Patent ID: 7175798

Claim:
The method for the preparation of a cutting tool insert having a sintered alumina and silicon carbide whisker composite material body, comprising the steps of milling and mixing powders of alumina and silicon carbide whiskers; forming said mixture into a preformed workpiece; heating said workpiece at a heating rate of from about 20 to about 60° C. per minute by applying electrical energy in the form of a DC current that at least partially goes through said workpiece to a sintering temperature of between from 1800 to about 2300° C.; and holding said workpiece at said sintering temperature for a holding time of from about 5 to about 60 minutes at a pressure of between 20 to 100 MPa, wherein the proportion of silicon carbide whiskers in said composite material is from about 5 to about 50 % by volume and said alumina grain size in said composite material has a 80 th percentile (P 80 ) of less than 2.5 μm.