A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, the MAlN layer including crystal grains of M.sub.xAl.sub.1-xN in the cubic crystal system, n.sub.F<n.sub.R being satisfied, where n.sub.F represents a number of voids per 100 μm in length of the MAlN layer on the flank face in a cross section of the MAlN layer, and n.sub.R represents a number of voids per 100 μm in length of the MAlN layer on the rake face in a cross section of the MAlN layer, n.sub.D being 3 or less, where n.sub.D represents a number of droplets per 100 μm in length of the MAlN layer on the flank face in a cross section of the MAlN layer.

In a surface-coated cutting tool, an A layer made of an (Al.sub.1-xTi.sub.x)N layer (0.35≦x≦0.6 by an atom ratio) and a B layer made of a (Al.sub.1-y-zTi.sub.ySi.sub.z)N layer (0.35≦y≦0.6 and 0.01≦z≦0.1 by an atom ratio) are layered on a surface of a tool body in which at least a cutting edge is made of a cBN sintered body. A layer thickness ratio of the A layer and the B layer (t.sub.B/t.sub.A) is 2 to 5, an X-ray diffraction intensity ratio I(200)/I(111) as the entire hard coating layer is more than 3 and 12 or less, a full width at half maximum of a peak of I(200) is 0.3 to 1.0, the I.sub.A(200)/I.sub.A(111) of the A layer is 2 to 10, and a full width at half maximum of the peak of the I.sub.A(200) is 0.3 to 1.0.

In a surface-coated cutting tool, an A layer made of an (Al.sub.1-xTi.sub.x)N layer (0.35≦x≦0.6 by an atom ratio) and a B layer made of a (Al.sub.1-y-zTi.sub.ySi.sub.z)N layer (0.35≦y≦0.6 and 0.01≦z≦0.1 by an atom ratio) are layered on a surface of a tool body in which at least a cutting edge is made of a cBN sintered body. A layer thickness ratio of the A layer and the B layer (t.sub.B/t.sub.A) is 2 to 5, an X-ray diffraction intensity ratio I(200)/I(111) as the entire hard coating layer is more than 3 and 12 or less, a full width at half maximum of a peak of I(200) is 0.3 to 1.0, the I.sub.A(200)/I.sub.A(111) of the A layer is 2 to 10, and a full width at half maximum of the peak of the I.sub.A(200) is 0.3 to 1.0.

A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, when a cross section of the MAlN layer is subjected to an electron backscattering diffraction image analysis to determine a crystal orientation of each of the crystal grains of the M.sub.xAl.sub.1−xN and a color map is created based thereon, then on the color map, the flank face having the MAlN layer occupied in area by 45% to 75% by crystal grains of the M.sub.xAl.sub.1−xN having a (111) plane with a normal thereto extending in a direction within 25 degrees with respect to a direction in which a normal to the flank face extends, the MAlN layer having a residual stress of −2 GPa to −0.1 GPa.

A cutting tool comprises a rake face and a flank face, the cutting tool being composed of a substrate made of a cubic boron nitride sintered material and a coating provided on the substrate, the coating including a MAlN layer, when a cross section of the MAlN layer is subjected to an electron backscattering diffraction image analysis to determine a crystal orientation of each of the crystal grains of the M.sub.xAl.sub.1−xN and a color map is created based thereon, then on the color map, the flank face having the MAlN layer occupied in area by 45% to 75% by crystal grains of the M.sub.xAl.sub.1−xN having a (111) plane with a normal thereto extending in a direction within 25 degrees with respect to a direction in which a normal to the flank face extends, the MAlN layer having a residual stress of −2 GPa to −0.1 GPa.

A surface-coated cutting tool according to the present invention includes a tool body and a hard coating layer including a complex carbonitride layer containing a small amount of chlorine and (Ti.sub.(1-x)Zr.sub.xyHf.sub.x(1-y))(N.sub.(1-z)C.sub.z) (0.10≤x≤0.90, 0<y≤1.0, 0.08<z<0.60), a ZrHf and C content ratios in cycles, a cycle distance between a maximum ZrHf content point and an adjacent minimum ZrHf content point and a cycle distance between a maximum C content point and an adjacent minimum C content point are 5 to 100 nm, an average value of content ratio differences Δx and Δz is 0.02 or more, a distance between the maximum ZrHf content point and the maximum C content point is ⅕ or less of the distance between a maximum content point and a minimum content point of adjacent ZrHf components, and a composition fluctuation structure is 10% or more.

A surface-coated cutting tool according to the present invention includes a tool body and a hard coating layer including a complex carbonitride layer containing a small amount of chlorine and (Ti.sub.(1-x)Zr.sub.xyHf.sub.x(1-y))(N.sub.(1-z)C.sub.z) (0.10≤x≤0.90, 0<y≤1.0, 0.08<z<0.60), a ZrHf and C content ratios in cycles, a cycle distance between a maximum ZrHf content point and an adjacent minimum ZrHf content point and a cycle distance between a maximum C content point and an adjacent minimum C content point are 5 to 100 nm, an average value of content ratio differences Δx and Δz is 0.02 or more, a distance between the maximum ZrHf content point and the maximum C content point is ⅕ or less of the distance between a maximum content point and a minimum content point of adjacent ZrHf components, and a composition fluctuation structure is 10% or more.

A coated cutting tool includes a body and a PVD coating disposed on the body. The body being cemented carbide, cermet, ceramics, polycrystalline diamond, polycrystalline cubic boron nitride based materials or a high speed steel. The coating includes a first layer of (Ti1-xAlx)N wherein 0.3≤x≤0.7, and a second layer of (Ti1-p-qAlp Siq)N with 0.15≤p≤0.45, and 0.05≤q≤0.20, wherein the second layer is deposited outside the first layer as seen in a direction from the body.

A cutting tool includes a base material, and a coating film covering the base material in contact with the base material. The base material is a cubic boron nitride sintered material. The coating film is a ceramic. An amount of oxygen in the coating film is less than or equal to 0.040 mass percent.

A cutting tool includes a base material, and a coating film covering the base material in contact with the base material. The base material is a cubic boron nitride sintered material. The coating film is a ceramic. An amount of oxygen in the coating film is less than or equal to 0.040 mass percent.