SiAION MATERIAL AND CUTTING TOOLS MADE THEREOF

摘要

This invention discloses a SiAION-based ceramic particularly suited for use as a cutting tool in the high speed chip forming machining of metals. The ceramic is composed of a SiAION matrix including a) a phase of alpha' SiAION represented by the general formula of Mx(Si,AL)12(O,N)16, wherein 0 and a hardness of greater than 93.5 Rockwell on the A scale. Optionally, the ceramic may also contain a dispersed phase of substantially inert materials selected from the known oxides, carbides, oxy-carbides, silicides, nitrides, carbo-nitrides and alloys or mixtures thereof of one or more of the element Ti, Zr, Hg, Nb, Ta, V, Cr, Mo, W, B and Si. The ceramic may be formed into a cutting tool insert for metal machining. Methods of preparing the ceramic material, most preferably by microwave sintering, are also provided. the use of microwave sintering is found to improve both the hardness and toughness properties, while avoiding the need for pressure sintering. The ceramic, or the cutting tool insert formed from the ceramic, may be provided with a partial or complete coating of a hard refractory material.