CUTTING TOOL MADE OF CUBIC BORON NITRIDE-BASED SINTERED MATERIAL

摘要

A cutting tool made of cubic boron nitride-based sintered material that exhibits excellent chipping resistance and fracturing resistance in the intermittent cutting work on high hardness steel is provided. In the cutting tool, the average size of the cubic boron nitride particles is 0.5 to 8 µm. A portion of the cubic boron nitride particles are coated with aluminum oxide films having an average thickness of 10 to 90 nm on surfaces thereof, and a rift is partially formed in the aluminum oxide film. The average rift formation ratio satisfies the formula 0.02‰¦h/H‰¦0.08, wherein h is a breadth of the rift of the aluminum oxide film and H is a girth of the particle of cubic boron nitride.