Page 4 - Curriculum Visions Dynamic Book

(Above) All minerals – not just silicates (clay) – are ceramics as far as materials science is concerned. These beautiful stones are just as much ceramics as a brick in a wall.
See Vol. 5: Glass for more on glass.
(Below) Ceramics tend to be brittle and so can easily be broken with a sharp blow.
1: Introduction
The word “ceramic” comes from the Greek keramikos, meaning potter’s clay. In general use the word “ceramic” means anything made of clay that has been hardened by heat. In materials science the word has gradually become to be used more widely and means any material or product, including pottery or brick, that is made from a mineral, and that is crystalline and usually brittle. This definition, which is used in this book, includes minerals such as diamond that have a crystalline structure. It does not include glass, which has a special structure of its own.
In practical terms ceramics are usually hard, strong, brittle solids that will stand up to heavy wear and high temperatures.
Many ceramics do not conduct heat or electricity very well. They do, however, resist reacting with acids, alkalis, and liquids that might dissolve other materials.
Ceramics do not “weather” – that is, unlike metals that tarnish or rust, they do not change when exposed to rain, sunlight, cold, and so on.
Ceramics can also be easily decorated.
Because the definition of ceramics covers a surprisingly large range of materials, from bricks, cups, and saucers to diamond, graphite, and silicon chips, ceramics also have a wide variety of properties. Diamond, for example, conducts heat better than copper, and graphite and zirconium dioxide (zirconia)
are excellent conductors of electricity.
Some ceramics, especially when other things
are added to them, can also occur in forms that make them less brittle than we might
expect.
But whatever the properties of any
particular ceramic, its properties are always the result of its chemistry, both in
the elements that go into it and the way they are bonded together.
4