Effect of a Small Amount of SiO<sub>2</sub> on the Reaction during Sintering in the Si<sub>3</sub>N<sub>4</sub>-Y<sub>2</sub>O<sub>3</sub>-AlN System

A sialon composite consisting of Y-α′-sialon and β′-sialon is obtained by hot-pressing mixtures of Si3N4, Y2O3 and AlN powders. In this study, the effect of the presence of a small amount of SiO2 on the reaction during sintering, especially on the formation of Y-α′-sialon, is investigated. The sinterability of mixtures of Si3N4, Y2O3 and AlN powders was remarkably improved by the addition of a small amount of SiO2. The amount of Y-α′-sialon after sintering decreases with increasing amounts of SiO2 added to the starting mixtures, while the lattice constants, hence the solubility of Y-α′-sialon and β′-sialon, remain unchanged.