Glass-ceramics technical applications

Period of Wide Technical Application. In the time between 1930 and 1940 work was done on various applications for the rare earth elements. Particularly successful was the production of sunglasses ("Neophan"), polishing media from rare earth oxides to replace iron oxide, decolorization of glass using cerium oxide, pure cerivim oxide as opacifier in ceramic glazes, use of cerium... 

The discovery of glass-ceramics as a new type of solid with unusual parameters and their rapid laboratory development have outrun the possible applications. At present, glass-ceramics have found chief application in technical fields where their specific mechanical, thermal, electrical and other properties are exploited, and in the building industry which has been focusing its attention at elements made from cheap natural or waste materials. 

Oxides are widely used and encountered in technical applications, such as high-temperature ceramics, nuclear fuels, glasses, and corrosion layers on superalloys. 

Silica, the main component of silicates, is widely used as mentioned earlier. In its crystalline and noncrystalline polymorphs, silica is used industrially as a raw material for glasses, ceramics, foundry molds, in the production of silicon, and more recently in technical applications such as quartz oscillators and optical waveguides for longdistance telecommunications. Of the crystalline forms, only a-quartz is commonly used as sand or as natural and synthetic single crystals. Cristobalite is often utilized as the synthetic phase in glass-ceramics. 

Ceramics for use in technical applications are often divided into the groups traditional , engineering , electroceramics and glass . Define each of these categories and give a typical use for a material from each group. [Note answer is not provided at the end of this book.]... 

The compositions of P-quartz solid solution glass-ceramics produced on a large scale for technical applications are summarized in Table 2-7. These glass-ceramics are called Vision , Zerodur , Narumi , Neoceram , Ceran , and Keraglas . Other products are Robax , which represents a col-... 

Vitron SpezialwerkstofFe GmbH, Jena, Germany, manufactures a machinable glass-ceramic called Vitronit . It is used for technical applications. 

Selected examples in Section 4.4.2.6.B are used to describe the processes that are suitable to achieve optimal joining of the different materials. In addition, measuring methods for evaluating the results were carried out. These glass-ceramic-metal composites for dental applications demonstrate that a multicomponent glass-ceramic and metals can be used for a variety of applications in medical and technical fields. 

The success of Ceran is partly also due to the experience and knowhow gained in the development and production of Zerodur . Schott already started producing this technical glass ceramic in the 1960s. With its exceptional temperature stability (non-deforming when subjected to variations between —20°C and - -100°C) Zerodur has become the material of choice for optical precision applications such as space telescopes, for example (see Chap. 4). 

To make each volume sufficiently intelligible, the necessary fundamentals from chemistry, physics, and engineering are described or referred to via citations. We see this as the best way to enable all our potential business partners who are not already familiar with glass and glass ceramics to compare these materials with alternatives on a thoroughly scientific basis. We hope that this will lead to intensive technical discussions and collaborations on new fields of applications of our materials and products, to our mutual advantage. 

Photonic Applications. Several areas of application of glass-ceramic materials are emerging in the photonic and optical communications fields. These include lasers and frequency up-conversion devices in which the optical advantages of fluorescent rare-earth ions in crystalline host materials are combined with manufacturing and structural advantages of glass. Their technical importance and commercial impact is not yet clear. 

Part 3 Classes of Materials starts with the selective treatment of metals that are applied as base and alloying elements of metallic materials. The next class of materials discussed are ceramics. Detailed groupings and definitions of technical ceramics are given and traditional ceramics and cements, silicate ceramics, refractory ceramics, oxide ceramics, and nonoxide ceramics are treated. The physical and physicochemical properties of those polymers, copolymers, and polymer blends which are widely used for scientific applications and in industry are described in the next chapter. The last chapter serves as a source of data and commercial product information on glasses as engineering materials of practical importance. 

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