| 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 0.5-10μm and satisfying a composition formula : [Ti<SB>1-(X+Z)</SB>Al<SB>X</SB>Si<SB>Z</SB>]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-transformedα-type Al<SB>2</SB>O<SB>3</SB>layer formed by transforming a crystal structure of an Al<SB>2</SB>O<SB>3</SB>layer having aκ-type orθ-type crystal structure into anα-type crystal structure by executing heat treatment on the surface of the Al<SB>2</SB>O<SB>3</SB>layer, which has theκ-type orθ-type crystal structure and an average layer thickness of 0.5-10μm in a state of being formed by vapor deposition, after a titanium oxide layer having an average layer thickness of 0.05-1μm is formed on the surface of the Al<SB>2</SB>O<SB>3</SB>layer by vapor deposition. COPYRIGHT: (C)2006,JPO&NCIPI
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