Thermal Conductivity of Al_2O_3-ZrO_2 Composite Ceramics

摘要

The Al_2O_3-ZrO_2 composite ceramics were prepared by slip casting in plaster molds and sintering at 1350℃ in air. The composition of prepared samples varied from pure alumina to doped zirconia (3Y-TZP) with steps of 10 vol%. The relative density of the sintered samples varied from 94% to 98%, depending on the composition. Thermal diffusivity of sintered samples was measured by means of the xenon flash method at 100℃, 200℃, 400℃, 600℃, 800℃, and 1000℃ and thermal conductivities were calculated based on measured bulk densities and specific heat data and finally corrected for porosity effects. As expected, the thermal conductivity decreased with increasing zirconia content, and in the case of samples with higher alumina content, it also decreased with increasing temperature. Effective thermal conductivities are close to the lower Hashin-Shtrikman bound and the recently proposed sigmoidal average. Empirical relations were used to fit the dependence of effective thermal conductivity of Al_2O_3-ZrO_2 composite ceramics on both composition and temperature.