A hard coating includes a three kinds of layers that are alternately laminated. The three kinds of layers consist of a single composition layer and two kinds of nanolayer-alternated layers. The single composition layer is constituted by one of an A composition (nitride of AlCrSiα), a B composition (nitride of CrBSiβ) and a C composition (nitride of AlCr(SiC)γ). The two kinds of nanolayer-alternated layers include nanolayers which are alternately laminated and which are constituted by two of three combinations consisting of a combination of the A composition and B composition, a combination of the A composition and C composition and a combination of the B composition and C composition. The single composition layer has a thickness of 0.5-1000 nm. Each of the nanolayers constituting the two kinds of nanolayer-alternated layers has a thickness of 0.5-500 nm, and each of the two kinds of nanolayer-alternated layers has a thickness of 1-1000 nm.

A cutting tool includes a base body and a coating applied thereto. For providing a cutting tool, having both a hard coating that also exhibits fracture toughness, the coating includes at least one oxide layer deposited in the PVD process, consisting of at least 10 alternating single coats of Al.sub.2O.sub.3 and (Al.sub.x,Me.sub.1-x).sub.2O.sub.3, where 0<x<1, wherein Me is selected from one or more of the group of Si, Ti, V, Zr, Mg, Fe, B, Gd, La and Cr.

In a vanadium nitride film formed on a surface of a base material, a ratio V [at %]/N [at %] between a vanadium element concentration and a nitrogen element concentration in the film is 1.08 or more and a chlorine element concentration in the film is 1 at % or more and 5 at % or less.

A method of producing a cubic boron nitride sintered material includes: forming an organic cubic boron nitride powder by attaching an organic substance onto a cubic boron nitride source material powder; preparing a powder mixture including more than or equal to 85 volume % and less than 100 volume % of the organic cubic boron nitride powder and a remainder of a binder source material powder by mixing the organic cubic boron nitride powder and the binder source material powder, the binder source material powder including WC, Co and Al; and obtaining the cubic boron nitride sintered material by sintering the powder mixture.

A cutting tool, including a silicon nitride (Si.sub.3N.sub.4) ceramic substrate, and a diamond film coated on the surface of the Si.sub.3N.sub.4 ceramic substrate. The diamond film has a thickness of 7-12 μm. The cutting tool includes a tool nose, a blade, and a handle. The blade has a rake angle γ of 5-15°, a clearance angle α of 10-14°, and a helix angle of 15-45°. The blade includes four cutting edges.

A cutting tool comprises a substrate and a coating layer provided on the substrate, the coating layer including a multilayer structure layer composed of a first unit layer and a second unit layer, and a lone layer, the lone layer including cubic Ti.sub.zAl.sub.1-zN crystal grains, an atomic ratio z of Ti in the Ti.sub.zAl.sub.1-zN being 0.4 or more and less than 0.55, the lone layer having a thickness with an average value of 2.5 nm or more and 10 nm or less, the multilayer structure layer having a thickness with an average value of 10 nm or more and 45 nm or less, one multilayer structure layer and one lone layer forming a repetitive unit having a thickness with an average value of 20 nm to 50 nm, a maximum value of 40 nm to 60 nm, and a minimum value of 10 nm to 30 nm.

A cutting tool comprises a substrate and a coating layer provided on the substrate, the coating layer including a multilayer structure layer composed of a first unit layer and a second unit layer, and a lone layer, the lone layer including cubic Ti.sub.zAl.sub.1-zN crystal grains, an atomic ratio z of Ti in the Ti.sub.zAl.sub.1-zN being 0.55 or more and 0.7 or less, the lone layer having a thickness with an average value of 2.5 nm or more and 10 nm or less, the multilayer structure layer having a thickness with an average value of 40 nm or more and 95 nm or less, one multilayer structure layer and one lone layer forming a repetitive unit having a thickness with an average value of 50 nm to 100 nm, a maximum value of 90 nm to 110 nm, and a minimum value of 40 nm to 60 nm.

A cutting tool comprises a substrate and a coating layer provided on the substrate, the coating layer including a multilayer structure layer composed of a first unit layer and a second unit layer, and a lone layer, the lone layer including cubic Ti.sub.zAl.sub.1-zN crystal grains, an atomic ratio z of Ti in the Ti.sub.zAl.sub.1-zN being 0.4 or more and less than 0.55, the lone layer having a thickness with an average value of 2.5 nm or more and 10 nm or less, the multilayer structure layer having a thickness with an average value of 40 nm or more and 95 nm or less, one multilayer structure layer and one lone layer forming a repetitive unit having a thickness with an average value of 50 nm to 100 nm, a maximum value of 90 nm to 110 nm, and a minimum value of 40 nm to 60 nm.

A cutting tool comprises a substrate and a coating layer provided on the substrate, the coating layer including a multilayer structure layer composed of a first unit layer and a second unit layer, and a lone layer, the lone layer including cubic Ti.sub.zAl.sub.1-zN crystal grains, an atomic ratio z of Ti in the Ti.sub.zAl.sub.1-zN being 0.5 or more and 0.65 or less, the lone layer having a thickness with an average value of 2.5 nm or more and 10 nm or less, the multilayer structure layer having a thickness with an average value of 10 nm or more and 95 nm or less, one multilayer structure layer and one lone layer forming a repetitive unit having a thickness with an average value of 30 nm to 70 nm, a maximum value of 40 nm to 100 nm, and a minimum value of 20 nm to 40 nm.

In a hard-film-coated drill having a cemented carbide drill body coated with a hard film, the drill body is provided with a smooth region at a boundary between a flank surface and a rake surface. The surface hardness of the hard film is within 2000 to 2500 HV in Vickers hardness. A radius r1 (μam) of curvature of the first ridgeline L1 where the smooth region and the flank surface intersect is represented by r1=0.45×D+a1 (10≤a1≤25), where D is the diameter (mm) of the body. A radius r2 (μm) of curvature the second ridgeline L2 where the flank surface and a margin intersect is represented by r2=0.65×D+a2 (39≤a2≤67). A thickness t1 (μm) of the hard film is represented by t1=0.8×ln(D)+a3 (0.7≤a3≤3.0).