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Transparent Aluminium
Lynx writes "As the german magazine Spiegel reports, scientists at the Fraunhofer Institute for Ceramic Technologies have developed a transparent tile made from aluminium oxide pellets baked at 1200C. The material is very hard, and could be used as bulletproof windows." Use the fish.
Ha! That guy finally figured out those equations Scotty gave to him back in Star Trek IV! Another technological breakthough thanks to good 'ol Scotty.
...with some transparent concrete to build a transparent house! Now people who want to live in a "glass" house don't have to worry about throwing things at each other! Oh, but they still have to worry about being naked...
Sorry. I should have read the blurb more carefully.
This isn't transparent aluminum; this is a transparent aluminum oxide. That is just not the same thing as aluminum anymore then water is Hydrogen gas, or table salt is the same thing as Sodium metal or Chlorine gas (both very harmful chemicals, sodium can explode when it comes in contact with water, and Chlorine can kill you in a few breaths, yet we eat salt all the time)
And secondly we have known about aluminum based compounds for a long time, in fact, longer then we have known about Aluminum or even about elements in general. Alum, the compound from which aluminum gets it's name (and which we extract aluminum from) has been known to man for ages and is, in fact, transparent.
autopr0n is like, down and stuff.
Btw, The artical indicates that this material is 3 times as strong as steal, making it far stronger then pure, regular, opaque, Aluminum metal.
autopr0n is like, down and stuff.
> this material is 3 times as strong as steal,
No, it says it is three times as _hard_ as hardened steel, which isn't the same thing (though they are related). Considering that corundum (i.e. ruby, sapphire) is made of aluminium oxide, that isn't that surprising.
Forming that hard material into tiles of unspecified but obviously reasonable toughness and strenth while keeping it transparent is the impressive bit.
rant
P.S. Considering the number of people who are confused about the difference between silicon and silicone, it's not surprising some can't tell the difference between aluminium and alumina (aluminium oxide).
(Aluminum/aluminium is just US/international spelling. Looking at the original German article it uses "Aluminiumoxid" where the fish translation has alumina.)
rant
let out a giant yawn.
Alumina being transparent or strong is hardly new. Although the bullet proof glass thing is pretty funny. Alumina is not tough, it may be strong, and even greatly stronger than steel should we be talking about specific strength, but it is not tough at all. And I don't know about you, but the last thing I was between me and a bullet is a sheet of something that will shatter with countless sharp edges to cut me to ribbons.
I'm sure there are a great many chemical concerns that would be thrilled to tell you all about their alumina powders should you care to ask. But trust me, until we can do with alumina what clams can do with chalk the most interesting thing one is likely to do with alumina is make a crucible.
--Jimmy has fancy plans; and pants to match.
as Babelfish & Co are not really up to it yet, here's my human-made translation of the German article. I'm a German native speaker, but I can't guarantee the English spelling, so take with a grain of salt ;-).
Things in [brackets] are my remarks.
- - - -
Der Spiegel [leading German magazine, a la Times or Newsweek]
February 19, 2002
TRANSPARENT
Armour-like tile protects from projectiles
Researchers in Dresden [German city] have developed transparent and extremely hard tiles. The Pentagon, among others, is fascinated by this material, which can be used to produce e.g. bullet-proof visors.
[PICTURE] picture caption: "transparent Aluminium tile"
America's weapon technicians show interest for an armour-like tile from Dresden. At the "Fraunhofer-Institut für Keramische Technologien" [Fraunhofer institute for ceramics technologies] there, fine-grained aluminium oxide was successfully baked in an oven at 1200 C to produce an extremely hard, transparent material.
A plate sized 10x10 cm (thickness: 1 cm) only weighs about 400 g, but is three times as hard as hardened [tempered?] steel. During shooting trials on behalf of the "Bundeswehrbeschaffungsamt" [federal procurement office] in Koblenz, "outstanding results" were achieved, according to the researcher Andreas Krell.
The tiles are also being examined in the US state of Idaho: The Pentagon is fascinated by the transparency of the material, which can be used to build bullet-proof visors or big windows for armoured personnel carriers [Panzerspähwagen?].
Unbreakable beer glass.
As an aficionado of German beer, I'm sure that this will be the first real application. They just want to get the military to pay for some cool toys along the way.
Strength - A property of materials under elastic deformation, meaning the degree to which the material bends under load, and then springs back to its original shape. At sufficiently high loading, the material deforms plastically, meaning it stays bent. Strong materials deflect very little under load (low strain per unit stress), and can take high loads before plastic deformation occurs.
Toughness - A property of materials that contain microcracks or other fracture-inducing characteristics. Such flaws cause localized increases in stress levels and thereby cause fractures to expand until the material fails catastrophically. This is the mechanism underlying stress-corrosion cracking and fretting fatigue. Tough materials do not have high localizes stress at crack tips, and can tolerate microcracks without catastrophic propagation and failure.
Hardness - The strength of a material at its surface. Measured empircally by poking it with sharp objects. Hard materials resist scratches and dents. But whether they deform (elastically or plastically) has nothing to do with their hardness. It has to do we their bulk strength.