A coated cutting tool including a substrate and a coating layer formed on the substrate, wherein the coating layer has an alternately laminated structure of a first layer and a second layer, the first layer contains a compound having a composition represented by (Al.sub.aTi.sub.1-a)N (0.80 ≤ a ≤ 0.95), the second layer contains a compound having a composition represented by (Al.sub.bM.sub.cTi.sub.1-b-c)N (M represents at least one of Si or B, 0.80 ≤ b ≤ 0.95, and 0 < c ≤ 0.20), a and b satisfy |a-b| ≤ 0.05, and an average thickness of the alternately laminated structure is 1.0 .Math.m or more and 10.0 .Math.m or less.

A coated cutting tool includes a substrate with a rake side, a clearance side and a cutting edge, and a coating including a first layer and a second layer. The second layer includes an inner layer and an outer layer, wherein the first layer is exposed through an opening in the inner layer and the opening extends over at least a portion of the width of the cutting edge. Thereby, a double layer is provided in critical areas, whereas a single layer is provided in other areas. Preferably, the double oxide layer includes aluminum oxide layers. A method for manufacturing the coated cutting tool is also provided.

A surface-coated boron nitride sintered body tool is provided, in which at least a cutting edge portion includes a cubic boron nitride sintered body and a coating film formed on a surface of the cubic boron nitride sintered body. The coating film includes an A layer and a B layer. The A layer is formed of columnar crystals each having a particle size of 10 nm or more and 400 nm or less. The B layer is formed of columnar crystals each having a particle size of 5 nm or more and 70 nm or less. The B layer is formed by alternately stacking two or more compound layers having different compositions. The compound layers each have a thickness of 0.5 nm or more and 300 nm or less.

A cutting tool comprising a base material and a coating arranged on the base material; wherein: the coating comprises an α-Al.sub.2O.sub.3 layer composed of a plurality of α-Al.sub.2O.sub.3 particles; the average particle diameter a of the α-Al.sub.2O.sub.3 particles in a first region of the α-Al.sub.2O.sub.3 layer is 0.10 μm or more and 0.30 μm or less; the average particle diameter b of the α-Al.sub.2O.sub.3 particles in a second region of the α-Al.sub.2O.sub.3 layer is 0.30 μm or more and 0.50 μm or less; the average particle diameter c of the α-Al.sub.2O.sub.3 particles in a third region of the α-Al.sub.2O.sub.3 layer is 0.30 μm or more and 0.50 μm or less; and the ratio b/a is 1.5 or more and 5.0 or less.

A coated tool, such as a rotating, cutting tool, includes a tool body and a multilayer wear protection coating system. The wear protection system coats a functional surface of the tool body that is subject to wear and includes a first undoped diamond layer and a second undoped diamond layer disposed over the first undoped diamond layer. The first undoped diamond layer is electrically conductive and exhibits grain boundary conductivity from delocalized electrons. The second undoped diamond layer is electrically insulating. The first undoped diamond layer is 4-20 microns thick and is made with diamond grains whose size ranges from 4-10 nm. The first and second diamond layers are applied by chemical vapor deposition (CVD) using a hot-wire method. The wear protection system also includes an additional undoped diamond layer that is electrically insulating and is disposed between the functional surface of the tool body and the first diamond layer.

A coating on a substrate is disclosed having layers including yttrium aluminum garnet (YAG) and yttrium aluminum monoclinic (YAM).

A polycrystalline diamond is formed on a substrate to form a polycrystalline diamond compact (PDC) cutter for a tool. The polycrystalline diamond has a cross-sectional dimension of at least 4 millimeters. The substrate includes tungsten carbide. An outer surface of the PDC cutter is at least partially surrounded with at least a single layer of coating by atomic layer deposition. The single layer of coating is configured to protect the PDC cutter from thermal degradation in response to exposure to a temperature greater than 700 degrees Celsius (° C.) and less than about 1050° C.

A coated cutting tool for chip forming machining of metals includes a substrate having a surface coated with a chemical vapour deposition (CVD) coating. The coated cutting tool has a substrate coated with a coating including a layer of α-Al2O3, wherein the α-Al2O3 layer exhibits a dielectric loss of 10−6≦tan δ≦0.0025, as measured with AC at 10 kHz, 100 mV at room temperature of 20° C.

A surface-coated cutting tool with a hard coating layer is provided. The hard coating layer includes at least a complex nitride or carbonitride layer (2) expressed by a composition formula: (Ti.sub.1-x-yAl.sub.xMe.sub.y)(C.sub.zN.sub.1-z), Me being an element selected from Si, Zr, B, V, and Cr. The average content ratio X.sub.avg, the average content ratio Y.sub.avg, and the average content ratio Z.sub.avg satisfy 0.60≦X.sub.avg, 0.005≦Y.sub.avg≦0.10, 0≦Z.sub.avg≦0.005, and 0.605≦x.sub.avg+y.sub.avg≦0.95. There are crystal grains having a cubic structure in the crystal grains constituting the complex nitride or carbonitride layer (2). A predetermined periodic content ratio change of Ti, Al and Me exists in the crystal grains having the cubic structure.

A coated tool according to the present disclosure comprises a base body and a coating film. The base body is made of a cemented carbide or a cermet. The coating film is located on the base body. In a case where a hardness is measured by pressing an indenter from a surface of the coating film to a depth of 20% of the coating film while changing an indentation load of the indenter, when a minimum hardness of the hardness is defined as a first hardness, a maximum hardness of the hardness is defined as a second hardness, a depth at the first hardness is defined as a first hardness depth, and a depth at the second hardness is defined as a second hardness depth, the second hardness depth is smaller than the first hardness depth, and a difference therebetween is greater than 7 GPa.