Improved Thermal Diffusivity Method Applied to TiB2, ZrB2, and HfB2 from 200°–1300°C

The thermal diffusivities of dense polycrystalline TiB₂, ZrB₂, and HfB₂ were measured by a laser flash method over the temperature range 200°–1300°C. An investigation of the effects of radial heat flow was performed and a special sample shape was used to comply with the assumption of one‐dimensional heat flow. The values of the diffusivities were found to be described by the empirical equations $$\begin{array}{c}{\alpha }_{{\mathrm{TiB}}_2}{\text{=0.1290+[39.26/T(}}^{\circ }\mathrm{K}\mathrm{)]}{\mathrm{cm}}^2/\sec \\ {\alpha }_{{\mathrm{ZrB}}_2}{\text{=0.1424+[81.17/T(}}^{\circ }\mathrm{K}\mathrm{)]}\\ {\alpha }_{H{\mathrm{fB}}_2}{\text{=0.1436+[35.97/T(}}^{\circ }\mathrm{K}\mathrm{)].}\end{array}$$ Values of thermal conductivity computed from the diffusivity data were found to be described by $$\begin{array}{c}{\lambda }_{{\mathrm{TiB}}_2}{\text{=0.7867+[10.30/T(}}^{\circ }\mathrm{K}\mathrm{)]}\mathrm{W/cm}\hspace{0.17em}\mathrm{deg}\\ {\lambda }_{{\mathrm{ZrB}}_2}{\text{=0.8235+[108.2/T(}}^{\circ }\mathrm{K}\mathrm{)]}\\ {\lambda }_{H{\mathrm{fB}}_2}{\text{=0.7157+[34.24/T(}}^{\circ }\mathrm{K}\mathrm{)].}\end{array}$$