| abstract |
A coated hard metal which has high resistance against wear, chipping, welding,nand flaking is offered. The coated hard metal is provided with an inner layer,nintermediate layer, and outer layer on the surface of the hard metal. The innernlayer includes a layer comprising at least one member selected from the groupnconsisting of (a) the carbides, nitrides, borides, and oxides of the elements belongingnto the IVa, Va, and VIa groups in the periodic table and (b) the solidnsolutions of these. The intermediate layer includes a layer comprising at leastnone member selected from the group consisting of aluminum oxide, zirconiumnoxide, and their solid solution. The outer layer includes a layer of titanium carbonitridenhaving a columnar structure. In a cross section showing the structurenof the coated hard metal, the relation between " Amax ," which signifies thenmaximum roughness at the outer face of the intermediate layer, and "Bmax," nwhich signifies the maximum roughness at the outer face of the layer of titaniumncarbonitride having a columnar structure in the outer layer, satisfies equationn1.n ( Bmax / Amax ) < 1 n where 0.5 µm < Amax < 4.5 µm, and 0.5 µm ≦ Bmax ≦4.5 µm. |