Abstract: A cutting tool comprising a base material and a coating, wherein the coating includes a first layer having a multilayer structure in which a first unit layer and a second unit layer; a thickness of the first unit layer is 2 nm or more and less than 50 nm; a thickness of the second unit layer is 2 nm or more and less than 50 nm; a thickness of the first layer is 1.0 ?m or more and 20 ?m or less, the first unit layer is TiaAlbBcN, and the second unit layer is TidAleBfN, wherein 0.54?a?0.75, 0.24?b?0.45, 0<c?0.10, a+b+c=1.00, 0.44?d?0.65, -.34?e?0.55, 0<f?0.10, d+e+f=1.00, 0.05?a?d?0.20, and 0.05?e?b?0.20 are satisfied, and a percentage of the number of atoms of titanium to the total number of atoms of titanium, aluminum and boron is 50% or more in the first layer.

Abstract: A cutting tool comprising a base material and a coating, wherein the coating includes a first layer having a multilayer structure in which a first unit layer and a second unit layer are alternately stacked; a thickness of the first unit layer is 2 to 50 nm; a thickness of the second unit layer is 2 to 50 nm; a thickness of the first layer is 1.0 ?m or more and 20 ?m or less, the first unit layer is composed of TiaAlbBcN, and the second unit layer is composed of TidAleBfN, wherein 0.49?a?0.70, 0.19?0.40, 0.10<c?0.20, a+b+c=1.00, 0.39?d?0.60, 0.29?e?0.50, 0.10<f?0.20, d+e+f=1.00, 0.05?a?d?0.20, and 0.05?e?b?0.20 are satisfied, and a percentage of the number of atoms of titanium to the total number of atoms of titanium, aluminum and boron is 45% or more in the first layer.

Abstract: A polycrystalline cubic boron nitride comprising 99.5% by volume or more of cubic boron nitride, wherein the polycrystalline cubic boron nitride has a heat conductivity of 300 W/mK or more, the polycrystalline cubic boron nitride has a carbon content of 100 ppm or more and 1000 ppm or less in terms of mass, the polycrystalline cubic boron nitride comprises a plurality of crystal grains, and the plurality of crystal grains have a median diameter d50 of an equivalent circle diameter of 0.9 ?m or more and 10 ?m or less.

Abstract: A cutting tool includes a substrate and a hard layer, wherein the hard layer includes a first unit layer and a second unit layer being alternately layered in the hard layer, a thickness of the first unit layer is 2 to 100 nm, a thickness of the second unit layer is 2 to 100 nm, the first unit layer is composed of TiaAlbBcN, the second unit layer is composed TidAleBfN, an atomic ratio a satisfy 0.25?a<0.45, an atomic ratio b satisfy 0.55?b<0.75, an atomic ratio c satisfy 0<c?0.1, a total of the atomic ratios a, b and c is 1, an atomic ratio d satisfy 0.35?d<0.55, an atomic ratio e satisfy 0.45?e<0.65, an atomic ratio f satisfy 0<f?0.1, a total of the atomic ratios d, e and f is 1, the atomic ratios a and d satisfy 0.05?d?a?0.2, and the atomic ratios b and e satisfy 0.05?b?e?0.2.

Abstract: A diamond sintered material includes diamond grains, wherein a content ratio of the diamond grains is more than or equal to 80 volume % and less than or equal to 99 volume % with respect to the diamond sintered material, an average grain size of the diamond grains is more than or equal to 0.1 ?m and less than or equal to 50 ?m, and a dislocation density of the diamond grains is more than or equal to 8.1×1013 m?2 and less than 1.0×1016 m?2.

Abstract: A cutting tool, including a cutting edge portion composed of a cubic boron nitride sintered material, wherein the cutting edge portion has: a flank face; a rake face contiguous to the flank face; and a cutting edge positioned on a ridgeline of the flank face and the rake face, an arithmetical mean height Sa of the flank face is 0.5 ?m or more and 3.0 ?m or less, the Sa is measured in accordance with ISO25178-2:2012, and an oxygen concentration of the flank face is 10 mass % or more and 50 mass % or less.

Abstract: A cutting tool comprising a substrate and a coating film disposed on the substrate, wherein the coating film comprises a first layer; the first layer has a thickness of 0.2 ?m or more and 9 ?m or less; the first layer is composed of Ti(1-x-y)AlxMyN, wherein M is at least one element such as zirconium; in the first layer, x and y change along the thickness direction of the first layer; a maximum value of x, xmax, is 0.20 or more and 0.70 or less; a minimum value of x, xmin, is 0 or more and 0.6 or less; xmax and xmin satisfy 0.01?xmax?xmin?0.7; a maximum value of y, ymax, is 0.01 or more and 0.20 or less; a minimum value of y, ymin, is 0 or more and 0.19 or less; and ymax and ymin satisfy 0.01?ymax?ymin?0.2.

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 cubic boron nitride sintered material includes: more than or equal to 80 volume % and less than or equal to 96 volume % of cubic boron nitride grains; and a binder, wherein the binder includes tungsten carbide, cobalt, and an aluminum compound, and Ha/Hb?0.40 is satisfied, where Hb represents a hardness of the cubic boron nitride sintered material and Ha represents a hardness of the cubic boron nitride sintered material after performing acid treatment onto the cubic boron nitride sintered material to substantially remove the binder in the cubic boron nitride sintered material.

Abstract: A cutting insert includes a substrate and a cutting-edge insert. The substrate has, in a thickness direction of the substrate, a bottom surface, and a top surface opposite to the bottom surface. The top surface has a polygonal shape composed of a plurality of sides in a plan view as seen along the thickness direction. The top surface is provided with a projection projecting to a side opposite to the bottom surface along the thickness direction. The projection has a through-hole passing through the substrate along the thickness direction. The projection has a side surface contiguous to the top surface. The side surface is composed of a curved line protruding to a side opposite to the through-hole in the plan view as seen along the thickness direction.