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Breakthough Makes Transparent Aluminum Affordable
frank249 writes: In the Star Trek universe, transparent aluminum is used in various fittings in starships, including exterior ship portals and windows. In real life, Aluminium oxynitride is a form of ceramic whose properties are similar to those of the fictional substance seen in Star Trek. It has a hardness of 7.7 Mohs and was patented in 1980. It has military applications as bullet-resistant armor, but is too expensive for widespread use.
Now, there has been a major breakthrough in materials science. After decades of research and development, the U.S. Naval Research Laboratory has created a transparent, bulletproof material that can be molded into virtually any shape. This material, known as Spinel (magnesium aluminate), is made from a synthetic powdered clay that is heated and pressed under vacuum into transparent sheets. Spinel weighs just a fraction of a modern bulletproof pane.
Now, there has been a major breakthrough in materials science. After decades of research and development, the U.S. Naval Research Laboratory has created a transparent, bulletproof material that can be molded into virtually any shape. This material, known as Spinel (magnesium aluminate), is made from a synthetic powdered clay that is heated and pressed under vacuum into transparent sheets. Spinel weighs just a fraction of a modern bulletproof pane.
Before we ask for this for windshields, we need to see how well it handles regular abrasive friction and small particulates. If it scratches easily then it may require a coating of glass on either side for its hardness (albeit with brittleness) in cases where security needs to go along with aesthetics, like armored car windows and other security windows, such that the owners don't care what happens to the glass layer in an incident but want it to look good before the incident and to remain intact during such incidents.
I doubt that this will be, by itself, a windshield, and if a windshield made out of this stuff still needs a glass layer, then you're right back to where you were before as far as chipping with debris over a certain size is concerned.
Do not look into laser with remaining eye.
I thought they didn't MAKE transparent aluminum in Star Trek IV, Scotty provided the formula as an incentive to provide plexiglass panels for free (since they had no 1980s cash).
The tank wasn't made from transparent alumin(i)um. Scotty traded the formula for enough polycarbonate sheets to build the tank. IIRC they even say it will take years of research to manufacture the stuff.
</pedant>
(mind you, they still could have done the job more cheaply with steel, or welded some deck plates together, or simply filled a cargo bay with water. But it made for a good scene, and who cares?)
How can I believe you when you tell me what I don't want to hear?
Spinel has 7.5-8 on the Mohs scale, should it should be *more* scratch resistant than glass.
It's harder than quartz. Says so right in the summary, Mohs scale of 7.7. Glass is in the middle somewhere, depends on the type of glass. Gorilla glass is apparently around 6.5
Great answer, except for the Kevlar part. Safety glass and "bulletproof" glass already work this way, except you don't use Kevlar. You use plastic, not sure what type.
The plastic creates a discontinuity in the glassy material. If the hard but brittle glass shatters, the shatter lines stop at a plastic layer (in really fancy systems you have multiple layers). The plastic also helps hold the material together under failure conditions, reducing shrapnel wounds at time of impact and danger to bystanders afterwards.
The layering concept has wide applicability. There are reports of high end tank armour using layered ceramics and steel going back to the 1970's.
> One of the features of safety glass is that when it breaks there aren't (or many) pointy edges created.
Which kind of safety glass?
They were talking about windshields, those are laminated glass. That means you have two sheets of ordinary annealed glass (which DOES break into big, dagger-like sharp pieces) with a plastic sheet in between (which prevents those sharp pieces from going anywhere). Presumably, given an appropriate substrate, you could make laminate out of any glass-like sheet.
The other kind of safety glass is tempered. This causes the glass to be stressed along the edges so that when it does break, it breaks into a million tiny pieces (all of which are very, very sharp). It may also simultaneously pop, especially if hit along the edges. It's less dangerous because the pieces, while sharp, are simply too small to do any real damage even if, say, a piece explodes while you're holding it.
Source: I worked for a cut & temper operation, I've dealt with all kinds of glass.
It doesn't shatter easily because it's a sintered polycrystalline. Rather than being like the single grown sapphire crystals that Apple rejected for the iPhone which shatter easily along crystal fault lines, it's lots of crystals all jumbled together. Crack propagation doesn't happen so much. According to TFA, it chips, but it doesn't shatter.