Mechanical properties and microstructure of reaction sintered β′-sialon ceramics prepared by a slip casting method

Reaction sintered β′-sialon ceramics Si_6-zAl_zO_zN_8-z, were prepared by slip casting from α-Si₃N₄, Al₂O₃, and AlN starting powders. The mechanical properties and microstructures of sintered bodies were investigated as a function of composition (varying the z value). The maximum value of the flexural strength, ∼ 600 MPa, and fracture toughness, ∼ 4.1 MPa m^1/2 were observed in the z range of 0.5–1. In the z value range of 2–4, the mechanical properties decreased drastically. This phenomenon is attributed to the variation of fracture energy, which is greatly affected by the sintered crystallite size. This revised version was published online in November 2006 with corrections to the Cover Date.