A composite sintered body cutting tool is made of a composite sintered body comprising a TiCN-based cermet layer; and a WC-based cemented carbide layer. The angle between the rake face and the flank face of the cutting tool is 90°. The rake face including a cutting edge of the cutting tool is constituted from the WC-based cemented carbide layer, in which 4 to 17 mass % of an iron group metal component and 75 mass % or more of W are included; and a major hard phase component is WC. The thickness of the WC-based cemented carbide layer is 0.05 to 0.3 times the thickness of the composite sintered body. The TiCN-based cermet layer is constituted from a single layer of a TiCN-based cermet layer, including at least, 4 to 25 mass % of an iron group metal component, less than 15 mass % of W, 2 to 15 mass % of Mo, 2 to 10 mass % of Nb and 0.2 to 2 mass % of Cr in a case where contents of the constituting components of the cermet layer are expressed as contents of metal components, and satisfy the Co content relative to the total content of Co and Ni of 0.5 to 0.8 with respect to Co and Ni of the iron group metal component in a mass ratio. When the height profile from the upper end to the lower end of the flank face is measured in the plane, which passes the center of the rake face of the cutting tool and is perpendicular to both of the rake face and the flank face, as the line, which passes the ridge line where the rake face and the flank face intersect and perpendicular to the rake face, being the reference line, the maximum elevation difference value of the height profile is in a ratio of 0.01 or less with respect to the thickness of the composite sintered body from the front surface of the rake face to a rear surface.

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.

A ceramic material includes of β-sialon (Si.sub.(6-z)Al.sub.zO.sub.zN.sub.(8-z)), polytype 15R, an intergranular phase, and yttrium. The polytype 15R includes twin grains.

In one aspect, sintered ceramic bodies are described herein which, in some embodiments, demonstrate improved resistance to wear and enhanced cutting lifetimes. For example, a sintered ceramic body comprises tungsten carbide (WC) in an amount of 40-95 weight percent, alumina in an amount of 5-30 weight percent and ditungsten carbide (W.sub.2C) in an amount of at least 1 weight percent.

A cermet and a cutting tool are provided which have high wear resistance and high fracture resistance at a cutting edge even in a mode of cutting where the cutting edge comes to have a high temperature. A cermet 1 includes a hard phase 2 including a carbonitride of one or more kinds of metals selected from Group 4, Group 5, and Group 6 metals of the periodic table including at least Ti and a binder phase 3 containing W and at least one kind of a metal selected from Co and Ni, wherein the binder phase 3 includes a first binder phase 4 in which a mass ratio of W to a total amount of Co and Ni (W/(Co+Ni)) is 0.8 or less and a second binder phase 5 in which a mass ratio of W to a total amount of Co and Ni (W/(Co+Ni)) is 1.2 or more.

The present disclosure provides a multilayer coated cutting material having increased wear resistance at high temperatures, a method for manufacturing the same, and a cutting tool insert for mechanical machining including the same. According to an embodiment of the present disclosure, the multilayer coated cutting material includes a cemented carbide, cermet, ceramic, a cubic crystal boron nitride-based material or a hard alloy body of high-speed steel, and a cutting layer positioned on the base material and configured in multiple layers.

In a surface-coated cutting tool in which a hard coating layer having a total layer thickness of 0.5 to 10 μm is deposited on a surface of a tool body made of WC-based cemented carbide or TiCN-based cermet, the hard coating layer has an alternately laminated structure of A layers and B layers, in a case where the A layer is: (Al.sub.aTi.sub.1-a)N (here, a is in atomic ratio), the A layer satisfies 0.50≦a<0.75, in a case where the B layer is: (Al.sub.bTi.sub.1-b)N (here, b is in atomic ratio), the B layer satisfies 0.75≦b≦0.95, and when a layer thickness per layer of the A layers is represented by x (nm) and a layer thickness per layer of the B layers is represented by y (nm), 5y≧x≧3y and 250 (nm)≧x+y≧100 (nm) are satisfied.

A surface-coated TiN-based cermet cutting tool is a surface-coated TiN-based cermet cutting tool, in which a TiN-based cermet containing a TiN phase as a hard phase component is used as a body, and a hard coating layer including a titanium carbonitride layer and an aluminum oxide layer is formed on a surface, in which a linear expansion coefficient of the TiN-based cermet is set to 9.0×10.sup.−6 (/K) or more, a thermal conductivity is set to 30 (W/m.Math.K) or more, and a residual compressive stress of the hard coating layer is set to 600 to 2,000 MPa, and particularly 600 to 2,000 MPa even in an as-deposited state by adjusting component composition and the like of the TiN-based cermet.

The present disclosure provides a multilayer coated cutting material having increased wear resistance at high temperatures, a method for manufacturing the same, and a cutting tool insert for mechanical machining including the same. According to an embodiment of the present disclosure, the multilayer coated cutting material includes a cemented carbide, cermet, ceramic, a cubic crystal boron nitride-based material or a hard alloy body of high-speed steel, and a cutting layer positioned on the base material and configured in multiple layers.

A cutting tool comprises a base material which includes particles including a tungsten carbide (WC) as a main component, a binder phase including cobalt (Co) as a main component, and particles including a carbide or a carbonitride of at least one selected from the group consisting of Group 4a, 5a, and 6a elements, or a solid solution thereof; and a hard film formed on the base material, wherein the hard film comprises at least an alumina layer, a cubic phase free layer (CFL), in which the carbide or the carbonitride is not formed, is formed from a surface of the base material to a depth of 10 μm to 50 μm, and a Co content of a surface of the CFL is 80% or more of a maximum Co content of the CFL.