Silicon nitride ceramics and cutting tools made therefrom (SILICON NITRIDE CERAMIC AND CUTTING TOOL MADE THEREOF)

摘要

There is provided a silicon nitride main component ceramic which is particularly useful for use as cutting tool 10 in high speed chip forming machining of metal materials. The ceramic preferably comprises at least 85 volume percent (v / o) of a beta silicon nitride phase and about 5 v / o or less of an intergranular phase. The ceramic contains 0.2 weight percent (w / o) or more of magnesium oxide and 0.2 w / o or more yttrium oxide, and the sum of magnesium oxide and yttrium oxide is 5 w / o or less. The ceramic has a processing degree of 0.2 v / o or less. The tool 10 has a rake face 30 joined to the flank faces 50 by a cutting edge 70.