Sunday, 19 February 2012

Sapphire Fusion - "Experiments at + 2000°C"

Sapphire (Greek: sappheiros, "blue stone") is a gemstone variety of the mineral corundum, an aluminium oxide (α-Al2O3). Trace amounts of other elements such as iron, titanium, or chromium can give corundum blue, yellow, pink, purple, orange, or greenish color. Chromium impurities in corundum yield a red tint, and the resultant gemstone is called a ruby. They can also be manufactured for industrial or decorative purposes in large crystal boules. Because of the remarkable hardness of sapphires (and of aluminum oxide in general), sapphires are used in some non-ornamental applications, including infrared optical components, such as in scientific instruments; high-durability windows (also used in scientific instruments); wristwatch crystals and movement bearings.
Synthetic sapphire is industrially produced from agglomerated aluminum oxide, sintered and fused in an inert atmosphere (hot isostatic pressing for example), yielding a transparent polycrystalline product, slightly porous, or with more traditional methods such as Verneuil, Czochralski, flux method, etc., yielding a single crystal sapphire material which is non-porous and should be relieved of its internal stress. The melting point of sythetic sapphire is 2050°C.
First time for decorative Purpose
In the past months Angular Momentum has made some experiments fusing sapphire of various colors on a transparent sapphire watch crystal or dial. The process can be compared to classic virtreous enamel where glass powder is fused to a supstrate like gold, silver or copper with temperatures between 750 and 850 °C. But since the melting point of sapphire is 2050°C it is neither possible to fuse it with metal substrate nor using thin wires which are applied to form raised barriers, which contain different areas of subsequently applied enamel used in Cloisonné
The "Fusion" timepieces are showing some humble but still enchanting results of the first experiments.


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