What are Ceramics ?


 Ceramics are generally compounds between metallic and nonmetallic elements and include such compounds as oxides, nitrides, and carbides. Typically they are insulating and resistant to high temperatures and harsh environments.   They are inorganic, nonmetallic materials  that can be crystalline or amorphous (glassy). Though used since ancient times (the first ceramics were made by firing earthy materials,  especially clay, at least as early as  24,000 B.C.), ceramics in forms both familiar and  new remain essential materials. Modern ceramics include structural clay  products such as bricks, sewer pipes, and tiles; white-wares, refractories; glasses (including  fibers for communication – optical fibers); abrasives;  and cements. And then there are so-called advanced ceramics. Among these are structural materials used for engine components and other parts subject  to a lot of wear; for cutting tools;  and for bio-ceramics such as bone and tooth replacements. Advanced ceramics are  also used in capacitors,  resistors, insulators, piezo-electrics, magnets, superconductors, and electrolytes. Coatings are used to protect engine components and other parts from  fast wear and/or corrosion. Still other advanced ceramics are used for making filters, membranes, catalysts,  and–crucial  for the automobile industry–catalyst  supports. 

Many materials scientists are engaged in developing new ceramic materials and improving existing ones. This involves understanding the properties of  the materials so as to tailor them  for new applications.  For example,  doping–adding chemical elements that are not present in the starting material–can change the electrical conductivity of a ceramic by many orders of magnitude,  or change the type of conduction from  electronic to ionic. Such conductivity changes are critical for electrochemical sensors and for  materials used in  clean energy production in solid-oxide fuel cells. Materials scientists also  play a vital role  in  devising processes for joining ceramics with other materials, including metals and  semiconductors,  to make new products.  Knowledge of properties is needed to overcome difficulties such  as mismatches in thermal expansion that can  become critical when temperature changes during the  manufacture or use of a device. Products made entirely or partly from  ceramics are everywhere around us today and promise to be prominent in the technologies of the future. 

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