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Star Trek Fans!!!!! Transparent Aluminum is finally here!
    #3040410 - 08/23/04 07:10 PM (12 years, 7 months ago)

what a world we live in!


http://physicsweb.org/article/news/8/8/9

Glass breakthrough
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 1000?C. 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


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Offlinecb9fl
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Re: Star Trek Fans!!!!! Transparent Aluminum is finally here [Re: blink]
    #3040622 - 08/23/04 08:08 PM (12 years, 7 months ago)

Helloooo Computer.


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InvisibleEdame
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Re: Star Trek Fans!!!!! Transparent Aluminum is finally here [Re: blink]
    #3045119 - 08/24/04 06:42 PM (12 years, 7 months ago)

I saw this posted on Slashdot, but it should be noted that the claims that this is transparent aluminium appear to be misleading. The article refers to Alumina which is aluminium oxide, it has more in common with gemstones like Ruby and Sapphire than metal.


--------------------
The above is an extract from my fictional novel, "The random postings of Edame".
:tongue:

In the beginning was the word. And man could not handle the word, and the hearing of the word, and he asked God to take away his ears so that he might live in peace without having to hear words which might upset his equinamity or corrupt the unblemished purity of his conscience.

And God, hearing this desperate plea from His creation, wrinkled His mighty brow for a moment and then leaned down toward man, beckoning that he should come close so as to hear all that was about to be revealed to him.

"Fuck you," He whispered, and frowned upon the pathetic supplicant before retreating to His heavens.


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OfflineKrazieH8er
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Registered: 11/08/03
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Re: Star Trek Fans!!!!! Transparent Aluminum is finally here [Re: Edame]
    #3046568 - 08/25/04 12:24 AM (12 years, 7 months ago)

This is truly amazing. I would like to buy a transparent bycicle.


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OfflineRuNE
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Re: Star Trek Fans!!!!! Transparent Aluminum is finally here! [Re: blink]
    #3049791 - 08/25/04 08:08 PM (12 years, 7 months ago)



Cool.  :thumbup:

I wonder what uses they'll have for this.



:sun:


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~Happy sailing~


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