ceramics (sərăm`ĭks), materials made of nonmetallic minerals that have been permanently hardened by firing at a high temperature, or objects made of such materials. Most ceramics resist heat and chemicals and are poor conductors of heat and electricity. Traditional ceramics are made of clay and other natural occurring materials, while modern high-tech ceramics use silicon carbide, alumina, and other specially purified or synthetic raw materials. Ceramic materials are used in all forms of pottery pottery, the baked-clay wares of the entire ceramics field. For a description of the nature of the material, see clay .

Types of Pottery

It usually falls into three main classes—porous-bodied pottery, stoneware , and porcelain .
..... Click the link for more information. , from crude earthenware earthenware, form of pottery fired at relatively low temperatures, so that the clay does not vitrify (become glassy), as do stoneware and porcelain clays. Occasionally, earthenware is used as a general term for all kinds of pottery.
..... Click the link for more information. to the finest porcelain porcelain [Ital. porcellana], white, hard, permanent, nonporous pottery having translucence which is resonant when struck. Porcelain was first made by the Chinese to withstand the great heat generated in certain parts of their kilns.
..... Click the link for more information. , and in industrial and engineering products. Ceramic products include cookware and dinnerware; art objects, such as figurines; building materials, such as brick brick, ceramic structural material that, in modern times, is made by pressing clay into blocks and firing them to the requisite hardness in a kiln. Bricks in their most primitive form were not fired but were hardened by being dried in the sun.
..... Click the link for more information. ; abrasives abrasive, material used to grind, smooth, cut, or polish another substance. Natural abrasives include sand , pumice , corundum , and ground quartz . Carborundum ( silicon carbide ) and alumina (aluminum oxide) are important synthetically produced abrasives.
..... Click the link for more information. , such as alumina alumina (əl
..... Click the link for more information. , and specialized cutting tools; electrical equipment, such as insulators in spark plugs; refractories, such as firebrick firebrick, brick that can withstand high temperatures, used to line flues, stacks, furnaces, and fireplaces. In general, such bricks have high melting points that range from about 2,800°F; (1.540°C;) for fireclay to 4,000°F; (2,200°C;) for silicon carbide.
..... Click the link for more information. and the heat shield on the space shuttle space shuttle, reusable U.S. space vehicle. Developed by the National Aeronautics and Space Administration (NASA), it consists of a winged orbiter, two solid-rocket boosters, and an external tank.
..... Click the link for more information. ; and artificial bones and medical devices. The oldest known fired ceramics date from the Paleolithic period some 27,000 years ago.

ceramics

Traditionally, objects created from such naturally occurring raw materials as clay minerals and quartz sand, by shaping the material and then hardening it by firing at high temperatures to make the object stronger, harder, and less permeable to fluids. The principal ceramic products are containers, tableware, bricks, and tiles. See also earthenware, porcelain, pottery, stoneware, terra-cotta.

ceramics

the art and techniques of producing articles of clay, porcelain, etc.
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ceramics [sə′ram·iks]

(engineering)

The art and science of making ceramic products.

Ceramics

Inorganic, nonmetallic materials processed or consolidated at high temperature. This definition includes a wide range of materials known as advanced ceramics and is much broader than the common dictionary definition, which includes only pottery, tile, porcelain, and so forth. The classes of materials generally considered to be ceramics are oxides, nitrides, borides, carbides, silicides, and sulfides. Intermetallic compounds such as aluminides and beryllides are also considered ceramics, as are phosphides, antimonides, and arsenides. See Intermetallic compounds

Ceramic materials can be subdivided into traditional and advanced ceramics. Traditional ceramics include clay-base materials such as brick, tile, sanitary ware, dinnerware, clay pipe, and electrical porcelain. Common-usage glass, cement, abrasives, and refractories are also important classes of traditional ceramics.

Advanced materials technology is often cited as an enabling technology, enabling engineers to design and build advanced systems for applications in fields such as aerospace, automotive, and electronics. Advanced ceramics are tailored to have premium properties through application of advanced materials science and technology to control composition and internal structure. Examples of advanced ceramic materials are silicon nitride, silicon carbide, toughened zirconia, zirconia-toughened alumina, aluminum nitride, lead magnesium niobate, lead lanthanum zirconate titanate, silicon-carbide-whisker-reinforced alumina, carbon-fiber-reinforced glass ceramic, silicon-carbide-fiber-reinforced silicon carbide, and high-temperature superconductors. Advanced ceramics can be viewed as a class of the broader field of advanced materials, which can be divided into ceramics, metals, polymers, composites, and electronic materials. There is considerable overlap among these classes of materials. See Cermet, Composite material, Glass

Typical properties for some ceramic materials
				Partially
	Aluminum	Silicon	Silicon	stabilized
Property	oxide	nitride	carbide	zirconia
Density, g/cm³	3.9	3.2	3.1	5.7
Flexure strength, MPa	350	850	450	790
Modulus of elasticity, GPa	407	310	400	205
Fracture toughness (K_IC),	5	5	4	12
MPa · m^1/2
Thermal conductivity,	34	33	110	3
W/mK
Mean coefficient of thermal	7.7	2.6	4.4	10.2
expansion (× 10^-6/°C)

The general advantages of advanced structural ceramics over metals and polymers are high-temperature strength, wear resistance, and chemical stability, in addition to the enabling functions the ceramics can perform. Typical properties for some engineering ceramics are shown in the table.

Advanced ceramics are used in systems such as automotive engines, aerospace hardware, and electronics. The primary disadvantages of most advanced ceramics are in the areas of reliability, reproducibility, and cost. Major advances in reliability are being made through development of tougher materials such as partially stabilized zirconia and ceramic whiskers; and reinforced ceramics such as silicon-carbide-whisker-reinforced alumina used for cutting tools, and silicon-carbide-fiber-reinforced silicon carbide for high-temperature engine applications.

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Types of Pottery

ceramics

ceramics
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