Abstract: Sialon materials contain HFO2 in a maximum of 1 mass-% as a sintering additive, methods of producing them and methods of using them an ?/?-SiAlON material with 5 mass % to 50 mass %, ?/(?/?) RE-?-SiAlON wherein RE stands for at least one cation selected from the group consisting of Y, Sc, Lu, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Mg or Ca, and 95 mass % to 50 mass %, ?/(?/?) ?-SiAlON and of an Hf-containing amorphous or partially crystalline grain-boundary phase with a proportion with respect to the overall material is below 10 vol %, wherein the Hf content of the sintered material is 0.2 mass % to 1.0 mass %, and of a dispersion phase comprising globular particles with a mean particle size of from 0.

Abstract: Know Si3N4 and SiAlON cutting materials become, at the beginning, rounded very quickly on the cutting edge during usual long continuous cuts in gray cast iron (GG) which is described as initial wear. The invention thus provides that the raw material mixture of the material comprised of: component A, an alpha/beta SiAlON, and; component B, a hard material, has a composition consisting of 70 to 97% by volume of component A and 3 to 30% by volume of component B.