SILICON NITRIDE CERAMIC AND CUTTING TOOL MADE THEREOF

摘要

Provided is a silicon nitride based ceramic which is particularly useful for use as a cutting tool (10) in the high speed chip forming machining of metallic materials. The ceramic is preferably composed of at least 85 volume percent (v/o) beta silicon nitride phase and less than about 5 v/o intergranular phase. The ceramic has greater than 0.2 weight percent (w/o) magnesia, greater than 0.2 w/o yttria, where the sum of magnesia and yttria is less than 5 w/o. The ceramic has less than 0.2 v/o porosity. The tool (10) has a rake face (30) joined to flank faces (50) by cutting edges (70).