Effect of Cooling Cycle after Sintering on the Thermal Diffusivity of Y<sub>2</sub>O<sub>3</sub> Doped Si<sub>3</sub>N<sub>4</sub> Ceramics

Abstract

As a result of the studies that have been made for increasing the thermal conductivity of Si3N4, increasing thermal conductivity values have paved the way for the technologic applications such as using the Si3N4 in electronic devices as heatsink and substrate. Two important parameters such as density and grain boundary phase that affect the thermal conductivity of the Si3N4 ceramics are based on the sintering additives and techniques. Exposure time to gas applied in the sintering and cooling cycle after sintering are the critical factors that affect the intergranular phase crystallization. In this study, the effect of Y2O3 doped Si3N4 ceramics and different cooling cycle after gas-pressure sintering to the phase crystallization and thermal diffusivity was researched. The samples were subjected to two different cooling cycles after sintering. The thermal diffusivity value of the sample applied by slow cooling cycle is 17.79 mm2/sec, the sample applied by rapid cooling cycle is 16.2 mm2/sec. As a result of slow cooling cycle, the crystallization has increased but thermal diffusivity has decreased at the rate of ~ 8.94%.