Hot pressing of α-sialon powder prepared by SHS method

Abstract

α-Sialon powder was made from α-Si3N4, Si, Y2O3 and AIN powders by a SHS process under 3 MPa nitrogen pressure. Hot pressing of the α-Sialon powder with added 0–8 wt.% YAG (Y3Al5O12) at 2223 K for 1.5 hr under 30 MPa resulted in α/β-Sialon composites. α-Sialon content of the hot pressed sample was decreased as YAG content was increased. The number of elongated α- and β-Sialon grains was increased as the YAG content was increased. Vickers hardness of the hot pressed α/β-Sialon composites was decreased as the YAG content was increased, while both the fracture toughness and the flexural strength reached their maxima at 2 wt.% YAG addition.