
Transparent aluminum–from Star Trek to (almost) reality - jonbaer
https://ceramics.org/ceramic-tech-today/ceramic-video/video-transparent-aluminum-from-star-trek-to-reality
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ISL
I don't think it is pedantic to state that aluminum oxynitride is clearly not
aluminum.

This material, while it sounds super interesting is almost-certainly not a
metal.

Furthermore, among aluminum's key properties is its machineability. This stuff
sounds like it would destroy an end mill or shatter.

It is exceedingly difficult, if not impossible, to make a transparent metal.
If charge-carriers are free to move, a defining property of a metal, then they
will move in response to the electromagnetic field of a light wave. That
movement will act to either attenuate or reflect the light wave.

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Scaevolus
Aluminum Oxynitride was described before Star Trek IV's "transparent aluminum"
in 1986, so the suggested causative direction is backwards:

Hartnett, T. M., Maguire, E. A., Gentilman, R. L., Corbin, N. D. & McCauley,
J. W., Aluminum oxynitride spinel (ALON): A new optical and multimode window
material. Ceram. Eng. and Sci. Proe., 3(1-2) (1982) 67.

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supernova87a
Super interesting that they can now achieve an transparent quality with a
powder pressing technique.

And yes, the name is terrible. It's a composite material that contains
aluminum. Obviously it's not aluminum metal.

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pkaye
What is the difference between this and sapphire?

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xref
> Transparent aluminum, also known as aluminum oxynitride, is a transparent
> polycrystalline ceramic with a cubic spinel crystal structure made of
> nitrogen, oxygen and aluminum. It is optically transparent in the near-
> ultraviolet, visible and infrared regions. It is four times harder than
> fused silica glass, 85% harder than sapphire and 15% harder than magnesium
> aluminate spinel. The material remains solid up to 1200°C (2190°F). It has
> good corrosion resistance and resistance to damage from radiation and
> oxidation. It is about three times harder than steel of the same thickness.

[https://www.azom.com/article.aspx?ArticleID=8095](https://www.azom.com/article.aspx?ArticleID=8095)

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Tagbert
so.... not really aluminum, just another ceramic with a high aluminum content.

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xref
Article is upfront about it not being “elemental transparent aluminum” (a
distinction not made in the Star Trek movie I believe?) I mean, even aluminum
aircraft bodies are mostly alloys but we call it aluminum

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saagarjha
Alloys are most certainly metal, though.

