Abstract
In this work, the processing of sintered reaction-bonded silicon nitride (SRBSN) has been applied to the development of high thermal conductivity Si3N4 materials because of its moderate cost of production. Two systems of Yb2O3-MgO (YM system) and Yb2O3-MgO (YbM system) were chosen as the sintering additives. The post-densification behaviour and thermal conductivity of SRBSN were strongly dependent on the type and amount of sintering additives. YbM system exhibited superiority over YM system in enhancing the thermal diffusivity, but it showed poor sinterability. In both additive systems, the increase of the additive amount contributed greatly to the post-densification, but resulted in the decrease of thermal conductivity of SRBSN. Thermal conductivity over 110 W/(m×K) has been reached for SRBSN materials with YM by optimising the additive amount and post-sintering conditions.
