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Transparent Aluminum Is Here
Posted by
Hemos
on Mon Aug 23, 2004 09:09 AM
from the like-blue-LEDs dept.
from the like-blue-LEDs dept.
Alien54 writes "Scientists in the US have developed a novel technique to make bulk quantities of glass from alumina for the first time. (link includes a picture of samples) Anatoly Rosenflanz and colleagues at 3M in Minnesota used a "flame-spray" technique to alloy alumina (aluminium oxide) with rare-earth metal oxides to produce strong glass with good optical properties. The method avoids many of the problems encountered in conventional glass forming and could, say the team, be extended to other oxides (see also: A Rosenflanz et al. 2004 Nature 430 761). Scotty would be pleased."
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Scotty would be pleased. (Score:5, Funny)
Re:Scotty would be pleased. (Score:5, Funny)
Parent
Re:Scotty would be pleased. (Score:5, Funny)
Oh, a keyboard, how quaint.
!
Parent
Re:Scotty would be pleased. (Score:5, Funny)
You mean 18! (or are you posting to Slashdot... from the future! (*GASP!*))
Parent
Re:Scotty would be pleased. (Score:5, Funny)
I'll lay odds a burly guy with a dodgy scottish brogue was around their head office trying to use a mouse as a dictaphone not too long ago....
Regards
Luke
Parent
Re:Scotty would be pleased. (Score:5, Funny)
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Re:Scotty would be pleased. (Score:5, Funny)
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Re:Scotty would be pleased. (Score:5, Funny)
(The amusing part about that statement is that the Russian language has no 'W' sound!)
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Re:Scotty would be pleased. (Score:5, Interesting)
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Re:Scotty would be pleased. (Score:5, Funny)
Parent
Never understood that. (Score:5, Funny)
Presumably he had a run of bad tea-machine experiences like this:
"Tea, Earl Grey." <sip> "Awww fuck my old boots, it's half-cold and stewed you fucker"
Parent
I sence a great disterbence in the force.. (Score:5, Funny)
Parent
Re:Scotty would be pleased. (Score:5, Funny)
"A Windows Key. How quaint!"
A Windows Key? On a Mac?!?
Parent
Re:Scotty would be pleased. (Score:5, Funny)
7) Jokes usually need a grain of truth or a plausible premise in order to be funny.
e.g. "3 girls jumped off a building. Which one hits last? The one who stopped to ask for directions!"
That's not funny because it's a ridiculous situation with no roots in reality. On the other hand,
"A Blonde, a Brunette, and a Red Head all jump off a building. Which one hits last? The Blond! She had to stop and ask for directions!"
That is funny because the premise for the joke is a commonly held belief that blonds are dumb. Of course, such suppositions are often flawed and allow for an equally amusing joke that makes the exact counter point:
"So a Blond walks into a bank and asks for a two week loan of $10,000. Dubious of the Blond's motives, the bank manager asks for collateral. The Blond replies that she could always put her Mercedes up as collateral, since it was worth far more than her loan. The bank manager agrees, and drives her car into the bank garage after loaning her the money.
"In two weeks the Blonde returns with the $10,000, plus the $5.00 interest on the loan. As the manager returns the keys to her car, he asks, 'I did some checking while you were away. It seems you're loaded with money! Why did you need a loan for two weeks?' To which the Blonde replies, 'Where else in New York can I park my car for two weeks and only pay $5.00!'"
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woohho (Score:5, Funny)
Re:woohho (Score:5, Insightful)
Parent
Re:woohho (Score:5, Insightful)
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Re:woohho (Score:5, Funny)
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Re:woohho (Score:5, Informative)
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Re:woohho (Score:5, Interesting)
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Transparent aluminum foil (Score:5, Funny)
Re:Transparent aluminum foil (Score:5, Funny)
More importantly, I can wear my improved tinfoil hat in public without getting weird looks.
Parent
Re:Transparent aluminum foil (Score:5, Funny)
Like, duh!
Paranoid kook n00b
Parent
Article text, for the slashdotted (Score:5, Informative)
11 August 2004
Scientists in the US have developed a novel technique to make bulk quantities of glass from alumina for the first time. Anatoly Rosenflanz and colleagues at 3M in Minnesota used a "flame-spray" technique to alloy alumina (aluminium oxide) with rare-earth metal oxides to produce strong glass with good optical properties. The method avoids many of the problems encountered in conventional glass forming and could, say the team, be extended to other oxides (A Rosenflanz et al. 2004 Nature 430 761).
Glass is formed when a molten material is cooled so quickly that its constituent atoms do not have time to align themselves into an ordered lattice. However, it is difficult to make glasses from most materials because they need to be cooled -- or quenched -- at rates of up to 10 million degrees per second.
Silica is widely used in glass-making because the quenching rates are much lower, but researchers would like to make glass from alumina as well because of its superior mechanical and optical properties. Alumina can form glass if it is alloyed with calcium or rare-earth oxides, but the required quenching rate can be as high as 1000 degrees per second, which makes it difficult to produce bulk quantities.
Rosenflanz and colleagues started by mixing around 80 mole % of powdered alumina with various rare-earth oxide powders -- including lanthanum, gadolinium and yttrium oxides. Next, they fed the powders into a high-temperature hydrogen-oxygen flame to produce molten particles that were then quenched in water. The resulting glass beads, which were less than 140 microns across, were then heat-treated -- or sintered -- at around 1000C. This produced bulk glass samples in which nanocrystalline alumina-rich phases were dispersed throughout a glassy matrix. The new method avoids the need to apply pressures of 1 gigapascal or more, as is required in existing techniques.
Click to enlarge
Aluminate glasses
The 3M scientists characterised the glasses using optical microscopy, scanning electron microscopy, X-ray diffraction and thermal analysis, and tested the strength of the materials with hardness and fracture toughness tests. They found that their samples were much harder than conventional silica-based glasses and were almost as hard as pure polycrystalline alumina.
Moreover, over 95% of the glasses were transparent (see figure) and had attractive optical properties. For example, fully crystallized alumina-rare earth oxide ceramics showed high refractive indices if the grains were kept below a certain size.
Author
Belle Dumé is Science Writer at PhysicsWeb
Silly submitter (Score:5, Insightful)
What next, suggesting people use the silicon [wikipedia.org] in their computers as a breast implant [wikipedia.org]?
Why not link to... (Score:5, Informative)
Parent
Re:Submitter - Not Silly (Score:5, Informative)
As I understand it, pure metals can't be transparent because light is an electromagnetic wave which gets "short-circuited" by conductive materials. Presumably the oxides disrupt this conductivity. And anyway, the alumina is combined with other oxides before being used to form glass.
Parent
Re:Submitter - Not Silly (Score:5, Informative)
Sort of....
A better way of explaining it would be that for a photon to be absorbed by an electron, there must be an empty higher energy state for the electron to move to (E = Eo + hv, where Eo is the energy state of the electron and hv is the energy of the photon). In solids with metallic bonding, there are many electrons floating around and many free electronic states for them to move to, so any photon that enters the solid can be absorbed by an electron that will then jump to a higher energy state (which will be free, because there are so many free energy states).
In the case of insulating and semiconducting materials, there is a gap in the energy states, so some transitions are not allowed. For pure, single crystal Al2O3, (aka white sapphire), there are (essentially) no transitions available that correspond to the energy of photons of visible light. If you start substituting in Cr3+ ions for the Al3+ ions, your sapphire will turn red and we call it "ruby". In this case, the Cr impurities provide transitions that can absorb wide ranges of visible light, but not red light. What is more is (if this is fairly pure), the ruby will not only absorb light of other wavelengths, but it will emit red light as well. Try putting a synthetic ruby under a UV light, it will glow red.
However, it should be noted that other defects can scatter and absorb light as well. Grain boundaries, voids, inclusions, etc. will affect your light transmittance. It has been possible for some time now to make polycrystalline alumina that is translucent (Lucalox), but polycrystalline alumina can never be transparant, so there are two ways to make alumina transparant: make it single crystal (only one grain, so no grain boundaries) or amorphous (no grain boundaries, because there is no long range crystal order).
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Re:Submitter - Not Silly (Score:5, Informative)
Therefore, the term "transparent aluminum" is incorrect. Sorry.
Parent
well then there are rubies and stuff (Score:5, Informative)
google search of rubies and aluminum:
http://pearl1.lanl.gov/periodic/elemen
It's not aluminum, it's alumina. (Score:5, Informative)
Alumina or corundum [mindat.org] as the natural material is known, is found in nature as a clear mineral - different colour variations give you Ruby and Sapphire.
Jolyon
Re:It's not aluminum, it's alumina. (Score:5, Funny)
I mean, after the tiger-repelling rock, I thought i learned not to misunderestimate science!
Parent
science inspiring sci-fi inspiring science... (Score:5, Interesting)
I remember an interview with James Doohan where he said his greatest pride that came from his career was that he inspired other people to pursue careers where they could make a difference to the world. How many engineers became engineers or went into sciences because of Star Trek?
I'm familiar with the Arthur C Clarke suggesting satellites; I doubt a similar cause/effect with Star Trek IV happened here. However, the similarities are cool, and at least with this genre there is the POSSIBILITY of changing the world for the better.
PS Fortunately such transitions from sci-fi fantasy to real world are few and far between. 90%+ of tv SF and pulp SF is dreck, and I myself and not looking forward to a Brave New World...
Transparent ALUMINA (Score:5, Informative)
And hard is only one part of the story. Glass is hard, yet I wouldn't want to make structural elements of an aircraft from large hunks of glass... Aluminum is light and Tough (high energy to break). It is also ductile (deforms before breaking) something that no ceramic is...
So, while this is cool, and will probably be used for super scratch proof layers on spyplane camera transparencies or something like that where they can afford something like this, it isn't what you think it is.
As an aside, translucent alumina is used in something you see everyday - sodium vapor lamps use alumina to encapsulate the sodium metal that they use as their filament.
purdy pieces! (Score:5, Funny)
RTFA Editors (Score:5, Informative)
Transparent Aluminum Is Here
NO IT ISN'T! Commercially developed transparent Alumina (think clear ruby/sapphire) is here, HUGE difference. Sorry Trek fans, you will have to wait longer. There will be no clear planes, no clear cases made of Alumina. If cases were transparent Alumina then they would have the same properties as silica glass and you would have a nice greenhouse effect going on slowly (or not so slowly) frying your computer.
Alumina is a mineral/glass/ceramic, Aluminum is a metal!
PowerBook (Score:5, Funny)
Somehow, I get the feeling that Apple is going to use this for the next gen of PowerBooks.
(It's a joke -- all the materials scientists don't need to correct me.)
-"Zow"
Transparent Alumina (Score:5, Informative)
If you have a high quality watch it is likely that the crystal is made from polycrystalline alumina (i.e. corundum...in this case synthetic corundum). The alumina glass is different however in the fact that it is a glass and therefore lacks crystal structure.
Since it doesn't have to be crystallized it is likely that it will be able to be produced in large sizes. However, being a glass it is not going to have the malleable properties of aluminum metal and will probably shatter if hit hard enough.
"Making large sheets of ruby and sapphires" (Score:5, Funny)
I'd love a pair of sapphire-lensed sunglasses.
Sounds like a good plan for optical disks (Score:5, Insightful)
If that was the case, that would be an AWESOME application for this. Although the MP/RIAA would see that as a reason for preventing backup copies of your media. I mean, if the disk can't be damaged, why would you need a backup? Although you could still lose it or have it stolen...
Shouldn't we be doing something... constructive? (Score:5, Funny)
Re:Future echoes (Score:5, Funny)
Parent
Re:Future echoes (Score:5, Funny)
I like your list. But, what about the things we haven't invented yet?
Of course, I'm probably forgetting lots of stuff. Anyone have further things I've missed??
Parent
Re:Future echoes (Score:5, Funny)
Never been to a supermarket I presume?
Parent
Re:Future echoes (Score:5, Interesting)
Why more like radio?
My email is smart enough that if I start typing the first 2 or 3 letters of an email, it can guess at who I want to send it to and be accurate most of the time. I don't need to know the email addresses of anyone involved these days unless I don't have them in my address book which is sync'd between my phone, 2 PCs and 3 Macs. All work about the same.
So you don't dial a number, but you do say "Sulu, Can We Get A Fix On..." and the internal processing realizes that since he didn't refer to a specific Sulu, he must mean the default one and routes it appropriately.
My Cell is smart enough that if I hold a button on the side and say the name it can dial about a dozen numbers. Battery life and processing speeds preclude it from listening all the time.
So, are you saying that because our technology isn't very sufficient today, theirs too must be as unadvanced. I've seen attainable advancements in 10 years that make 20 years ago look like the stone ages. In another 10 years, maybe we will just speak into a phone, and it will wait until it figures out who we are talking too and route accordingly. Who knows. Maybe we will all be back to fighting wars with sticks and stones.
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Re:Future echoes (Score:5, Informative)
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Re:glassish properties (Score:5, Informative)
A common misconception caused by the old "spun" method of making glass which makes sheets which are thicker at the bottom than the top. People have often assumed that old glass has "flowed" into that shape. It hasn't: it was made that way. Glass does not in fact flow, not even slowly.
Search on Google for "glass flow" for lots and lots of stuff about this.
TWW
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Not Liquid (Score:5, Informative)
In general, the composition of glass makes a huge different in properties such as hardness, inertness, transparancy and color. In ordinary glass, CaO is added to lower solubility in water and various other solvents.
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Very, very, very slow (Score:5, Informative)
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No, it's an amorphous solid. (Score:5, Informative)
Seems a couple other people beat me to rebuking this, but I figured I'd throw another link in just in case there is any lingering doubt.
Glass is not a liquid. Glass is an amorphous solid. [tafkac.org]
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