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Cer-vit is a family of glass-ceramic materials that were invented by Owens Illinois in the mid-1960s. Its principle ingredients are the oxides of
lithium Lithium (from , , ) is a chemical element; it has chemical symbol, symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard temperature and pressure, standard conditions, it is the least dense metal and the ...
,
aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...
and
silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...
. It is melted to form a glass which is then heat treated to nucleate and crystallize it into a material that is more than 90% microscopic crystals. Its formulation and heat treatment can be modified to produce a variety of material properties. One form is a material that is transparent and has a near zero thermal expansion. Its transparency is because the microscopic crystals are smaller than the wave length of light and are transparent, and its low thermal expansion is because they have a spodumene structure. Cer-Vit C 101 was used to form large mirror blanks ( in diameter) that were used in telescopes in several places, including South America, France and Australia. Owens Illinois ceased production of C101 in 1978. In addition, Cer-Vit materials were used to make stove tops, cook ware and aviation applications, but never commercialized. Today, glass-ceramic products such as transparent mirror blanks and stove tops, and cookware are manufactured and in daily use. These products include trade names of Zerodor, Hercuvit, and Pyroceram, most of which have low or zero thermal expansion, which allows them to be exposed to rapid temperature changes or localized heating or cooling.


Applications

At
Mount Lemmon Observatory Mount Lemmon Observatory (MLO), also known as the Mount Lemmon Infrared Observatory, is an astronomy, astronomical observatory located on Mount Lemmon in the Santa Catalina Mountains approximately northeast of Tucson, Arizona, Tucson, Arizona (U ...
, two 1.5 meter diameter telescopes have a Cer-Vit glass mirror. One of the telescopes discovered 2011 AG5, an asteroid which achieved 1 on the
Torino Scale The Torino scale is a method for categorizing the impact hazard associated with near-Earth objects (NEOs) such as asteroids and comets. It is intended as a communication tool for astronomers and the public to assess the seriousness of collision p ...
.


References


Bibliography

* Structure and Characterization of Lithiumaluminalsilicate Glass and Glass Ceramics derived from Spodumene Mineral. A. Nordman, Y Cheng, T.J. Bastock, Journal of Physics Condensed Matter, Volume 7, Number 16 * Glass-ceramics capture $2 million telescope-mirror contract. David H. Taeler, Ceramic Age, August 1968, Volume 84, Number 8 * Transparent Glass-Ceramics G. H. Beal, D. A. Duke, Journal of Materials Science 4(1969) 140-152


External links


Glass Types - Oldham OpticalLow thermal expansion glass ceramics - Hans Bach, Dieter Krause
Glass types Glass-ceramics Low-expansion glass Glass trademarks and brands Transparent materials {{optics-stub