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, 5 wt% 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°C and 1,475°C under nitrogen gas flow (1 lt/m). In order to burn the access carbon, the powder samples were held at 900°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% α-Si₃N₄ were estimated from XRD peak heights. The optimum temperature and holding time were determined for the best Si₃N₄ transformation process.

Keywords:

• Powder synthesis
• Silicon nitride
• Sintering additives