A cutting tool including a rake face and a flank face includes: a substrate; and a coating film disposed on the substrate, wherein the coating film includes an Al.sub.2O.sub.3 layer, residual stress of the Al.sub.2O.sub.3 layer has a minimum value R.sub.min at at least a portion of a region d1 of the rake face, the minimum value R.sub.min is more than −0.27 GPa and less than or equal to −0.1 GPa.

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 coated cutting tool has a substrate of cemented carbide, cermet, ceramics, steel or cubic boron nitride and a multi-layered wear resistant coating deposited thereon has a total thickness from 4 to 25 μm. The multi-layered wear resistant coating includes a TiAlCN layer (a) represented by the formula Ti1-xAlxCyNz with 0.2≤x≤0.97, 0≤y≤0.25 and 0.7≤z≤1.15 deposited by CVD, and a κ-Al.sub.2O.sub.3 layer (b) of kappa aluminium oxide deposited by CVD immediately on top of the TiAlCN layer (a). The Ti1-AlxCyNz layer (a) has an overall fiber texture with the {111} plane growing parallel to the substrate surface and a {111} pole figure, measured over an angle range of 0°≤α≤80° and the κ-Al2O3 layer (b) has an overall fiber texture with the {002} plane growing parallel to the substrate surface and a {002} pole figure, over an angle range of 0°≤α≤80°.

A coated cutting tool includes a multilayer of alternating sublayers of κ-Al.sub.2O.sub.3 and sublayers of TiN, TiC, TiCN, TiCO or TiCNO. The multilayer includes at least 3 sublayers of κ-Al.sub.2O.sub.3. The multilayer further exhibits an XRD diffraction over a θ-2θ scan of 15°-140°, wherein the 0 0 2 diffraction peak (peak area) is the strongest peak originating from the κ-Al.sub.2O.sub.3 sublayers of the multilayer.

A piston ring with a coated outer surface is provided. The coating is disposed on end sections of the outer surface adjacent a gap. Typically, a middle section of the outer surface located between the end sections is not coated. The coating can be formed of CrN or DLC, and the CrN coating can be applied by physical vapor deposition (PVD). The end sections of the outer surface, upon which the coating is applied, are rough. For example, the outer surface can be blasted or otherwise textured to achieve the rough surface. The rough surface retains oil and distributes stress better than a smooth surface, and thus reduces crazing and flaking of the coating.

The present invention relates to a hard film having improved wear resistance and improved toughness. A hard film according to the present invention is formed by using a PVD method on a surface of a base material, wherein: the hard film includes a first hard layer and a second hard layer; the first hard layer has a thickness of approximately 0.1-3.0 μm and is composed of Ti.sub.1-aAl.sub.aN (0.3≤a≤0.7), and has a single phase structure; and the second hard layer has a thickness of approximately 0.5-10 μm and is composed of Ti.sub.1-a-bAl.sub.aMe.sub.bN (0.3≤a≤0.7, 0≤b≤0.05, the Me being at least one selected from V, Zr, Si, Nb, Cr, Mo, Hf, Ta and W); according to an XRD phase analysis method, a ratio ([200]/[111]) of the intensity of a [200] peak to the intensity of a [111] peak is approximately 1.5 or higher; the second hard layer preferentially grows in a [200] direction; the [200] peak is located at approximately 42.7°-44.6° and is composed of three phases, and the [111] peak is located at approximately 37.0°-38.5° and is composed of three phases; and when a peak having a largest intensity among the peaks of the three phases is a main peak and remaining peaks are sub-peaks, a ratio (main peak/sub-peaks) of the intensity of the main peak to the intensities of the sub-peaks in a [200] face is approximately 2 or higher, and a ratio (main peak/sub-peaks) of the intensity of the main peak to the intensities of the sub-peaks in a [111] face is approximately 2 or higher.

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 coated tool includes a base and a coating layer on the base. The coating layer includes a cubic crystal that includes one or more kinds of elements selected from Groups 4, 5 and 6 in the periodic table, Al, Si, B, Y and Mn, and one or more kinds of elements selected from C, N and O. A maximum peak is in a range of 50° or more in a distribution of X-ray intensity (111) at α axis of a pole figure, the X-ray intensity regarding a (111) plane of the cubic crystal. The intensity at the maximum peak is Imax, a peak width at 0.8 Imax of the maximum peak is 20° or more, and the intensity at 90° is 0.78 Imax or more. A cutting tool includes a holder which includes a pocket at an end, and the coated tool in the pocket.

A cutting tool including a rake face and a flank face includes: a substrate; and a coating film disposed on the substrate, wherein the coating film includes an Al.sub.2O.sub.3 layer, residual stress of the Al.sub.2O.sub.3 layer has a minimum value R.sub.min at at least a portion of a region f1 in the flank face, the minimum value R.sub.min is more than or equal to −0.25 GPa and less than or equal to −0.1 GPa.

A coated cutting tool including a substrate and a coating is provided. The coating includes a nano-multilayer of alternating layers of a first nanolayer being Ti.sub.1-xAl.sub.xN, 0.35≤x≤0.70, and a second nanolayer being Ti.sub.1-yAl.sub.yN, 0.12≤y≤0.25. A sequence of one first nanolayer and one second nanolayer forms a layer period. The average layer period thickness in the nano-multilayer is ≤7 nm. The nanomultilayer has a columnar structure with an average column width of ≤70 nm.