the result of using lots of DU shells on hardened armored targets is a lot of DU dust and vapor. Because Uranium is a toxic heavy metal this can have disastrous health effects.
Well, I imagine being hit by a tank round has so profoundly disastrous health effects anyway, the metal toxicity doesn't matter much!
(Yes, I know you probably meant adverse health effects for the people who wander into the area after the crew is killed, much like it happens with nukes, but still. The considerations are bizarre, like the article said)
People live in warzones. People live in warzones just after they've been warzones. This is even more true in urban warfare. This is why the civilized world tries very hard to avoid using landmines in war, and why there's so much effort into preventing civilian casualties with unexploded munitions like cluster bombs, for example.
There is an argument to be made on whether or not the risk of collateral damage is justified, it's impossible to make war completely "safe", of course, but with DU the evidence is stacking up that the collateral damage is extreme and probably not a good tradeoff.
The misconceptions about DU in the media always irritate me. People hear "Uranium" and immediately start talking about radioactivity, but the D in DU should remind them that the whole point of DU is that it's significantly less radioactive than naturally occurring Uranium. I can find more radioactive rocks lying on the ground only a few hours drive from where I live.
DU, considered as a radioactive substance, has low radioactivity and low biological half-life. From that narrow point of view, it's really quite innocuous.
Uranium is, however, a reactive heavy metal, and breathing those as dust has never been good for you, whatever the metal (as those downwind of industrial plants with poor environmental oversight will be happy to tell you.)
1) "the whole point of DU is that it's significantly less radioactive than naturally occurring Uranium"
The D in Depleted (U-238) has nothing to do with it's radioactivity but that it's not fissile. Fissile U-235 is not too badly radioactive either (4 billion vs. 0.7 million year half life i.e. 77% more radioactive 0.5^(0.7/4) / 0.5).
We don't make depleted uranium to have less radioactive uranium (naturally occurring uranium is < 1% U-235). We have DU because we made nuclear bombs.
Interestingly the Ruskies have made DU arms far more expensive now with their breeder reactor (U-238 is fertile).
2) DU is an alpha emitter. I would bath in a bathtub made of alpha-emitters and sleep in a bed of alpha-emitters.
However, Uranium shatters making dust. I would not want to breath, eat, drink an alpha-emitter. It's a heavy hitting He ion that will knock the socks off anything in it's short path.
Not to mention U-238 becomes Th-234 with a half life of 24 days (very radioactive) with beta emission (ouchy!). There'll never be a lot of Th-234 (U-238's low radioactivity) but it'll all decay into you (Th-234 small nuclear half-life and large biological one).
So U-238 effectively decays in your body as a an alpha and beta!
What happens when you blow up DU? Gets scattered throughout the local environment.
3) ...Low biological half life
That's only relevant for disaster tourists. For people whose environment has been seeded with the stuff, the biological half life is completely irrelevant as it is replenished as you eat, breath and drink. An equilibrium concentration is therefore established.
Therefore, environmental half-life is far more important than a biological one.
I'm not advocating DU as a part of a healthy diet. It's more than 100 times as radioactive as bananas, after all. I am saying that the primary danger from DU is not its radioactivity, but the fact that it's a heavy metal. That still true (possibly even more true) in an area with excessive DU contamination.
The fissibility of Uranium isotopes is critically important in weapon design and storage. With regard to biological danger, it's the radioactivity that is important (unless you happen to be near a prompt critical event, of course). DU is about half as radioactive as natural Uranium, so I think my "significantly" was justified.
Body burden and biological half-life are better indicators of a given radioactive substance's danger to living creatures, especially in the case of alpha emitters. That's why proactive measures like prophylactic iodine and showers are effective in contaminated areas. Of course accumulating more doses of an agent is always going to be more dangerous---what's important in comparisons is how dangerous one dose is.
Your Th-234 argument is misleading, and you know it. Yes it's nasty, but U-238 decays to Th-234 with a half-life of 4 billion years. That event would occur in a human body so rarely as to be completely immeasurable unless the human was contaminated with so much U-238 they'd die instantly from the toxic exposure and whatever horrific event deposited that much.
We ingest alpha-emitters with every meal, and while we should avoid ingesting more than we have to, at the small rates we do even in the presence of U-238 (or a diet rich in Bananas and Brazil Nuts, for that matter), there's no statistical impact on lifespan.
There are large tungsten deposits outside of China. The issue is, China has such a monopoly it controls the price.
I have been apart of at least three Tungsten Mine pre-feasibility studies. All they need to do is ramp up production, and the price falls to a point where NPV of your tungsten project falls to zero.
Prices aside, you probably also don't want to introduce a dependency on china in your weapons supply chain. This I believe was also the primary reason for the GM bailout.
Possibly the idea that a large number of subcontractors and suppliers would also have gone out of business.
I think it would be difficult to determine which rationales were sufficient to get enough votes for the bailout to pass, but the cost of creating a supply from scratch after a period of zero demand from GM might have been far more expensive to the aggregate economy than the bailout was. Therefore the cost was judged 'worth it' in spite of the implicit reward to GM for decades of mismanagement.
The bailout can still have been a sweetheart deal for the creditors of the company, but it didn't do the old GM any good.
I tend to think the motivation of the bailout was to reduce disruption in the job market, I don't think there would have been much more than a short term disruption in the OEM business.
There's actually an entire non-big3 industry which manufacturers military hardware in the US. Your point about not wanting foreign dependencies is a good one though (see also strategic oil reserve).
PhenQ est publié en février 2015 par RDK Pharmaceuticals pour ceux qui essaient de perdre du poids en tant que brûleur de graisse de qualité pharmaceutique. Il y a une différence dans l'identification des termes car il n'y a pas de «r» dans Phentemine au lieu de la phentermine commune. http://www.phenqavis.org/
Funny to see this article here now. For the last few weeks I've been geeking out on exotic materials, and especially Tungsten Carbide. I even went so far to buy a polished Cobalt binded TC 70mm sphere from China. It's virtually indestructible and very few materials such as diamond can scratch it.
It's not cheap. I contacted almost all suppliers worldwide, and in EU the price is roughly 2000-3000 EUR for a single sphere. However, one supplier in China called Sintec had in stock for a mere USD 375. It's a grade 50 sphere with a precision of a few thousands of a millimetres:)
That's an unusual material for a ring, I just hope you don't get into the situation where it needs to be cut off. That would put me off using such a hard metal for rings and jewellery chains.
You can't cut it. But the Carbide is brittle and with enough pressure it can shatter Carbide ring manufacturers have this in mind and intentionally make "weak points" on the ring so it can be removed in an emergency.
You can also do it using a pair of Vise-grips. Just adjust the tool so that the closed mouth is slightly smaller than the ring. The ring will break but not hurt the finger.
My experience with metalworking indicates carbide endmills and inserts are incredibly brittle, slapping hand very hard against a brick (like high-fiving a brick wall) would probably shatter it.
If you drop an endmill (like a drill bit but different, about the size of your thumb) from a normal carrying height to a concrete floor, you'll almost certainly be buying a new endmill; much like dropped buttered toast always seems to land butter side down, a dropped end mill always seems to land point down and crack a big chip off. A ring should be lighter so less stress, and smooth would imply no stress concentration points, but I'd still be careful about impacts or dropping it.
Another anecdote is interrupted cuts on a metal lathe will shatter carbide seemingly instantly every time, you need to use "old fashioned" high speed steel to cut anything with a gap. I wonder if the vibration of taking a diamond tip engraver to a carbide ring would shatter the ring instantly.
An interesting anecdote is a rather large lump of carbide for a replaceable indexable cutter is a couple bucks and a rod of carbide turned into a polished sharpened precision endmill of a large size is only maybe $30. Possibly the ring could cost more because that specific type of carbide looks very nice or has been stress relieved or annealed somehow to make it less brittle, and of course there's the labor time of a professional jeweler if its custom work. But the raw material, unlike gold or Pt, can't cost more than perhaps $100 for a carbide ring.
I got mine because it was just nerdy, and I liked the weight of it. Plus if I'm ever in a plane crash, I know at least a little bit of finger will survive.
"It's virtually indestructible and very few materials such as diamond can scratch it."
Not really. It's a ceramic and as such will shatter if knocked against another ceramic, hardness notwithstanding. Also, for some reason, my skin eats away at it.
See my tungsten carbide ring vs my fiance's ring (mine is on the left) - both made before the requirement that the rings come with break points built-in -
https://i.imgur.com/fSIOUJf.jpg
Note the differences - his ring looks brand new. Both rings bought at the same time, same maker, same style.
Note that your ring is not really representative of real tungsten carbide. WC is a sintered material so the amount of binder (cobalt) and the size and makeup of the WC powder is extremely important. Even among tungsten inserts there are types designed for continuous turning and types for interrupted turning, which have a much higher toughness.
Toughness is what determines energy before breaking and note that while many ceramics are not at all tough, high end technical ceramics are tougher than most metals[1]. High quality WC is indeed tougher than steels. It's also twice as strong as most steel, but high-end steels surpass it in strength.
"Toughness is what determines energy before breaking"
With ceramics and glass, things get a little tricky. You can take a relatively weak and softer piece of pottery ceramic and obliterate the hardened bullet-resistant windows on police cars (the laminate inbetween being a different matter, but the glass itself will shatter/crack.) That happens via ultrasonic frequencies created on impact.
> With ceramics and glass, things get a little tricky. You can take a relatively weak and softer piece of pottery ceramic and obliterate the hardened bullet-resistant windows on police cars [...] That happens via ultrasonic frequencies created on impact.
All of that is wrong. You can't use pottery shards or even hard pebbles to break glass; you need very hard technical ceramics[1]. Spark plug ceramic is alumina which is extremely hard.
It has nothing to do with ultrasonic frequencies, it's caused by crack propagation. Tempered glass is under internal stress due to its quench rate and chemical treatment, so as soon as the outer shell is broken the entire thing shatters. Alumina is so hard that a corner can chip off a bit of glass, releasing that pressure.
Ceramics can't be tempered like glass, and like untempered glass they only shatter if an impact by a much harder object is above the fracture propagation energy. That means that most of the time the impact energy is about the same as the actual toughness of the material. For high toughness ceramics there are no materials hard enough to cause chipping, so they break exclusively under normal toughness.
"You can't use pottery shards or even hard pebbles to break glass; you need very hard technical ceramics[1]. Spark plug ceramic is alumina which is extremely hard."
Plenty of pottery contains aluminum oxide, which is very hard.
That's not the same thing- coal contains microscopic diamonds but you'll have a hard time scratching sapphire with it. Incidentally, alumina is much closer to sapphire than any pottery. Alumina is the sintered powder form and you need really good quality, high density stuff to be able to break a window. It's also a near-requirement that it has very sharp points.
Alumina will effortlessly scratch gorilla glass, any metal, tungsten carbide and even a lot of sapphire glass. No kind of pottery will do any of those things.
"coal contains microscopic diamonds but you'll have a hard time scratching sapphire with it."
Coal dust will abrade and destroy almost everything and it's because of the graphite, not the diamond. I have a coal mine. It's killed two phones and a drone already.
"Alumina will effortlessly scratch gorilla glass, any metal, tungsten carbide and even a lot of sapphire glass. No kind of pottery will do any of those things."
This is entirely untrue, it depends on the composition of the clay used in making the ceramic, which will be entirely dependent upon the location the clay or clay mix is obtained from. I also happen to do lapidary and pottery work, as a profession (next to LED lighting applications.) You can get clay from Mt. Baldy, make pottery, fire it up, it will scratch the hell out of almost everything because of the sand grain-sized rubies contained within.
If you're interested then have a read about the development of Chobham and Dorchester armour. There is very little detail out there but fascinating to see how some of the military kit is made and what it can stand up to.
Interesting. In the SciFi series (and books) The Expanse the rail gun projectiles were tungsten. I thought it was just due to the heat resistance of tungsten but it might have been chosen by the authors for the additional property of density. I wonder if the electrical properties make it suitable for the mechanisms used for rail gun propulsion.
It's almost always chosen for density in scifi- most early railguns used tungsten because the density means you can have a very small cross section per unit mass, meaning low wind resistance which is important at super and hypervelocity. Of course it's irrelevant in space, but it carried over to sci-fi anyway.
It's really not the perfect metal for neither bullets or missiles.
Tungsten will strip out any barrel, even normal copper jacketed bullets can strip a barrel after a few 1000's of rounds.
Some calibers are prone to stripping more than others which is why some high end rounds will be covered by a polymer coating that adds lubricity and protects the barrel (it also has the benefit of dampening some inconsistencies in the barrel itself which can improve precision).
Tungsten given enough velocity will go through pretty much anything, this isn't something you want with bullets both because you usually do not want bullets to go beyond their targets and that a bullet needs to be able to dump it's energy into the body to be effective.
Small caliber through and throughs leave much less tissue damage unless hitting a vital organ and even then a larger, slower round that deforms would transfer more energy to the target.
The velocity of the bullet has a hard limit and that is the energy that is stored in the chemical propellant.
As for missiles tungsten is heavy as fuck, it's denser than Uranium and Lead you want your missiles to have as long of a range as possible, be as fast as possible (to be harder to intercept) for that you need them to be as light as possible.
If you can make your missiles take on more weight and you've already achieved the desired range and velocity then you better off just putting more stuff that goes boom than an inert metal that does nothing.
Tungsten, just like high carbon steel and depleted uranium is useful for only one thing and that is penetrating armor, in those cases you would optimize your penetrator for that task meaning you'll be using a small narrow profile (basically a dart, or well a flechette) which moves really fast and can compromise heavy armor.
The only real use for tungsten in traditional projectiles it to defeat composite reactive armor that would make shaped charges and other traditional anti armor munitions less or completely in effective.
Even in those cases the tungsten penetrator is more often used to either disable the vehicle by destroying it's engine block, turret controls, suspension and tracks or by compromising the main body armor and then finishing it off with a explosive anti armor around that would also cause crew casualties (in a war of attrition killing the tank crew is often more important than destroying the tank).
It's also important to note that tungsten penetrators are often not made out of pure tungsten since it blunts (relatively) easily, so carbides and other really hard materials would be used to make it even more effective.
Besides that Tungsten might be useful for gravity penetrators basically "bunker busters" although in that case DU and lead might be just as potent unless you are limited by the size of the bomb itself.
Lastly the only other real use of Tungsten is in DIME warheads, these warheads employ inert metal powder as the force delivery mechanism, they fill their effective area with micro-shrapnel that pretty much would tear and liquify all tissue within it's blast radius but due to the high density of the metal and the limited explosive charge have a very small blast radius for intended lethal zone reducing direct collateral damage to zero.
IIRC the A1 actually ditched the tungsten core, it's a "lead free" round not AP, the M855 was supposed to be an "environmental friendly" round the tungsten isn't a penetrator really it's some sort of composite matrix but after studies showed that Tungsten is just as bad an even worse than lead as far as the environment goes they've redesigned the round.
The M855A1 is also lighter than the M855 so if my memory serves me correctly they've switched to a mild steel core.
The M955 does use a tungsten carbide penetrator and is classified as an AP round but the usual "green tip" (or well just "green" ammo now since the A1 doesn't have a tip color) ammo that is in use uses steel penetrators for the most part.
M885 was originally designed as basically a copper coated tungsten penetrator, but the M885A1 now is steel tipped with solid copper body. Turns out the tungsten core made it loose it's spin during flight and caused tumbling.
Not sure they saved themselves a lot of money, copper is $. I knew they were trying a tin alloy at one point, not sure what happened to that other than Google saying "Unstable at high temperatures", which is interesting.
The M855 was supposed to be a round that would leave less environmental impact both in actual use and in training.
Tungsten ended up being just as toxic (
The round also had stability and terminal ballistics issues but that is another topic) as lead so they've replaced that one in the M855A1 with mild steel.
Then they had a fancy jacket made out of bismuth and tin alloy that appeared to be both not exactly environmentally friendly especially for the users due to buildup of bismuth salts firearm and unstable at high temperatures which causes inconsistencies in accuracy when fired from a hot barrel.
So they've pretty much moved back to a copper alloy half jacket and an arrowhead steel tip insert, the M855A1 also didn't solve all balsitis issues and ended up being slightly longer which can cause feeding issues.
Ah... I'll have to lookup the bismuth salts forming. That was the missing piece I couldn't find.
Most of my barrels are ferritic nitrocarburized, so they should be impervious to anything... guessing that the US armed forces might have as fancy bore linings.
IIRC it was something to do with the bismuth interacting with powder and primer residue.
And don't be surprised if military guns are less decked out than yours they are built to costs.
Also remember that it's how often you clean your barrel and how many rounds you fire.
The M855A1 was designed to used in both assault rifles and LMGs so something like a SAW would fire 1000s of rounds before it can be properly cleaned up.
Even an M4 would probably be much less cared for while on active duty than your match grade rifle.
>Tungsten's only rival for this kind of application is the radioactive element uranium. Depleted uranium is (almost) as dense as tungsten and has an added advantage - from a military perspective - that it burns at the extreme temperatures generated as you punch your way through steel tank armour.
It's also self-sharpening (ie rather than smooshing like plastic on contact, parts break off and leave a sharp edge behind like flint), and because it's effectively subsidized by power generation and the nuclear program it's extremely cheap compared to Tungsten. Tungsten alloys are tougher[1] (actually, some of the toughest materials period) but penetration depends heavily on the armor type.
Hell, tungsten is toxic too and the military's biggest motivation is probably just as a really effective PR move. Uranium is definitely worse though, and I'm glad the US doesn't use it in munitions much. Uranium forms oxides that are very bioavailable (and even absorbed as gas through the lungs), and are really bad for you and even worse if you get pregnant.
Isn't drag essentially quadratic to speed? Isn't needed input energy also quadratic to speed, while momentum is linear to both mass and speed? Hardness aside don't you have much harder hitting bullets with these heavy elements?
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[ 3.1 ms ] story [ 90.0 ms ] threadTungsten, wolfram, makes the steel so hard.
It goes thru the side of an army tank as tho it were a paper card.
If you want to rule the world, never mind wrong or right,
All you got to have is tungsten wolframite.
[1] https://www.youtube.com/watch?v=qbhP6b_2IUE
i knew it is bad, just googled and according to some sources it is really bad, especially when it comes to birth defects : http://www.huffingtonpost.com/craig-considine/us-depleted-ur...
It is not necessary radioactivity that makes DU that bad, it is its toxicity that does it. Unfortunately, DU is still better for armor penetration : https://www.theguardian.com/world/2000/may/18/armstrade.koso...
"Armour penetration is increased by concentrating the force of a shell into as small an area as possible, so the projectiles tend to look like giant darts. [ ... ] The other metal used for anti-tank rounds is tungsten, which is also very hard and dense. When a tungsten rod strikes armour, it deforms and mushrooms, making it progressively blunter. Uranium is "pyrophoric": at the point of impact it burns away into vapour, so the projectile stays sharp. "
The guardian article you linked is a little bit off on the properties of Uranium. Uranium is self sharpening (which means that when it slams into a target it fragments splinters off, leaving behind a sharp point). Uranium is also pyrophoric, which doesn't mean that it burns away pieces into vapor, rather it means that when it scrapes along as it's penetrating through metal it throws off sparks, just as flint and steel does. Additionally, Uranium is more flammable than Tunsten. This means that a long rod Uranium penetrator can punch through thicker armor than Tungsten and it spits out a rain of sparks and splinters as a burning hypervelocity rod comes through the other side of the armor. This leads to a very bad day for the target.
However, because of that pyrophoricity and that burning the result of using lots of DU shells on hardened armored targets is a lot of DU dust and vapor. Because Uranium is a toxic heavy metal this can have disastrous health effects.
Well, I imagine being hit by a tank round has so profoundly disastrous health effects anyway, the metal toxicity doesn't matter much!
(Yes, I know you probably meant adverse health effects for the people who wander into the area after the crew is killed, much like it happens with nukes, but still. The considerations are bizarre, like the article said)
It's also toxic for the people firing the rounds because blowing up a cartrigde will also evaporate some trace amount of the bullet.
People live in warzones. People live in warzones just after they've been warzones. This is even more true in urban warfare. This is why the civilized world tries very hard to avoid using landmines in war, and why there's so much effort into preventing civilian casualties with unexploded munitions like cluster bombs, for example.
There is an argument to be made on whether or not the risk of collateral damage is justified, it's impossible to make war completely "safe", of course, but with DU the evidence is stacking up that the collateral damage is extreme and probably not a good tradeoff.
DU, considered as a radioactive substance, has low radioactivity and low biological half-life. From that narrow point of view, it's really quite innocuous.
Uranium is, however, a reactive heavy metal, and breathing those as dust has never been good for you, whatever the metal (as those downwind of industrial plants with poor environmental oversight will be happy to tell you.)
The D in Depleted (U-238) has nothing to do with it's radioactivity but that it's not fissile. Fissile U-235 is not too badly radioactive either (4 billion vs. 0.7 million year half life i.e. 77% more radioactive 0.5^(0.7/4) / 0.5).
We don't make depleted uranium to have less radioactive uranium (naturally occurring uranium is < 1% U-235). We have DU because we made nuclear bombs.
Interestingly the Ruskies have made DU arms far more expensive now with their breeder reactor (U-238 is fertile).
2) DU is an alpha emitter. I would bath in a bathtub made of alpha-emitters and sleep in a bed of alpha-emitters.
However, Uranium shatters making dust. I would not want to breath, eat, drink an alpha-emitter. It's a heavy hitting He ion that will knock the socks off anything in it's short path.
Not to mention U-238 becomes Th-234 with a half life of 24 days (very radioactive) with beta emission (ouchy!). There'll never be a lot of Th-234 (U-238's low radioactivity) but it'll all decay into you (Th-234 small nuclear half-life and large biological one).
So U-238 effectively decays in your body as a an alpha and beta!
What happens when you blow up DU? Gets scattered throughout the local environment.
3) ...Low biological half life
That's only relevant for disaster tourists. For people whose environment has been seeded with the stuff, the biological half life is completely irrelevant as it is replenished as you eat, breath and drink. An equilibrium concentration is therefore established.
Therefore, environmental half-life is far more important than a biological one.
The fissibility of Uranium isotopes is critically important in weapon design and storage. With regard to biological danger, it's the radioactivity that is important (unless you happen to be near a prompt critical event, of course). DU is about half as radioactive as natural Uranium, so I think my "significantly" was justified.
Body burden and biological half-life are better indicators of a given radioactive substance's danger to living creatures, especially in the case of alpha emitters. That's why proactive measures like prophylactic iodine and showers are effective in contaminated areas. Of course accumulating more doses of an agent is always going to be more dangerous---what's important in comparisons is how dangerous one dose is.
Your Th-234 argument is misleading, and you know it. Yes it's nasty, but U-238 decays to Th-234 with a half-life of 4 billion years. That event would occur in a human body so rarely as to be completely immeasurable unless the human was contaminated with so much U-238 they'd die instantly from the toxic exposure and whatever horrific event deposited that much.
We ingest alpha-emitters with every meal, and while we should avoid ingesting more than we have to, at the small rates we do even in the presence of U-238 (or a diet rich in Bananas and Brazil Nuts, for that matter), there's no statistical impact on lifespan.
I have been apart of at least three Tungsten Mine pre-feasibility studies. All they need to do is ramp up production, and the price falls to a point where NPV of your tungsten project falls to zero.
I can think of the Hummer, but that wasn't GM https://en.wikipedia.org/wiki/AM_General .
I think it would be difficult to determine which rationales were sufficient to get enough votes for the bailout to pass, but the cost of creating a supply from scratch after a period of zero demand from GM might have been far more expensive to the aggregate economy than the bailout was. Therefore the cost was judged 'worth it' in spite of the implicit reward to GM for decades of mismanagement.
https://en.wikipedia.org/wiki/Motors_Liquidation_Company
The bailout can still have been a sweetheart deal for the creditors of the company, but it didn't do the old GM any good.
I tend to think the motivation of the bailout was to reduce disruption in the job market, I don't think there would have been much more than a short term disruption in the OEM business.
http://www.npr.org/templates/story/story.php?storyId=9784361...
https://www.youtube.com/watch?v=poM423pewRE - “the home way”
https://www.loupe-magnifier.com/tungsten_finger_ring_removal... - “the professional way"
If you drop an endmill (like a drill bit but different, about the size of your thumb) from a normal carrying height to a concrete floor, you'll almost certainly be buying a new endmill; much like dropped buttered toast always seems to land butter side down, a dropped end mill always seems to land point down and crack a big chip off. A ring should be lighter so less stress, and smooth would imply no stress concentration points, but I'd still be careful about impacts or dropping it.
Another anecdote is interrupted cuts on a metal lathe will shatter carbide seemingly instantly every time, you need to use "old fashioned" high speed steel to cut anything with a gap. I wonder if the vibration of taking a diamond tip engraver to a carbide ring would shatter the ring instantly.
An interesting anecdote is a rather large lump of carbide for a replaceable indexable cutter is a couple bucks and a rod of carbide turned into a polished sharpened precision endmill of a large size is only maybe $30. Possibly the ring could cost more because that specific type of carbide looks very nice or has been stress relieved or annealed somehow to make it less brittle, and of course there's the labor time of a professional jeweler if its custom work. But the raw material, unlike gold or Pt, can't cost more than perhaps $100 for a carbide ring.
Not really. It's a ceramic and as such will shatter if knocked against another ceramic, hardness notwithstanding. Also, for some reason, my skin eats away at it.
See my tungsten carbide ring vs my fiance's ring (mine is on the left) - both made before the requirement that the rings come with break points built-in - https://i.imgur.com/fSIOUJf.jpg
Note the differences - his ring looks brand new. Both rings bought at the same time, same maker, same style.
Mine's practically obliterated.
Toughness is what determines energy before breaking and note that while many ceramics are not at all tough, high end technical ceramics are tougher than most metals[1]. High quality WC is indeed tougher than steels. It's also twice as strong as most steel, but high-end steels surpass it in strength.
[1]: http://www.cam.ac.uk/sites/www.cam.ac.uk/files/news/research...
With ceramics and glass, things get a little tricky. You can take a relatively weak and softer piece of pottery ceramic and obliterate the hardened bullet-resistant windows on police cars (the laminate inbetween being a different matter, but the glass itself will shatter/crack.) That happens via ultrasonic frequencies created on impact.
All of that is wrong. You can't use pottery shards or even hard pebbles to break glass; you need very hard technical ceramics[1]. Spark plug ceramic is alumina which is extremely hard.
It has nothing to do with ultrasonic frequencies, it's caused by crack propagation. Tempered glass is under internal stress due to its quench rate and chemical treatment, so as soon as the outer shell is broken the entire thing shatters. Alumina is so hard that a corner can chip off a bit of glass, releasing that pressure.
Ceramics can't be tempered like glass, and like untempered glass they only shatter if an impact by a much harder object is above the fracture propagation energy. That means that most of the time the impact energy is about the same as the actual toughness of the material. For high toughness ceramics there are no materials hard enough to cause chipping, so they break exclusively under normal toughness.
[1]: https://en.wikipedia.org/wiki/Ninja_rocks
Plenty of pottery contains aluminum oxide, which is very hard.
Alumina will effortlessly scratch gorilla glass, any metal, tungsten carbide and even a lot of sapphire glass. No kind of pottery will do any of those things.
Coal dust will abrade and destroy almost everything and it's because of the graphite, not the diamond. I have a coal mine. It's killed two phones and a drone already.
"Alumina will effortlessly scratch gorilla glass, any metal, tungsten carbide and even a lot of sapphire glass. No kind of pottery will do any of those things."
This is entirely untrue, it depends on the composition of the clay used in making the ceramic, which will be entirely dependent upon the location the clay or clay mix is obtained from. I also happen to do lapidary and pottery work, as a profession (next to LED lighting applications.) You can get clay from Mt. Baldy, make pottery, fire it up, it will scratch the hell out of almost everything because of the sand grain-sized rubies contained within.
if you ever get into trouble it'll be your finger that comes off, not it.
Tungsten carbide slugs: https://www.youtube.com/watch?v=UDWD4VM-31E
Shooting a tungsten cube: https://www.youtube.com/watch?v=n5kEj5ijChc
etc.etc.
Tungsten will strip out any barrel, even normal copper jacketed bullets can strip a barrel after a few 1000's of rounds.
Some calibers are prone to stripping more than others which is why some high end rounds will be covered by a polymer coating that adds lubricity and protects the barrel (it also has the benefit of dampening some inconsistencies in the barrel itself which can improve precision).
Tungsten given enough velocity will go through pretty much anything, this isn't something you want with bullets both because you usually do not want bullets to go beyond their targets and that a bullet needs to be able to dump it's energy into the body to be effective.
Small caliber through and throughs leave much less tissue damage unless hitting a vital organ and even then a larger, slower round that deforms would transfer more energy to the target.
The velocity of the bullet has a hard limit and that is the energy that is stored in the chemical propellant.
As for missiles tungsten is heavy as fuck, it's denser than Uranium and Lead you want your missiles to have as long of a range as possible, be as fast as possible (to be harder to intercept) for that you need them to be as light as possible. If you can make your missiles take on more weight and you've already achieved the desired range and velocity then you better off just putting more stuff that goes boom than an inert metal that does nothing.
Tungsten, just like high carbon steel and depleted uranium is useful for only one thing and that is penetrating armor, in those cases you would optimize your penetrator for that task meaning you'll be using a small narrow profile (basically a dart, or well a flechette) which moves really fast and can compromise heavy armor.
The only real use for tungsten in traditional projectiles it to defeat composite reactive armor that would make shaped charges and other traditional anti armor munitions less or completely in effective.
Even in those cases the tungsten penetrator is more often used to either disable the vehicle by destroying it's engine block, turret controls, suspension and tracks or by compromising the main body armor and then finishing it off with a explosive anti armor around that would also cause crew casualties (in a war of attrition killing the tank crew is often more important than destroying the tank).
It's also important to note that tungsten penetrators are often not made out of pure tungsten since it blunts (relatively) easily, so carbides and other really hard materials would be used to make it even more effective.
Besides that Tungsten might be useful for gravity penetrators basically "bunker busters" although in that case DU and lead might be just as potent unless you are limited by the size of the bomb itself.
Lastly the only other real use of Tungsten is in DIME warheads, these warheads employ inert metal powder as the force delivery mechanism, they fill their effective area with micro-shrapnel that pretty much would tear and liquify all tissue within it's blast radius but due to the high density of the metal and the limited explosive charge have a very small blast radius for intended lethal zone reducing direct collateral damage to zero.
I'd guess this can be prevented by using a tungsten core surrounded by a copper jacket, or an exposed tip as in m855a1
Strange that the article didn't mention who was first to field tungsten AP ammunition - it was the Luftwaffe
Edit: I didn't mean to imply m855a1 contains tungsten, rather that a similar design could prevent excessive barrel wear
The M855A1 is also lighter than the M855 so if my memory serves me correctly they've switched to a mild steel core.
The M955 does use a tungsten carbide penetrator and is classified as an AP round but the usual "green tip" (or well just "green" ammo now since the A1 doesn't have a tip color) ammo that is in use uses steel penetrators for the most part.
http://www.cabelas.com/product/Non-Toxic-Shot-Buyers-Guide/5...
Not sure they saved themselves a lot of money, copper is $. I knew they were trying a tin alloy at one point, not sure what happened to that other than Google saying "Unstable at high temperatures", which is interesting.
Tungsten ended up being just as toxic ( The round also had stability and terminal ballistics issues but that is another topic) as lead so they've replaced that one in the M855A1 with mild steel.
Then they had a fancy jacket made out of bismuth and tin alloy that appeared to be both not exactly environmentally friendly especially for the users due to buildup of bismuth salts firearm and unstable at high temperatures which causes inconsistencies in accuracy when fired from a hot barrel.
So they've pretty much moved back to a copper alloy half jacket and an arrowhead steel tip insert, the M855A1 also didn't solve all balsitis issues and ended up being slightly longer which can cause feeding issues.
Most of my barrels are ferritic nitrocarburized, so they should be impervious to anything... guessing that the US armed forces might have as fancy bore linings.
And don't be surprised if military guns are less decked out than yours they are built to costs.
Also remember that it's how often you clean your barrel and how many rounds you fire.
The M855A1 was designed to used in both assault rifles and LMGs so something like a SAW would fire 1000s of rounds before it can be properly cleaned up. Even an M4 would probably be much less cared for while on active duty than your match grade rifle.
A quick search suggests M16/4 barrels are chrome lined - just like a good AK
It's also self-sharpening (ie rather than smooshing like plastic on contact, parts break off and leave a sharp edge behind like flint), and because it's effectively subsidized by power generation and the nuclear program it's extremely cheap compared to Tungsten. Tungsten alloys are tougher[1] (actually, some of the toughest materials period) but penetration depends heavily on the armor type.
Hell, tungsten is toxic too and the military's biggest motivation is probably just as a really effective PR move. Uranium is definitely worse though, and I'm glad the US doesn't use it in munitions much. Uranium forms oxides that are very bioavailable (and even absorbed as gas through the lungs), and are really bad for you and even worse if you get pregnant.
[1]: http://www.cam.ac.uk/sites/www.cam.ac.uk/files/news/research...
Isn't drag essentially quadratic to speed? Isn't needed input energy also quadratic to speed, while momentum is linear to both mass and speed? Hardness aside don't you have much harder hitting bullets with these heavy elements?
> Hardness aside don't you have much harder hitting bullets with these heavy elements?
Maybe I'm tired but I can't parse this question.