! Different compositions are used for different applications ! Liquid phase sintering with liquid content controlled by feldspar content ! High feldspar content gives lower firing temperature and high translucency ! High clay content is easier to form into green bodies
Applications
! Dental porcelains need good translucency - high feldspar and low clay ! Low glass content ceramics (high clay) are harder and more resistant to chemical attack! China clays have large particles and give white products - ball clays have very fine particles but
impurities give dark product. Ball clays make easier formed green bodies but give inferior product ! Triaxial porcelains are insensitive to precise composition of clay mix. Thus easy to use in industry