In: Chemistry
Ceramics are highly brittle materials with very high melting
point. They are basically oxides or mitrides or carbides of metals.
They are more heat and corrosion resistant than metals.
The atoms in ceramic materials are held together by a chemical
bond. The two most common chemical bonds for ceramic materials are
covalent and ionic. For metals, the chemical bond is called the
metallic bond. The bonding of atoms together is much stronger in
covalent and ionic bonding than in metallic. That is why, generally
speaking, metals are ductile and ceramics are brittle.
These are materials held together by either type of bond will tend
to fracture before any plastic deformation takes place. This gives
catastrophic failures, as opposed to the normally much more gentle
failure modes of metals.
For ceramics, the microstructure can be entirely glassy (glasses
only); entirely crystalline; or a combination of crystalline and
glassy.