CUTTING TOOL MADE OF SURFACE COATED CUBIC BORON NITRIDE SINTERED MATERIAL WITH HARD COATING LAYER EXERTING EXCELLENT CHIPPING RESISTANCE AND THERMOPLASTIC DEFORMATION RESISTANCE IN HIGH-SPEED INTERMITTENT CUTTING OF HIGH HARDNESS STEEL

摘要

PROBLEM TO BE SOLVED: To provide a cutting tool made of a surface coated cubic boron nitride sintered material with a hard coating layer exerting excellent chipping resistance and thermoplastic deformation resistance in high-speed intermittent cutting of high hardness steel.;SOLUTION: The cutting tool is constituted by forming the hard coating layer composed of the following upper and lower layers (a) and (b) on the surface of a tool body comprising a cubic boron nitride sintered material: (a) as the lower layer, a compound nitride layer of Ti, Al, and Si having an average layer thickness of 0.5-10 μm and satisfying a composition formula : [Ti_1-(X+Z)Al_XSi_Z]N (wherein X shows 0.40 to 0.60 and Z shows 0.01 to 0.10 by atomic ratio), and (b) as the upper layer, a heat-transformed α-type Al₂O₃ layer formed by transforming a crystal structure of an Al₂O₃ layer having a κ-type or θ-type crystal structure into an α-type crystal structure by executing heat treatment on the surface of the Al₂O₃ layer, which has the κ-type or θ-type crystal structure and an average layer thickness of 0.5-10 μm in a state of being formed by vapor deposition, after a titanium oxide layer having an average layer thickness of 0.05-1 μm is formed on the surface of the Al₂O₃ layer by vapor deposition.;COPYRIGHT: (C)2006,JPO&NCIPI