A cutting tool comprises a substrate and a coating that coats the substrate, the coating including an α-alumina layer provided on the substrate, the α-alumina layer including crystal grains of α-alumina, the α-alumina layer including a lower portion and an upper portion, the upper portion being occupied in area at a ratio of 50% or more by crystal grains of α-alumina having a (006) plane with a normal thereto having a direction within ±15° with respect to a direction of the normal to the second interface, the lower portion being occupied in area at a ratio of 50% or more by crystal grains of α-alumina having a (110) plane with a normal thereto having a direction within ±15° with respect to the direction of the normal to the second interface, the α-alumina layer having a thickness of 3 μm or more and 20 μm or less.

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.

A coated cutting tool includes a substrate and a coating layer formed onto the surface of the substrate. The coating layer contains an outermost layer. The outermost layer contains NbN. The NbN contains cubic NbN and hexagonal NbN. When a peak intensity at a (200) plane of cubic NbN is made I.sub.c, a peak intensity at a (101) plane of the hexagonal NbN is made I.sub.h1, and a sum of peak intensities at a (103) plane and a (110) plane of the hexagonal NbN is made I.sub.h2 in X-ray diffraction analysis, a ratio [I.sub.h1/(I.sub.h1+I.sub.c)] of I.sub.h1 based on a sum of I.sub.c and I.sub.h1 is 0.5 or more and less than 1.0, and a ratio [I.sub.h1/(I.sub.h1+I.sub.h2)] of I.sub.h1 based on a sum of I.sub.h1 and I.sub.h2 is 0.5 or more and 1.0 or less.

A surface-coated cutting tool has a hard coating layer and a tool body, which is coated with a lower layer including a TiCN layer having at least an NaCl type face-centered cubic crystal structure and an upper layer formed of a TiAlCN layer having a single phase crystal structure of NaCl type face-centered cubic crystals or a mixed phase crystal structure of NaCl type face-centered cubic crystals and hexagonal crystals. The tool body is further coated with an outermost surface layer including an Al.sub.2O.sub.3 layer, when the layer of a complex nitride or complex carbonitride of Ti and Al is expressed by the composition formula: (Ti.sub.1-xAl.sub.x)(C.sub.yN.sub.1-y), the average amount Xave of Al in Ti and Al and the average amount Yave of C in C and N (both Xave and Yave are atomic ratios) respectively satisfy 0.60≦Xave≦0.95 and 0≦Yave≦0.005.

A turbomachine component having a main body and a multilayer coating, which is applied directly to the main body is provided. The multilayer coating is at least 5 μm and at most 35 μm thick and has a plurality of layers applied directly one on top of the other, wherein the layer applied directly to the main body is an adhesion promoting layer, which comprises chromium nitride, and at least one of the remaining layers comprises a hard material.

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.

A coated cutting tool includes a substrate of cemented carbide, cermet, ceramics, steel or cubic boron nitride and a multi-layered wear resistant coating. The multi-layered wear resistant coating has a total thickness from 5 to 25 μm and includes refractory coating layers deposited by chemical vapour deposition (CVD) or moderate temperature chemical vapour deposition (MT-CVD). The multi-layered wear resistant coating has at least one pair of layers (a) and (b), with layer (b) being deposited immediately on top of layer (a). Layer (a) is a layer of aluminium nitride having hexagonal crystal structure (h-AlN) and a thickness from 10 nm to 750 nm. Layer (b) is a layer of titanium aluminium nitride or titanium aluminium carbonitride represented by the general formula Ti.sub.1-xAl.sub.xC.sub.yN.sub.z with 0.4≤x≤0.95, 0≤y≤0.10 and 0.85≤z≤1.15, having a thickness from 0.5 μm to 15 μm, and at least 90% of the Ti.sub.1-xAl.sub.xC.sub.yN.sub.z of layer (b) has a face-centered cubic (fcc) crystal structure.

The hard coating layer includes at least a complex nitride or carbonitride layer (2) expressed by a composition formula: (Ti.sub.1-x-yAl.sub.xMe.sub.y)(C.sub.zN.sub.1-z), Me being an element selected from Si, Zr, B, V, and Cr. The average content ratio X, the average content ratio Y, and the average content ratio Z satisfy 0.60≦x.sub.avg, 0.005≦y.sub.avg≦0.10, 0≦z.sub.avg≦0.005, and 0.605≦x.sub.avg+y.sub.avg≦0.95. There are crystal grains having a cubic structure in the crystal grains constituting the complex nitride or carbonitride layer (2). A predetermined periodic content ratio change of Ti, Al and Me exists in the crystal grains having the cubic structure.

A surface-coated cutting tool includes a base material and a coating formed on the base material. The coating includes an α-Al.sub.2O.sub.3 layer. The α-Al.sub.2O.sub.3 layer contains a plurality of α-Al.sub.2O.sub.3 crystal grains and a plurality of κ-Al.sub.2O.sub.3 crystal grains, and has a TC(006) of more than 5 in a texture coefficient TC(hkl). A ratio of C.sub.κ to a sum of C.sub.α and C.sub.κ: [C.sub.κ/(C.sub.α+C.sub.κ)×100](%) is 0.05 to 7%, where C.sub.α is a total number of peak counts of the α-Al.sub.2O.sub.3 crystal grains obtained from measurement data of x-ray diffraction for the coating, and C.sub.κ is a total number of peak counts of the κ-Al.sub.2O.sub.3 crystal grains obtained from the measurement data of the x-ray diffraction for the coating.

A coating system disposed on a surface of a substrate is provided. The coating system includes a bond coating on the surface of the substrate, a protective coating on the bond coating, a thermal barrier coating on the protective coating, and a protective agent disposed within at least some of the voids of the thermal barrier coating. The protective coating is constructed from a ceramic material, and the thermal barrier coating defines a plurality of elongated surface-connected voids. Methods are also generally provided for forming such a coating system.