Thermal Conductivity: XIV, Conductivity of Multicomponent Systems

Abstract

The thermal conductivity of a number of multi‐component systems has been determined as a function of composition and temperature. These were silicate glasses, MgO‐NiO, Al 2 O 3 ‐Cr 2 O 3 , UO 2 ‐UO 2+x ‐ThO 2, ZrO 2 ‐HfO 2 ‐CaO, MgO‐Mg 2 ‐SiO 4 , MgO‐BeO, Al 2 O 3 ‐mullite, MgO‐MgAl 2 O 4 , Al 2 O 3 ‐ZrO 2 , Al 2 O 3 ‐glass, and Si‐Sic. Analyses of these results indicate that a second component in solid solution markedly lowers the thermal conductivity. The second‐component scattering mean free path is inversely proportional to concentration at low concentrations and independent of temperature at the temperatures studied (above room temperature). The conductivity of polyphase ceramics can be predicted if the conductivity of each phase, amount of each phase, and phase distribution (including pore phase) are known.