Glass and Ceramics hold
the promise to change our lives in the way that Plastics have done.
A great deal of money has been put into research with some results,
but still short of the dream.
Ceramics are composed of inorganic nonmetallic materials such as
oxides, nitrides, borides, and carbides. Ceramics can be broken
down into two groups, the "traditional" ceramics (which
includes glass, pottery, brick, and refractories) and "advanced"
ceramics, which are the newer materials developed since the 1960's.
Glass is generally considers to be a subset of ceramics, however
since its use is so wide spread it warrants sharing the heading.
Glass is used in a wide variety of applications, from the obvious
sheet glass used in windows, and containers, to more specialized
glasses used for dishware (home and laboratory).
Even in the solid form, its structure is more like a "liquid"
than a solid. It is actually a super cooled liquid somewhat similar
to "Taffy". ASTM defines the material as an inorganic
product of fusion that has been cooled to a rigid condition without
crystallizing. It is an amorphous material (As glass is cooled it
become less plastic in its behavior and more brittle. It, like taffy
is also "rate" sensitive. If you bend a piece of glass
that has been heated to a temperature where it still maintains its
form, it can be bent and shaped. but if you bend it too quickly,
it may break.
Most glasses are made up of Silicates. Soda Lime Glass accounts
for approximately 90% of all glass tonnage produced. The glass is
relatively easy to melt from basic raw materials and is used for
containers, flat glass, and lighting products. Borosilicate glasses
have lower coefficients of expansion and good resistance to chemical
attack. They are used on ovenware and sealed beam headlights. A
third group a glasses are the aluminosilicate glasses, these glasses
contain alumina in an alkali silicate glass. These aluminosilicate
glasses have higher temperature properties and can be used in stove
Glass-Ceramics contain both
Ceramic Materials (other than "glass") are most often
formed by producing parts from powder, and sintering them. The proper
mix of powder elements is mixed with a binder and then fired at