A surface-coated cutting tool has a hard coating layer including an upper layer α, an adhesion layer β, and a lower layer γ. The upper layer α is formed of an α-Al.sub.2O.sub.3 layer formed under low temperature conditions. The adhesion layer β includes a TiCN layer having a thickness of 0.5 μm or more in an outermost layer and contains 0.5 to 3 μm to a maximum depth of 0.5 μm toward the inside in a layer thickness direction of the TiCN layer from the interface between the TiCN layer and the upper layer α. The lower layer γ is formed of (Ti.sub.1-XAl.sub.X)(C.sub.YN.sub.1-Y) of a single phase of a NaCl type face-centered cubic structure, in which an average content ratio X.sub.avg of Al and an average content ratio Y.sub.avg of C in this composition formula satisfy 0.60≤X.sub.avg≤0.95 and 0≤Y.sub.avg≤0.005.

A coated tool includes a base and a coating layer located on the base. The coating layer includes a first layer having a thickness of 1 μm or more located near the base, and a second layer including Al.sub.2O.sub.3 particles which is in contact with the first layer and is located more away from the base than the first layer. A difference (A2−A1) between an erosion ratio A2 in the second layer and an erosion ratio A1 in the first layer is 0.60 to −0.30 μm/g. The erosion ratio is obtained by collision of a liquid A in which 3 mass % of spherical Al.sub.2O.sub.3 particles having a mean particle diameter of 1.1-1.3 μm is dispersed in pure water. A cutting tool includes a holder which includes a pocket, and the coated tool located in the pocket.

A coated tool includes a base and a coating layer located on the base. The coating layer includes a first layer having a thickness of 1 μm or more located near the base, and a second layer located more away from the base than the first layer. An erosion ratio A2 in the second layer is 0.4 μm/g or less which is obtained from a measurement by collision of a liquid A, in which 3 mass % of spherical Al.sub.2O.sub.3 particles having a mean particle diameter of 1.1-1.3 μm is dispersed in pure water, against the second layer. An erosion ratio A1 in the first layer is 1.8 μm/g or less which is obtained from a measurement by collision of the liquid A against the first layer. A cutting tool includes a holder which includes a pocket, and the coated tool located in the pocket.

Provided is a ceramic sintered body having high wear resistance and chipping resistance. Also provided are an insert, a cutting tool and a friction stir welding tool, each of which uses such a high-performance ceramic sintered body. The ceramic sintered body includes Al.sub.2O.sub.3 (alumina), WC (tungsten carbide) and ZrO.sub.2 (zirconia), wherein Zr (zirconium) element is present at either one or both of: (1) a grain boundary between crystal grains of the Al.sub.2O.sub.3; and (2) a grain boundary of crystal grains of the Al.sub.2O and crystal grains of the WC, wherein the ceramic sintered body contains 55.0 to 97.5 vol % of the WC, 0.1 to 18.0 vol % of the ZrO.sub.2, and the balance being the Al.sub.2O.sub.3, and wherein the ZrO.sub.2 is in a phase of tetragonal structure (T) or a mixed phase of tetragonal structure (T) and monoclinic structure (M).

A coated cutting tool comprising: a substrate; and a coating layer formed on a surface of the substrate, wherein: the coating layer comprises a lower layer, an intermediate layer and an upper layer in this order from the substrate side; the lower layer comprises one or more Ti compound layers containing a Ti compound of Ti and an element of at least one kind selected from the group consisting of C, N, O and B; and the intermediate layer comprises an α-Al.sub.2O.sub.3 layer containing α-Al.sub.2O.sub.3; and the upper layer comprises a TiCN layer containing TiCN; an average thickness of the coating layer is within a specific range, and an average thickness of the upper layer is within a specific range; in a cross section perpendicular to the surface of the substrate, the grains in the TiCN layer constituting the upper layer satisfies a specific condition.

A cutting tool includes: a substrate; a hard layer provided on the substrate; and a titanium carbonitride layer provided on the hard layer, wherein a thickness of the titanium carbonitride layer is more than or equal to 2 μm, a hardness of the titanium carbonitride layer at a room temperature is more than or equal to 35 GPa, and a Young's modulus of the titanium carbonitride layer at the room temperature is more than or equal to 800 GPa.

A cemented carbide includes first hard phase grains, second hard phase grains, third hard phase grains, and a metal binder phase, wherein the cemented carbide has a total of 70 unit regions, the number of unit regions each having a percentage of less than 0.43% or more than 2.43% is ≤10 among the total of 70 unit regions, the percentage being a percentage of the total number of the second and the third hard phase grains in each unit region with respect to the total number of the second and the third hard phase grains in the total of 70 unit regions, and in a total of 10 unit regions existing in a fourth row in a longitudinal direction, a percentage of the number of the third hard phase grains with respect to the total number of the second and the third hard phase grains is 5% to 15%.

Provided is a coated cutting tool, which includes a hard coating film containing a layer (b) formed of a nitride or a carbonitride, a layer (c) which is a layered coating film formed by alternately layering a nitride or carbonitride layer (c1) that contains 55 atom % or more and 75 atom % or less of Al, Cr having a second highest content percentage, and at least Si and a nitride or carbonitride layer (c2) that contains 55 atom % or more and 75 atom % or less of Al and Ti having a second highest content, and a layer (d) that is a nitride or carbonitride that contains, with respect to a total amount of metal elements (including metalloid elements), 55 atom % or more and 75 atom % or less of Al and Ti having a second highest content percentage, the content percentage of Ti being 20 atom % or more.

The present invention relates to a cutting tool, which performs, like a drill or a ball end mill, cutting while rotating in a state in which the center of the tip end is in contact with a work material, and includes a wear-resistant layer formed at the tip end thereof, wherein a portion of the wear-resistant layer is selectively removed through tip end polishing from the center of the tip end of the drill or the ball end mill to a predetermined area, so as to restrain micro-brittle wear generated in an ultra-low speed region, and thus remarkably improving the cutting lifespan of the cutting tool such as the drill or the ball end mill.

A cBN sintered material cutting tool includes a cutting tool body that is made of a sintered material including cubic boron nitride particles and a binder phase, in which: an average particle size of the cBN particles is 0.5 μm or less and a content ratio of the cBN particles in the sintered material is 35 vol % to 80 vol %; and the binder phase includes 1.0 vol % to 20 vol % of an Al compound, an average particle size of the Al compound present in the binder phase is 300 nm or less, and a value of a ratio (a value of S.sub.N/S.sub.O; area ratio) of a content S.sub.N of nitrogen (N) included in the Al compound to a content S.sub.O of oxygen (O) included in the Al compound is 1.1 to 5.