CUBIC BORON NITRIDE SINTERED BODY AND CUBIC BORON NITRIDE SINTERED BODY TOOL

摘要

The purpose of the present invention is to obtain a cubic boron nitride sintered body having both excellent defect resistance and abrasion resistance and having a high cubic boron nitride content. The cubic boron nitride sintered body of the present invention comprises cubic boron nitride and a bonding phase. In the cubic boron nitride sintered body the content of cubic boron nitride is within the range of no less than 82 volume percent to no more than 98 volume percent. In the cross section of the cubic boron nitride sintered body an isolated bonding phase having an area in the range of no less than 0.05µm2 to no more than 0.5 µm2 has a protrusion of at least two levels into the cubic boron nitride. If the length of the side perpendicular to the tip direction of the first level of the protrusion from the tip of the protrusion is A1, the parallel side length is B1, the length of the side perpendicular to the tip direction of the second level of the protrusion from the tip of the protrusion in the tip direction is A2 and the parallel side length is B2, the surface area ratio of an isolated bonding phase having a protrusion in which A1/B1 are at least 1 and no more than 10 times A2/B2 is at least 25% of the entire bonding phase that has a surface area within the range of no less than 0.05µm2 to no more than 0.5 µm2.