Surface-coated cermet cutting tool with hard coating layer having excellent chipping resistance

Abstract

There is provided a surface-coated cermet cutting tool with a hard-coating layer having excellent chipping resistance. The surface-coated cermet cutting tool is formed by coating, on a surface of a tool substrate made of WC-based cemented carbide or TiCN-based cermet, a hard-coating layer including the following upper and lower layers (a) and (b): (a) as the lower layer, a Ti compound layer having at least one or two of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer and a TiCNO layer, all of which are deposited by chemical vapor deposition, the titanium compound layer having a total average thickness of 3 to 20 μm, and (b) as the upper layer, a heat-transformed α-type Al oxide layer formed by carrying out a heat-transforming treatment in a state that titanium oxide particulates satisfying the composition formula: TiO, (where value Y is 1.2 to 1.9 in an atomic ratio to Ti when measured by Auger Electron Spectroscopy) and chemically deposited as a transformation starting material are dispersedly distributed on a surface of an Al oxide layer having a κ-type or θ-type crystal structure deposited by chemical vapor deposition and satisfying the composition formula: (AlZr)O(where value X is 0.003 to 0.05 in an atomic ratio when measured by an electron probe micro-analyzer (EPMA)) to thereby transform the crystal structure of the Al oxide layer having the κ-type or θ-type crystal structure into an α-type crystal structure, the heat-transformed α-type Al oxide layer having an average thickness of 1 to 15 μm.