Ceramics, refractories

Sectioning Diamond wheel Mounting Hot mounting in epoxy  

Step Abrasive Grain size (pm) Working surface Lubricant and coolant Load RPM Time min 

Grinding Diamond 30 Disk or film Water 20 200 Until flat 

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Aluminosilicate Fibers. Vitreous alurninosihcate fibers, more commonly known as refractory ceramic fibers (RCF), belong to a class of materials known as synthetic vitreous fibers. Fiber glass and mineral wool are also classified as synthetic vitreous fibers, and together represent 98% of this product group. RCFs were discovered in 1942 (18) but were not used commercially until 1953. Typical chemical and physical properties of these materials are shown in Table 3. 

Table 3. Typical Physical and Chemical Properties of Refractory Ceramic Fibers...

Sihca and aluminosihcate fibers that have been exposed to temperatures above 1100°C undergo partial conversion to mullite and cristobaUte (1). Cristobahte is a form of crystalline siUca that can cause siUcosis, a form of pneumoconiosis. lARC has deterrnined that cristobaUte should be classified as 2A, a probable carcinogen. The amount of cristobahte formed, the size of the crystals, and the nature of the vitreous matrix in which they are embedded are time- and temperature-dependent. Under normal use conditions, refractory ceramic fibers are exposed to a temperature gradient, thus only the hottest surfaces of the material may contain appreciable cristobahte. Manufacturers Material Safety Data Sheets (MSDS) should be consulted prior to handling RCF materials. 

Diamond and Refractory Ceramic Semiconductors. Ceramic thin films of diamond, sihcon carbide, and other refractory semiconductors (qv), eg, cubic BN and BP and GaN and GaAlN, are of interest because of the special combination of thermal, mechanical, and electronic properties (see Refractories). The majority of the research effort has focused on SiC and diamond, because these materials have much greater figures of merit for transistor power and frequency performance than Si, GaAs, and InP (13). Compared to typical semiconductors such as Si and GaAs, these materials also offer the possibiUty of device operation at considerably higher temperatures. For example, operation of a siUcon carbide MOSFET at temperatures above 900 K has been demonstrated. These devices have not yet been commercialized, however. 

A type of clay composed of mixed silicates and used for refractories, ceramics, tile and stoneware. 

Proceedings of the International Symposium on the Decomposition of Organo-metallics to Refractory Ceramics, Metals, and Metal Alloys, ed. K. S. Masdiyasni, University of Dayton Press, Dayton, Ohio, 1968. 

Baney, R. H. Division of Industrial and Engineering Chemistry, I. Structural, Electronic and Refractory Ceramics, ACS Symposium on Materials in Emerging Technologies, 1985. 

J. R. Hague, J. F. Lynch, A. Rudnick, F. C. Holden, and W. H. Duckworth, eds., Refractory Ceramics for Aerospace A Materials Selection Handbook, The American Ceramic Society, Inc., Columbus, Ohio, 1964. 

Stone, R. Refractory Ceramic Fibers. Science. 1356 (March 13. 1992). Tweedale, (J, P. Hansen, and l-. Newall Magic Mineral to Killer Dust, Oxford University Press, Inc., New York, NY. 2000. 

Aipe, Hans-.Tingeii, W Rnssey, Ci Schulz, and S Hawkins Ullmann s Encyclopedia of Industrial Chemistryt Refractory Ceramics to Silicon Carbide, John Wiley Sons, Inc, New Yoik. NY, 1997. 

Aluminum oxide is used in the production of aluminum manufacture of abrasives, refractories, ceramics, electrical insulators, catalyst and catalyst supports, paper, spark plugs, crucibles and laboratory works,... 

Hasselman, D.P.H. (1970), Thermal stress resistance parameters for brittle refractory ceramics a compendium , Am. Ceram. Soc. Bull, 49, 1033-1037. 

Magnesia-spinel (MgAI204) refractory ceramic composites 361... 

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