Combustion synthesis of single-phase β-sialons (z=2-4)

Single-phase beta-sialon powders (z = 2-4) have been prepared with homogeneous compositions by the combustion synthesis. The raw materials (Si, Al and SiO2) were combusted under N-2 pressure of 1 MPa. Without using a diluent, the reaction temperatures were very high (>2000 degrees C) and the combustion products contained Si and Al residues. With addition of commercial beta-sialon (z = 1) as a diluent (up to 50 wt%), both the reaction temperatures and amount of residual Si and Al significantly decreased. The combustion reactions completed at 50 wt% dilution, and pure beta-sialon phases were synthesized. When the combustion product itself is used instead of the commercial diluent, the phase content of desired z value increased with the repetition times until a single-phase powder is produced. The sinterability of the synthesized powders was then tested using 5 wt% Y2O3 as a sintering aid by the spark plasma sintering (SPS). (C) 2010 Elsevier Ltd. All rights reserved.