SiAlON Composite Ceramics

Abstract

Multi-phase SiAION ceramics offer great scope for property design by controlling the types of phases present and the microstructure development. The most common SiAION composites are the pressureless sintered, glassy-phase containing β or α-β SiAION ceramics, where the presence of α SiAION acts as a means of controlling the hardness and the growth of elongated β SiAION crystals in the microstructure improves the toughness. The SiAION ceramics can also be reinforced by separate additions of other hard, refractory compounds such as SiC and TiN. The best effect is obtained if different toughening mechanisms are combined. The phase composition and microstructure of SiAION composites are discussed and related to some observed mechanical properties.