Synthesis and characterization of beta-Sialon powders from Si, halloysite clay and AlN powders

摘要

Two beta-Sialons, with z-values of 1 and 4, respectively, were successfully synthesized by silicothermal reduction and nitridation method under 0.4 MPa nitrogen pressure. The effect of firing temperatures on the phase transformations and morphologies of beta-Sialons were analyzed by XRD and SEM. For beta-Sialons (z = 1), the product was finally composed of targeted beta-Sialon (z = 1) and secondary phase alpha-Si3N4; for z = 4, beta-Sialon (z = 4) was the main phase, and 15R-Sialon and alpha-Al2O3 co-existed as secondary phases. A higher firing temperature is more beneficial for the phase transformations and crystal growth of beta-Sialons, however, the most suitable firing temperature was 1400 degrees C.