Cer-Vit
Encyclopedia
Cer-Vit aka CerVit or Cervit or Cer-Vit C-101 (from 'ceramic-vitreous'), is a glass-ceramic
material made up of oxides of silicon, aluminium and lithium, with ultra low coefficient of thermal expansion, used for telesope mirrors and lenses. It was made by Owens-Illinois
Corning
in 1967, and discontinued in 1978. Cer-Vit and Zerodur are two-phase ceramics consisting of a high percentage of crystalline silica-based material and the remainder of non-crystalline glass. These ceramics also include silica-based glasses such as Homosil fused quartz
, soda-lime glass
, and the like.
Glass-ceramics are made by heating glass to rearrange its atomic structure into a more regular pattern. As partially crystalline materials, they can tolerate high temperatures, thermal shock
and chemicals. They are useful in many applications, such as heat-resistant cookware, turbine engines, electronic equipment, and missile nose cones. Other glass-ceramics are Pyroceram
and ULE 7971(titanium silicate) developed by Corning Glass, and opaque white Hercuvit, closely related to Cer-Vit, developed for cooktops
by Pittsburgh Plate Glass.
Cer-Vit was flawed by the inclusion of crystals and small bubbles (0.1-0.2mm diameter) resulting from the manufacturing process. In most applications flaws smaller than 0.1mm are not serious, while larger defects are only considered if they lie on or very close to the working surface. The use of Cervit has largely been superseded by that of Zerodur
and Sitall
.
Glass-ceramic
Glass-ceramics are polycrystalline material produced through controlled crystallization of base glass. Glass-ceramic materials share many properties with both glasses and ceramics...
material made up of oxides of silicon, aluminium and lithium, with ultra low coefficient of thermal expansion, used for telesope mirrors and lenses. It was made by Owens-Illinois
Owens-Illinois
Owens-Illinois Inc. is a Fortune 500 company that specializes in container glass products. It is one of the world's leading manufacturers of packaging products, holding the position of largest manufacturer of glass containers in North America, South America, Asia-Pacific and Europe...
Corning
Corning
- Businesses and organizations :* Corning Incorporated* Dow Corning* Owens Corning* Corning Museum of Glass- People :* Edwin Corning , American businessman and politician* Erastus Corning , American businessman and politician...
in 1967, and discontinued in 1978. Cer-Vit and Zerodur are two-phase ceramics consisting of a high percentage of crystalline silica-based material and the remainder of non-crystalline glass. These ceramics also include silica-based glasses such as Homosil fused quartz
Fused quartz
Fused quartz and fused silica are types of glass containing primarily silica in amorphous form. They are manufactured using several different processes...
, soda-lime glass
Soda-lime glass
Soda-lime glass, also called soda-lime-silica glass, is the most prevalent type of glass, used for windowpanes, and glass containers for beverages, food, and some commodity items...
, and the like.
Glass-ceramics are made by heating glass to rearrange its atomic structure into a more regular pattern. As partially crystalline materials, they can tolerate high temperatures, thermal shock
Thermal shock
Thermal shock is the name given to cracking as a result of rapid temperature change. Glass and ceramic objects are particularly vulnerable to this form of failure, due to their low toughness, low thermal conductivity, and high thermal expansion coefficients...
and chemicals. They are useful in many applications, such as heat-resistant cookware, turbine engines, electronic equipment, and missile nose cones. Other glass-ceramics are Pyroceram
Pyroceram
Pyroceram is a material developed and trademarked by Corning Glass during the 1950s. Its development has been traced to Corning's work in developing photosensitive glass. Corning credits S...
and ULE 7971(titanium silicate) developed by Corning Glass, and opaque white Hercuvit, closely related to Cer-Vit, developed for cooktops
Kitchen stove
A kitchen stove, cooking stove, cookstove, or cooker is a kitchen appliance designed for the purpose of cooking food. Kitchen stoves rely on the application of direct heat for the cooking process and may also contain an oven, used for baking.In the industrialized world, as stoves replaced open...
by Pittsburgh Plate Glass.
Cer-Vit was flawed by the inclusion of crystals and small bubbles (0.1-0.2mm diameter) resulting from the manufacturing process. In most applications flaws smaller than 0.1mm are not serious, while larger defects are only considered if they lie on or very close to the working surface. The use of Cervit has largely been superseded by that of Zerodur
Zerodur
Zerodur®, a registered trademark of Schott Glass Technologies, is a lithium aluminosilicate glass-ceramic produced by Schott AG since 1968. It has been used for a number of very large telescope mirrors including Keck I and Keck II. With its very low coefficient of expansion it can be used to...
and Sitall
Sitall
Sitall aka Sitall CO-115M or Astrositall, is a crystalline glass ceramic material with ultra low coefficient of thermal expansion . It was originally manufactured in the former Soviet Union and was used in the making of primary mirrors for the Russian Maksutov telescopes, but since dissolution has...
.