The word ceramic comes from an ancient Greek word for
“burned earth”. Ceramics are made by firing (heating) clay (fine
particles of earth) in an oven called a kiln or furnace. China, bricks, and
tiles are made from ceramics. Over the past few decades, ADVANCED CERAMICS have been developed with superior or additional properties to
traditional ceramics.
Porcelain has the finest texture of all ceramics. It is made from a
white clay called kaolin, fired at very high temperatures. Most ceramics let
water through until they are glazed, but porcelain is naturally water-resistant
already. It is valued for its glassy smoothness and translucency.
Ceramics can be thrown (made) by shaping a lump of wet clay on a
wheel (a turning plate). The potter places the clay on the centre of the wheel,
then skilfully raises it into shape by hand.
The pot is fired in a kiln. The first firing, called the bisque
firing, hardens the clay. A coating called a glaze is painted onto the pot, and
the pot is fired again. Glaze waterproofs the pot.
Once glazed, a decal (relief) is pre-soaked and smoothed onto the
pot. The pot is fired again to stick the decal to the pot permanently. Pots can
also be painted with enamel and then fired.
BIOGRAPHY: JOSIAH WEDGWOOD English, 1730-1795
This master potter and industrialist introduced many kinds of
coloured pottery. He is best known for his Jasper Ware, with classical designs
in white on blue or green. He also invented a pyrometer to measure kiln
temperature.
Bio-ceramics now replace teeth and bones. They are one
example of advanced ceramics. Each type is made from a particular component of
pure clay. It is heated at a specific temperature, sometimes in a specific gas
environment, such as nitrogen. This changes the ceramic’s chemical
structure and properties.
One type of advanced ceramic, called shuttle ceramic tiles, has
been created to withstand temperatures up to 1,280°C (2,336°F).
Space shuttles are covered in 30,000 of these lightweight tiles. They protect
the shuttle from heat when it re-enters Earth’s atmosphere from
space.
