SURFACE-COATED CUTTING TOOL EXHIBITING EXCELLENT CHIPPING RESISTANCE IN HARD COATING LAYER

摘要

PROBLEM TO BE SOLVED: To provide a surface-coated cutting tool which exhibits excellent chipping resistance and loss resistance in a hard coating layer in high-speed intermittent cutting processing.SOLUTION: The hard coating layer is composed of a lower layer and an upper layer which are chemically vapor-deposited. (a) The lower layer is a Ti-compound layer containing at least one layer of a Ti-carbonitride layer and composed of one layer or two or more layers having a total average layer thickness of 3 to 20 μm. (b) The upper layer is an aluminum oxide layer containing an average layer thickness of 2 to 25 μm. The aluminum oxide layer constituting the upper layer has a columnar longitudinally-grown aluminum oxide crystal organization, and a fine-particle aluminum oxide taking a bimodal particle diameter distribution form exists in the organization.