Transparent Alumina - (aluminum oxide) Three Times Stronger Than Steel

www.rense.com ^ | 2-25-02

[Husker24]

Maybe they can make an invisible tank out of this stuff.

[Bloody Sam Roberts]

Do they run without water cooling?

I don't know. I sure would love to be able to tell you from personal experiaence. Those STS's are so sweet.

It bears investigating.

[Bloody Sam Roberts]

experiaence=experience

[RightWinger]

Cool . . . I have $45K of ALCOA stock.
If and when ALCOA perfects the ceramic anode, the stock price will skyrocket!

[Tench_Coxe]

An Apple.

[Bernard Marx]

Transparent alumina (corundum, var. sapphire) has been around for years and years -- better quality watch crystals are made from it. I went to the site LarryLied provided in #47 above and am more confused than ever. All I can deduce is that they have developed a means of bonding smaller segments of the material together and have developed better methods of fabricating new shapes and polishing. The hardness vs. toughness aspect has me puzzled and it isn't explained as far as I can tell. As a ceramic, synthetic corundum shatters easily even though its hardness is 9 on Mohs' scale, next to diamond (even though diamond is about 40 times as hard as corundum!) The article doesn't mention what kind of material is used to bond the smaller segments, nor does it explain how it has been changed to have the toughness for the things they plan to use it for. Maybe we missed something in the translation?

[blam]

"helloooo computer..."

Yup. I made an experimental on-chip by-pass capicator about ten years ago using al ox. (The secret was in the method of oxidation)

[dvwjr]

Does this mean that the tin-foil hat crowd can now go about in public fully equipped while still appearing normal??? They will seem to be both sane and clear-headed.... hmmmm.

[spunkets]

The mat'l here is microcrystalline Al₂O₃. The xtal structure of the micro domains is the hexagonal corundum structure, but the order doesn't extend beyond, say 10 angstroms at most. That's why it's transparent. The normal opaque white of sintered ceramic is diffusion of light by multiple refraction from each of the crystalites in the sintered piece. Those are very large compared to these. In this stuff the crystallites are so small the light path is not changed significantly by passing through any of the crystallites, the total effect is a slight haze as seen in the pic. What they did was form essentially a glass melt and cooled it quickly enough to freeze in the roughly glass structure. It was then tempered to relieve stress. The toughness comes from the extremely large number of paths a crack can take, none of which tend to fall along what is essentially a linear path along grain boundaries. Lattice distortions between microcrystallites are also possible in the glassy areas. ie. It behaves as a 2 component composite of amt'ls with the same refractive index.

[mdittmar]

Thats what I hope,I'm tired of all those nasty comments.

[Doctor Stochastic]

"Are you copper-bottoming 'em, my man?"

No, I'm aluminiuming 'em, mum."

[thrcanbonly1]

It would make some nifty beer cans . . . .

Never butt your smoke in a full can again!

[Newbomb Turk]

Unobtanium is manufactured at this same lab. Ever seen any ? It's cool stuff.

[LarryLied]

What they did was form essentially a glass melt and cooled it quickly enough to freeze in the roughly glass structure.

Aha!...similar to how they make super hard steel. Freeze the melt fast and you get a non-crystalline metallic glass.

[apochromat]

It appears to have an even absorption spectrum, and it's slightly diffusive. In other words, it's "milky".

[Bernard Marx]

Thanks for your explanation, Spunkets. I can think of a few good uses for this material beyond those already mentioned.

[tjg]

Actually, in metallurgy, toughness is a measure of a materials ability to resist brittle fracture.

But I don't think the author really meant toughness in that way.

What you are asking is how far will it bend before it breaks. It's an excellent question and the answer will determine the simple question; is it as usefull as steel?