Thermal conductivity behavior of boron carbides

Abstract

Knowledge of the thermal conductivity of boron carbide is necessary to evaluate its potential for high-temperature thermoelectric energy conversion applications. We have measured the thermal diffusivity of hot-pressed boron carbide ${\mathrm{B}}_{\mathrm{x}}$C samples as a function of composition (4\ensuremath{\le}x\ensuremath{\le}9), temperature (300--1700 K), and temperature cycling. These data, in concert with density and specific-heat data, yield the thermal conductivities of these materials. We discuss the results in terms of a structural model that has been previously advanced by two of us (D.E. and C.W.) to explain the electronic transport data. Some novel mechanisms for thermal conduction are briefly discussed.