Thermophysical properties of ZrB₂ and ZrB₂-SiC ceramics

Thermophysical properties were investigated for zirconium diboride (ZrB₂) and ZrB₂-30 vol% silicon carbide (SiC) ceramics. Thermal conductivities were calculated from measured thermal diffusivities, heat capacities, and densities. The thermal conductivity of ZrB₂ increased from 56 W (m K)^-1 at room temperature to 67 W (m K) ^-1 at 1675 K, whereas the thermal conductivity of ZrB₂-SiC decreased from 62 to 56 W (m K)^-1 over the same temperature range. Electron and phonon contributions to thermal conductivity were determined using electrical resistivity measurements and were used, along with grain size models, to explain the observed trends. The results are compared with previously reported thermal conductivities for ZrB₂ and ZrB₂-SiC.