Abstract: A cutting tool includes: a base metal provided with a seat portion; a blade edge member that is a polycrystalline diamond sintered material containing polycrystalline diamond and a binder; and a brazing material that fixes the blade edge member to the seat portion of the base metal. The blade edge member has a thickness of greater than or equal to 0.3 mm. The brazing material is disposed between a blade edge bottom face of the blade edge member and a seat bottom face of the seat portion and is in contact with the blade edge bottom face and the seat bottom face. The flank face is located outside of the base metal with respect to the lateral face of the base metal.

Abstract: A composite sintered material includes: a plurality of diamond grains having an average grain size of less than or equal to 10 ?m; a plurality of cubic boron nitride grains having an average grain size of less than or equal to 2 ?m; and a plurality of aluminum oxide grains having an average grain size of less than or equal to 0.5 ?m; and a remainder of a binder phase, wherein at least parts of adjacent diamond grains are bound to one another, the binder phase includes cobalt, in the composite sintered material, a content of the diamond grains is from 30 to 92 volume %, a content of the cubic boron nitride grains is from 3 to 40 volume %, a content of the aluminum oxide grains is from 2 to 15 volume %, and a content of the cobalt is from 3 to 30 volume %.

Abstract: A cutting tool includes a rake face, a flank face, and a cutting edge ridge line connecting the rake face and the flank face. A portion of the rake face and a portion of the flank face adjacent to the cutting edge ridge line are made of a diamond sintered body including diamond grains. A dislocation density in the portion of the flank face is 8×1015/m2 or less. The diamond grains have an average grain size of 0.1 ?m to 50 ?m. A content ratio of the diamond grains in the diamond sintered body is 80% by volume to 99% by volume.

Abstract: A rotary cutting tool according to the present disclosure is rotatable about an axial line and includes a rake face and a flank face. The flank face is contiguous to the rake face. A ridgeline between the rake face and the flank face constitutes a cutting edge. In a cross section perpendicular to the axial line, the rake face is constituted of a plurality of straight line portions.

Abstract: A cutting tool according to the present disclosure has a rake face, a flank face, and a cutting edge. The cutting edge is located between the rake face and the flank face. The cutting tool includes a substrate composed of a cubic boron nitride sintered material, and an oxide layer that covers the substrate and that constitutes at least part or whole of the rake face, the flank face, and the cutting edge. The oxide layer includes at least one element selected from a group consisting of titanium, aluminum, zirconium, and cobalt. A thickness of the oxide layer is 2 ?m or less.

Abstract: A cubic boron nitride sintered material tool contains a plurality of cBN grains. cBN grains located on a surface of the cutting edge contain a cubic boron nitride phase, and a hexagonal boron nitride phase. When a ratio I?*/I?* between an intensity of a ?* peak derived from a ? bond of hBN in the hexagonal boron nitride phase and an intensity of a ?* peak derived from a ? bond of hBN in the hexagonal boron nitride phase and a ? bond of cBN in the cubic boron nitride phase is determined by measuring an energy loss associated with excitation of K-shell electrons of boron, the ratio I?*/I?* of the cBN grain on the surface of the cutting edge is 0.1 to 2, and the ratio I?*/I?* of the cBN grain at a depth position of 5 ?m from the surface of the cutting edge is 0.001 to 0.1.

Abstract: A cutting tool includes: a base metal provided with a seat portion; a blade edge member that is a polycrystalline diamond sintered material containing polycrystalline diamond and a binder; and a brazing material that fixes the blade edge member to the seat portion of the base metal. The blade edge member has a thickness of greater than or equal to 0.3 mm. The brazing material is disposed between a blade edge bottom face of the blade edge member and the a seat bottom face of the seat portion and is in contact with the blade edge bottom face and the seat bottom face. The flank face is located outside of the base metal with respect to the lateral face of the base metal.

Abstract: A composite sintered material includes a plurality of diamond grains, a plurality of cubic boron nitride grains, and a remainder of a binder phase, wherein the binder phase includes cobalt, a content of the cubic boron nitride grains in the composite sintered material is more than or equal to 3 volume % and less than or equal to 40 volume %, and an average length of line segments extending across continuous cubic boron nitride grains in appropriately specified straight lines extending through the composite sintered material is less than or equal to a length three times as large as an average grain size of the cubic boron nitride grains.

Abstract: A cutting tool rotates about a rotation axis, and includes a tip end portion. The tip end portion includes a partially spherical surface that is brought into contact with a workpiece. The surface is provided with a plurality of recesses disposed apart from each other. An opening edge of each of the plurality of recesses constitutes a cutting edge.

Abstract: A rotary cutting tool according to the present disclosure is rotatable about an axial line and includes a rake face and a flank face. The flank face is contiguous to the rake face. A ridgeline between the rake face and the flank face constitutes a cutting edge. In a cross section perpendicular to the axial line, the rake face is constituted of a plurality of straight line portions.