Responding to Temperature Changes

Abstract

Heat is essentially the vibration of atoms in a material. Consequently thermal properties reflect the type and strength ofinteratomic bonding and the crystal structure. The important thermal properties of any material are– Heat capacity– Coefficient of thermal expansion– Thermal conductivityThermal properties of ceramics differ from those of metals whenever free (conduction) electrons are involved, such as in thermalconductivity. However, heat transfer by phonon (lattice vibration) transport can in some cases be more effective than throughthe movement of electrons. We describe melting and vaporization of ceramics as the temperatures for these transformationstend to be high, which can be critical in certain applications, such as the tiles on the space shuttle, but present problemsduring processing. It should also be obvious by now that heat affects many of the properties of ceramics such as Young’s modulus,electrical conductivity, magnetic behavior, and dielectric constant. There are major applications that utilize the variedthermal properties of ceramics, from high thermal conductivity substrates for electronic packaging to enormous mirror blanksfor telescopes that have “zero” expansion.