A surface coated cutting tool comprises a base material and a coating layer that coats the base material, the coating layer including an alternate layer composed of a first unit layer and a second unit layer alternately stacked, the first unit layer being composed of a nitride containing aluminum and zirconium, in the first unit layer, when the total number of metal atoms constituting the first unit layer is represented as 1, a ratio thereto of the number of atoms of the zirconium being not less than 0.65 and not more than 0.95, the second unit layer being composed of a nitride containing titanium and aluminum, in the second unit layer, when the total number of metal atoms constituting the second unit layer is represented as 1, a ratio thereto of the number of atoms of the aluminum being larger than 0.40 and not more than 0.70.

A cutting tool including a rake face, a flank face, and a cutting edge portion, comprising a substrate and an AlTiN layer, the AlTiN layer including cubic Al.sub.xTi.sub.1-xN crystal grains, Al having an atomic ratio x of 0.7 or more and less than 0.95, the AlTiN layer including a central portion, the central portion at the rake face being occupied in area by (200) oriented Al.sub.xTi.sub.1-xN crystal grains at a ratio of 50% or more and less than 80%, the central portion at the cutting edge portion being occupied in area by (200) oriented Al.sub.xTi.sub.1-xN crystal grains at a ratio of 80% or more.

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 MAIN layer, the MAIN 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 m in length of the MAIN layer on the flank face in a cross section of the MAIN layer, and n.sub.R represents a number of voids per 100 m in length of the MAIN layer on the rake face in a cross section of the MAIN layer, n.sub.D being 3 or less, where n.sub.D represents a number of droplets per 100 m in length of the MAIN layer on the flank face in a cross section of the MAIN layer.

Provided is a surface-coated cutting tool including a base material and a coating including a super-multilayer-structure layer where A layers and B layers different from the A layers in composition are alternately laminated. The super-multilayer-structure layer includes an X area and a Y area those are alternately repeated. In the X area, A layers having a thickness A.sub.X and B layers having a thickness B.sub.X are alternately laminated. In the Y area, A layers having a thickness A.sub.Y and B layers having a thickness B.sub.Y are alternately laminated. The thickness A.sub.X is larger than the thickness A.sub.Y, and the thickness B.sub.X is smaller than the thickness B.sub.Y. Each of the A layers and the B layers comprising one or more elements selected from a group consisting of Ti, Al, Cr, Si, Ta, Nb, and W, and one or more elements selected from a group consisting of C and N.

A cutting tool comprising a substrate and a coating layer formed on the substrate, wherein the coating layer has, from a side closer to the substrate, a lower layer that contains a compound having a composition represented by (Al.sub.xTi.sub.1-x)N, and an upper layer that is formed on the lower layer and contains a compound having a composition represented by (Al.sub.yTi.sub.1-yN, the average thickness of the lower layer is 1.0 m or more and 10.0 m or less; the average thickness of the upper layer is 1.0 m or more and 10.0 m or less; and an area ratio GOS.sub.i of crystal grains having a GOS value of 1 degree or lower in the lower layer and an area ratio GOS.sub.s of crystal grains having a GOS value of 1 degree or lower in the upper layer satisfy GOS<GOS.sub.s.

A cutting blade having a plurality of different coatings on surfaces thereof, including an upper surface, a lower surface, and a side surface connecting the upper surface and the lower surface, wherein the upper surface intersects the side surface to form at least one cutting edge unit, the cutting edge unit includes a main cutting edge and a secondary cutting edge, the upper surface includes at least one set of cutting planes, the cutting planes include a main cutting surface and a secondary cutting surface, the main cutting surface intersects the side surface to form the main cutting edge, the secondary cutting surface intersects the side surface to form the secondary cutting edge, a main coating is provided on the main cutting surface, a secondary coating is provided on the secondary cutting surface, and the main coating and the secondary coating are independent from each other.

A coated cutting tool including a substrate and a coating layer formed on the substrate, wherein the coating layer comprises 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.aM.sub.bTi.sub.1-a-b)N (M represents at least one of a Nb element and a Ta element, and 0.75a0.90 and 0.00<b0.20 are satisfied), the second layer contains a compound having a composition represented by (Al.sub.cM.sub.dTi.sub.1-c-d)N (M represents at least one of a Nb element and a Ta element, and 0.75c0.90 and 0.00d0.20 are satisfied), at least one of a and c is 0.80 or more, and the average thickness of the alternately laminated structure is 0.5 m or more and 5.0 m or less.

A surface coated cutting tool having surfaces including a rake face and a flank face and a cutting edge defined by a boundary portion between the rake face and the flank face includes a substrate and a coating which covers the surfaces of the substrate, the coating having a TiAlN layer having an NaCl type crystal structure, and relation of 0.65<XR0.9, 0.65<XF0.9, 0.4XE0.7, XRXE0.2, and XFXE0.2 being satisfied, with a composition of the TiAlN layer in a cutting edge region located in the cutting edge being expressed as Ti.sub.1-XEAl.sub.XEN, a composition thereof in a rake face region located in the rake face being expressed as Ti.sub.1-XRAl.sub.XRN, and a composition thereof in a flank face region located in the flank face being expressed as Ti.sub.1-XFAl.sub.XFN.

A cutting edge tip of a cubic boron nitride sintered body has improved joint strength to a substrate of a cemented carbide. A cutting edge tip of a cubic boron nitride sintered body has improved crater wear resistance. A tool 10 of the present invention includes a substrate 12 of a cemented carbide and a cutting edge tip 14 of a cubic boron nitride sintered body joined to the substrate 12. The cutting edge tip 14 has a thickness covering an upper surface 12a to a lower surface 12b of the substrate 12. The cubic boron nitride sintered body contains 50 volume % or more and 95 volume % or less of cubic boron nitride and 5 volume % or more and 50 volume % or less of a binder phase. The cubic boron nitride has an average grain size of 1.0 m or more and 6.0 m or less.

A cutting tool is a cutting tool comprising a substrate and a coating film disposed on the substrate, in which the coating film includes a first layer, the first layer is composed of an alternate layer where a first unit layer and a second unit layer are alternately stacked, the first unit layer is composed of Ti.sub.1-a-bAl.sub.aCe.sub.bN, a is 0.350 or more and 0.650 or less, b is 0.001 or more and 0.100 or less, the second unit layer is composed of Al.sub.cCr.sub.1-cN, c is 0.40 or more and 0.75 or less, and a and c satisfy a relationship of c>a.