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.