Thermal conductivity of hot-pressed hexagonal boron nitride

Abstract

The thermal conductivity parallel and perpendicular to the hot-pressing direction of hot-pressed h-BN was measured to investigate the effects of oxide additive species and compositions on the thermal conductivity. CaO, MgO, Y2O3, Yb2O3, and their mixtures were selected as oxide additives owing to their previously demonstrated ability to enhance the thermal conductivities of non-oxide materials such as AlN and Si3N4. The investigated additive concentrations were calculated to be 5, 10, and 15vol%. A thermal conductivity of approximately 210W/m·K was attained by hot-pressing mixed powders of h-BN and a Yb2O3–MgO or Yb2O3–CaO additive at a concentration of 15vol%.