Thermal conductivity of pressureless sintered silicon nitride materials with LiYO2 additive

Si3N4 ceramics with different microstructures were prepared by pressureless sintering, using LiYO2 as a sintering additive. The effect of micro structural parameters, such as grain size and volume of intergranular phase on thermal conductivity was studied. Materials with thermal conductivities of 26-38 W?(m?K)-1 were obtained by changing the amount of sintering additive. The highest conductivity was measured for the material with the least amount of additive. Since the phase composition is the same for all sintered materials the difference in thermal conductivity is attributed to the amount of glassy phase in the grain-junctions. .