What Are Ceramics
Ceramics once referred purely to pottery and to articles made by firing materials extracted from Earth. Today, the term has a much broader definition. Ceramics are generally thought of as inorganic and nonmetallic solids with a range of useful properties, including very high hardness and strength, extremely high melting points, and good electrical and thermal insulation.
The best-known ceramics are pottery, glass, brick, porcelain, and cement. But the general definition of a ceramic—a nonmetallic and inorganic solid—is so broad that it covers a much wider range of materials. At one end of the scale, ceramics include simple materials such as graphite and diamond, made up from different crystalline arrangements of the element carbon. But at the other end of the scale, complex crystals of yttrium, barium, copper, and oxygen make up the advanced ceramics used in so-called high-temperature superconductors (materials with almost no electrical resistance). Most ceramics fall somewhere between these extremes. Many are metal oxides, crystalline compounds of a metal element and oxygen. Others are silicides, borides, carbides, and nitrides, respectively made from silicon, boron, carbon, and nitrogen. Some of the most advanced ceramic materials are combinations of ceramics and other materials known as ceramic matrix composites (CMCs).