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Roger Weller, geology instructor

by Juan DeLeon
Physical Geology
Spring 2016

                                Aluminum Oxynitride


     Aluminum Oxynitride is a ceramic composed of aluminum, oxygen and nitrogen.  It is more commonly known as aluminum glass. 


     Why Aluminum Oxynitride? Star Trek IV, to put it plainly, aluminum glass was used in the transportation of a couple of whales from the past to the future where they were extinct. When arriving in the past there were no resources to allow the crew to accomplish their mission so they had to help an engineer of that time to invent aluminum glass. The scene where the engineer from the future and the engineer of the present work together to create this new material is at the link below, for those of you that are nor sci-fi enthusiast.

     When this movie came out aluminum glass was already being developed, and had been so for at least five years prior. The mention and use of this material in the movie is something that Star Trek creators have done before, such as the flip phone, which can be traced to the communicators used by the crew.

Transparent aluminum starts out as a pile of white aluminum oxynitride powder. That powder gets packed into a rubber mold in the rough shape of the desired part, and subjected to a procedure called isostatic pressing, the process of isostatic pressing is when the mold is compressed in a tank of hydraulic fluid to 15,000 psi, which compacts the ALON into a grainy “green body.” The grainy structure is then fused together by heating at 2000 °C for several days. The surface of the resulting part is cloudy, and has to be mechanically polished to make it optically clear.

     It is marketed under the name ALON; ALON is optically transparent (≥80%). It is 4 times harder than fused silica glass, 85% as hard as sapphire which rates a 9 on the Mohs scale of hardness, and nearly 15% harder than magnesium aluminate.

     It can be fabricated for transparent windows, plates, domes, rods, tubes and other forms using conventional ceramic powder processing techniques. It may even one day be used to transport extinct animals through time and space.


     ALON is the hardest polycrystalline transparent ceramic available commercially. The combination of optical and mechanical properties makes this material a leading candidate for lightweight high-performance transparent armor applications such as bulletproof and blast-resistant windows and for many military infrared optics. ALON-based armor has been shown to stop multiple armor-piercing projectiles of up to 50 cal.

Below you will find a link to a video of Aluminum Oxynitride being tested in comparison with traditional bullet proof glass.

     Although this material is extremely useful and very strong, it is very expensive to produce. The cost of production limits the availability for use by the common consumer. So, if you have a desire to build a safe house, yet want a view aluminum glass is the way to go, if you can afford the cost.

Since the discovery of transparent aluminum ceramics in the early 1950s, many researchers have been involved in the study of transparent aluminum ceramics. Their work reports a number of challenges to be resolved for obtaining transparent aluminum ceramics with high transmittance rate, which includes the following:

Minimizing impurities

Eliminating micropores

Controlling grain boundaries.

As with all things maybe in the near future it will be readily available when a less expensive method of production is developed.

Works Cited


Royal Society of Chemistry, Periodic Table.
International Aluminum Institute. Web. 26 Apr. 2011
Aluminum, By Sam Davyson

Aluminium oxynitride–hexagonal boron nitride composites with anisotropic properties

Agnieszka Wilk, Paweł Rutkowski, Dariusz Zientara, Mirosław M. Bućko

Transparent Aluminum: Real, Glass-Like, See-Through Metal

Surmet's ALON® Transparent Armor 50 Caliber Test
The Wonders of Transparent Aluminum

By Sean Michael Ragan@seanragan, January 17, 2012, 1:00 pm PDT

Transparent Aluminum (Aluminum Oxynitride) – Properties, Production and Applications

By G.P. Thomas