Heat-conductivity studies of structural ceramic materials. Part VII. Heat conductivity of an Si3N4-based ceramic

The heat conductivity of an Si^sub 3^N^sub 4^-based ceramic is studied. A sintered silicon carbide, prepared from ultrafine (0.5 μm) powder Si^sub 3^N^sub 4^ with aluminum and yttrium oxides added to form a liquid phase and thus to activate the sintering process, is used for the study. The Si^sub 3^N^sub 4^-based ceramic has a heat conductivity higher than that of an oxide-based ceramic. The approximation function for heat conductivity at temperatures below 1400 K has a negative slope, that is, the effective heat conductivity tends to decrease with temperature. Above 1400 K, the effective heat conductivity tends to increase.[PUBLICATION ABSTRACT]