Using hydrogen as a knife

In the high heat of a gold-plated oven, the injected ions form hydrogen bubbles that cause the sapphire wafer (at right side of black platform) to slough off a thin layer of sapphire (at center of platform). Credit: GT Advanced Technology

The recent Apple Watch announcement has tickled my interest on “sapphire”. This material is particularly hard (in a chemical - physical sense), 3 times as resistant to scratches than the best hardened glass and just a bit “softer” than diamond. Apple has acquired a company in Arizona for 700 Ml$ manufacturing sapphire.

The problem with diamond is that it is very expensive and the problem with sapphire is that it is quite expensive, 5 to 10 times more than hardened glass.

Finding a way to produce it in a more economical way would allow its use in a broader sets of products, like cellphones and tablet screens.

Here comes the news of a company in Massachusetts, GT Advanced Technologies, that have found a way to exfoliate layers of sapphire at a sustainable cost and then gluing them onto a normal slab of glass making its surface as hard and resistant as if it were a solid sapphire screen.

The process they have developed is quite interesting, and amazing to a person like me that is not familiar with these technologies.

They take a slab of sapphire about a millimetre thick and subject it to a bombardment of hydrogen ions (protons) accelerated by a machine in a 20 Million V field. The strength of the bombardment can be finely tuned and the higher the impact energy to deeper the ions go under the surface. They have trimmed the field (20 MV) to get a penetration of 0.1 mm. This creates a layer of ions that basically separate the surface of the sapphire from the slab resulting in a 0.1 mm thick layer. This layer is then glued onto a glass slab giving it the desired resistance.

I find this an amazing result. 
They expect to be able to move into mass industrial production in 2015. For that, the missing part is a way to automatically transport the sapphire exfoliated from the slab to the glass and glue it.

Author - Roberto Saracco

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