Abstract: It is provided a sintered body on the basis of ?-sialon and 15R-sialon, which as a cutting material has a high cutting performance as compared to workpieces made of nickel-based alloy or Heat Resistant Super Alloys. For this purpose, a ceramic sintered body is shown, which includes a sialon phase and an amorphous or semi-crystalline grain boundary phase. The sialon phase includes a proportion of 20-80 wt-% of 15R-sialon polytypoid. The amorphous or semi-crystalline grain boundary phase possibly includes an Yb—Al garnet and constitutes up to 15 wt-% of the entire sintered body. The sintered body is manufactured from an inorganic raw material mixture which includes 40 to 57 wt-% of Si3N4; 40 to 55 wt-% of a mixture of AlN and Al2O3, wherein the ratio of Al2O3 to AlN lies in the range of 1-1.5:1, and 3 to 5 wt-% of Yb2O3 as sintering aid.

Abstract: A sintered molded article includes a ceramic of ?/?-sialon having a grain boundary phase, the grain boundary phase containing at least one hard material formed in situ as an additional phase. A method for the production of the sintered molded article uses at least the following compounds as a starting material: Si3N4, AlN, and, if applicable, Al2O3, at least one oxide of the rare earths, and at least one oxide of the element titanium.

Abstract: The invention relates to ?/?-sialon-based materials. The invention particularly relates to ?/?-sialon-based materials that have an improved sintering activity and impart high edge strength to the sintered molded articles made of said materials.