Biomedical Engineering Reference
In-Depth Information
7
Glass-Ceramics
Wolfram Holand
Ivoclar Vivadent AG, Schaan, Principality of Liechtenstein
7.1 GLASS-CERAMICS AND THEIR USES
The name ''glass-ceramic'' already tells us something about this
fascinating material, which was invented in 1959. It is a combination
of the two everyday words - ''glass'' and ''ceramic.'' As we all know
from familiar objects like drinking glasses and windows, glass is usually
transparent. Ceramics are used in scientific and technical fields to make,
among other things, electronic equipment and machines. We also use
them in day-to-day life in the form of cups, mugs, and vases to name
but a few.
In the first chapter of this topic, we introduced you to the material
we know as ''glass.'' We learned that glass is a supercooled, frozen
liquid, which, unlike ceramic, does not contain any crystals, and which
is characterized by what is known as a transition range. We also learned
that glass is made up of different molecular structures and microstruc-
tures (structures visible under a microscope). We were introduced to the
special phenomenon of glass-in-glass phase separation, which occurs in
microstructures. The fact that glasses can separate into different liquids
