Thermal conductivity of submicrometre particles: carbon blacks and solid solutions containing C, B and N

Small particles of carbon blacks, of boron nitrides, of binary (CxBy) and o f ternary (CxByNz) solid solutions have been prepared and then investigated as good thermal insulators at high temperature. Using a flash method with a short uniform and intense thermal pulse, the thermal diffusivity of the s amples has been determined at room temperature. Following an analytical tec hnique, the different contributions of the thermal conductivity (conduction in solid and gas phases, convective and radiative transfers) have been inv estigated. After analysing the different parameters as functions of the gas pressure and the particle size, we are able to express the intrinsic therm al conductivity of these submicrometre powders.