| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface coated cermet cutting tool having thickenedαtype Al<SB>2</SB>O<SB>3</SB>layer exhibiting excellent chipping resistance. SOLUTION: The hard coating layer composed of the below-mentioned lower and upper layers (a) and (b) is formed on the surface of a tool base substance composed of WC-based cemented carbide or TiC-based cermet. The lower layer (a) is a Ti compound layer which is composed of one layer or two layers or more formed by chemical vapor deposition, and has total average layer thickness of 0.5 to 10μm as a lower layer, and the upper layer (b) is a thickened reformedαtype Al<SB>2</SB>O<SB>3</SB>layer which hasαtype crystal structure in a state formed by chemical vapor deposition, indicates a specific inclination angle frequency distribution graph, and has an average layer thickness of 16 to 30μm in the inclination angle frequency distribution graph where the inclination angle formed by a normal line of (001) surface which is a crystal surface of the crystal grains is measured by using a field emission type scanning electron microscope, the measured inclination angle within the range of 0 to 45 degrees among the measured inclination angle is divided for every 0.25 degree pitch, and the frequency existing in each division is totaled. COPYRIGHT: (C)2007,JPO&INPIT
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