| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface coated cermet cutting tool having a hard coated layer exhibiting superior heat and impact resistance. SOLUTION: This cutting tool is so formed that (a) a lower layer by chemical vapor deposition, (b) an upper layer, (c) a surface layer and (d) the hard coated layer are formed on the surface of a tool base body comprising WC-group cemented carbide or TiCN-group cermet. The lower layer comprises a single layer or more layers of Ti compound layer having the mean total layer thickness of 0.5-20μm. The upper layer comprises a composite doubleαtype Al<SB>2</SB>O<SB>3</SB>layer constituted of a lower side layer, which has a structure having a constant crystal structure under a state formed by the chemical vapor deposition and dispersedly distributed with transformation cracks, and a heat transformationαtype Al<SB>2</SB>O<SB>3</SB>layer with the mean layer thickness of 1-20μm; and an upper side layer of a vapor depositionαtype Al<SB>2</SB>O<SB>3</SB>layer having the means layer thickness of 0.1-2μm. The hard coated layer comprises the surface layer of Ti oxide layer formed by vapor deposition, satisfying a specific composition formula: TiO<SB>x</SB>and having the mean layer thickness of 0.1-3μm; and an uppermost color identification layer comprising TiN layer having the mean layer thickness of 0.05-2μm. COPYRIGHT: (C)2005,JPO&NCIPI
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