Production of Sinterable Si3N4 from SiO2-Li2O-Y2O3 Mixture

Abstract

In this study, fine grained SiO2 was exposed to CRN, and then Si3N4 ceramic powders were produced. Initially, 5wt% Li2O-5 wt% Y2O3 (based on the final product) and carbon black were added to SiO2, and then powder samples were processed to carbothermal reduction for 3 hours at 1,450 degrees C and 1,475 degrees C under nitrogen gas flow (1 lt/m). In order to burn the access carbon, the powder samples were held at 900 degrees C for 1 hour in furnace atmosphere. Having completed to Li2O and Y2O3 added Si3N4 powders, these were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectroscopy (EDS) methods. In addition, the values of wt% alpha-Si3N4 were estimated from XRD peak heights. The optimum temperature and holding time were determined for the best Si3N4 transformation process.