ADVANCED CERAMICS
Once we hear the word ceramic, immediately ceramics products such as pots, pans, teacups, bricks, tiles etc. come to our mind. All such clay products come under traditional ceramics. To understand the difference between traditional ceramics and modern day advanced ceramics some explanations are required. Chinaware and sanitary ware come under traditional ceramics. Refractory’s, such as alumina (AL2O3), silica (SIO2), used extensively in both ferrous and non ferrous industries for lining furnaces are also traditional ceramics. One typical characteristic of these traditional ceramics is that all of them use material/minerals occurring in their natural state. In contrast to these traditional ceramics, advanced ceramics are manufactured from highly refined specially prepared raw materials using chemical processing techniques. The starting materials for advanced ceramic manufacture are therefore mot naturally occurring minerals, but rather materials that have already undergone chemical transformation and refinement, prior to use in a ceramic part.
Advanced ceramics find diverse applications in modern industry. They are used as abrasives for grinding and polishing, in cutting tools, in several parts of automobiles and other car engines, in spark plugs, as electronics/electrical insulators and on the heat shields of rockets and satellites. Superconducting ceramics and ceramic biomaterials promise to transform the entire industrial scene.
Modern advanced ceramics may be defined as primarily inorganic and non-metallic materials formed as a powder, which are compacted into various shapes and consolidated or densified through firing at high temperatures. Here we are dealing with more complex inorganic compounds like titanates, noiobates etc. as well as with non-metals such as oxides, carbides, borides, nitrides etc.(though glasses are primarily made from inorganic materials, they are to be dealt separately). The starting material for advanced ceramics manufacture is powder. The purity, the sphericity of the powder particles, their size and distribution are important elements determining the properties of the products. To form ceramics composites, ceramics are to be combined with other materials like plastics, metals and alloys. For these applications the ceramics is normally in the form of a continuous long fibre, short fibre or in the form of small whiskers. Thus production of ceramics requires not only the production of high quality powders, but also the production of the starting powder/fibres that have to be compacted to the required shape and then heated to high temperature to achieve the final consolidated product having the required shape.
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