A coated cutting tool includes a substrate of cemented carbide, cermet, ceramics, steel or cubic boron nitride, a multi-layered wear resistant coating and at least two refractory coating layers deposited. The at least two refractory coating layers include a first coating layer and a second coating layer deposited on top of each other. The first coating layer is titanium aluminium nitride or carbonitride Ti.sub.1-uAl.sub.uC.sub.vN.sub.w, with 0.2≦u≦1.0, 0≦v≦0.25 and 0.7≦w≦1.15 deposited by CVD. The second coating layer is titanium carbonitride Ti.sub.xC.sub.yN.sub.1-y, with 0.85≦x≦1.1 and 0.4≦y≦0.85, and is deposited on top of the first coating layer by MT-CVD. The second Ti.sub.xC.sub.yN.sub.1-y coating layer has a columnar grain morphology and the overall fiber texture of the Ti.sub.xC.sub.yN.sub.1-y coating layer is characterized by a texture coefficient TC (1 1 1)>2.

A coated tool is, for example, a cutting tool which is provided with a base material and a coating layer located on the base material, wherein a cutting edge and a flank surface are located on the coating layer, the coating layer has a portion in which at least a titanium carbonitride layer and an aluminum oxide layer having an a-type crystal structure are laminated in this order, and, with regard to a texture coefficient (Tc) (hkl) which is calculated on a basis of a peak of the aluminum oxide layer analyzed by an X-ray diffraction analysis, a texture coefficient (Tc1) (146) as measured from a surface side of the aluminum oxide layer in the flank surface is 1 or more.

The present invention provides a diamond coated tool which is resistant to exfoliation at an interface between a base material and a diamond layer. The diamond coated tool of the present invention is a diamond coated tool including a base material and a diamond layer coating a surface of the base material, and characterized in that the surface of the base material has an arithmetic average roughness Ra of not less than 0.1 μm and not more than 10 μm and an average length of roughness profile elements RSm of not less than 1 μm and not more than 100 μm, and that the diamond layer has a plurality of cavities extending from a portion bordering on the base material in a crystal growth direction.

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.

The diamond coated tool of the present invention is a diamond coated tool including a base material and a diamond layer coating a surface of the base material, and characterized in that the surface of the base material has an arithmetic average roughness Ra of not less than 0.1 μm and not more than 10 μm and an average length of roughness profile elements RSm of not less than 3.1 μm and not more than 5.4 μm, and that the diamond layer has a plurality of cavities at a portion bordering on the base material.

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.

A composite diamond body includes a diamond base material and a stable layer disposed on the diamond base material. The stable layer may have a thickness of 0.001 μm or more and less than 10 μm, and may include a plurality of layers. A composite diamond tool includes the composite diamond body. There are thus provided highly wear-resistant composite diamond body and composite diamond tool that are even applicable to mirror-finish planarization of a workpiece which reacts with diamond to cause the diamond to wear.

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 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 containing a plurality of α-Al.sub.2O.sub.3 crystal grains. The α-Al.sub.2O.sub.3 layer includes a lower layer portion disposed at a side of the base material, an intermediate portion disposed on the lower layer portion, and an upper layer portion disposed on the intermediate portion. In a crystal orientation mapping performed on a polished cross-sectional surface of the α-Al.sub.2O.sub.3 layer using an EBSD, an area ratio of α-Al.sub.2O.sub.3 crystal grains with (001) orientation in the lower layer portion is less than 35%, an area ratio of α-Al.sub.2O.sub.3 crystal grains with (001) orientation in the intermediate portion is 35% or more, and an area ratio of α-Al.sub.2O.sub.3 crystal grains with (001) orientation in the upper layer portion is less than 35%.

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 containing a plurality of α-Al.sub.2O.sub.3 crystal grains. The α-Al.sub.2O.sub.3 layer includes: a first region made up of an edge ridgeline, a region A of a rake face, and a region B of a flank face; a second region which is a region of the rake face except for the region A and covered with the coating; and a third region which is a region of the flank face except for the region B. The α-Al.sub.2O.sub.3 layer satisfies a relation b−a>0.5, where a is an average value of a TC(006) in the first region in texture coefficient TC(hkl) and b is an average value of the TC(006) in the second region or the third region in texture coefficient TC(hkl).