Role of liquid sintering aids in the synthesis of SiAlON materials

Abstract

The synthesis of dense sintered sialon with external additives selected from the system Y2O3-AlN-SiO2 is described. The highest density (3.21g/cc) was achieved at 1750ºC at 90 min of sintering with 5 wt% additive. Non-oxide ceramic materials are increasingly coming out as a potential candidate in engineering applications and among them, sialon is one of the most important materials. β-Sialon was first to be discovered in this class of compounds. It has an excellent combination of thermal, mechanical and chemical properties. The degree of sialon substitution increased with the amount of liquids, the YSiO2N crystalline phase formed concurrently. Strength degradation occurred above 1000ºC.The fracture toughness of the material sintered with a lower amount of sintering aid remained relatively unchanged to 1200ºC.