The Effect of Grain Boundary Phase Amount Change on Thermal Conductivity in Rare Earth Oxide (Y2O3) Dopped Si3N4 Advanced Technology Ceramics

Abstract

In this study, in the fixed phase ratio, the grain boundary phase amount was reduced by 10%, the grain boundary phase amount was determined in the Y₂O₃/SiO₂/MgO-Si₃N₄ ceramic system, which was sintered at 1775 ° C for 4 hours at 5 bar pressure and prepared by using lower cost starting Si₃N₄ powder (Silzot). The effect of and distribution on thermal conductivity has been studied. Phase analysis with XRD and image analysis with SEM were performed. Thermal diffusivities were measured with the Laser Flash Method. Y₂Si₃O₃N₄ secondary crystalline phase was observed in XRD patterns. With the reduction of the grain boundary phase, the amount of liquid phase decreased from 11.83% to 10.6%, ~ 10.40%. Thermal diffusivity has decreased from 17.29 mm²/s to 15.97 mm²/s by ~ 7.64. Thermal conductivity decreased ~ 7.37% from 39.10 W/m.K to 36.23 W/m.K.