SURFACE COATED CERMET CUTTING TOOL HAVING HARD COATING LAYER EXHIBITING EXCELLENT CHIPPING RESISTANCE IN CUTTING DIFFICULT-TO-CUT MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a surface coated cermet cutting tool having a hard coating layer exhibiting excellent chipping resistance in cutting difficult-to-cut material.;SOLUTION: This cutting tool is a surface coated cermet tool formed by depositing the hard coating layer including: a lower layer formed of a Ti compound layer with an average layer thickness ranging from 3 to 20 μm; and an upper layer formed of a reformed α-type Al₂O₃ layer with an average layer thickness ranging from 6 to 20 μm on the surface of a tool base. In the tool, as a reinforcement layer, an α-type Al₂O₃ layer is interposed between the lower layer and the upper layer of the tool. In the case of measuring an angle of inclination made by a normal of (0001) face, which is a crystal plane of a crystal grain, using a field emission type scanning electron microscope to create an inclination angle frequency distribution graph, the α-type Al₂O₃ layer shows an inclination angle frequency distribution graph in which the highest peak exists in an inclination angle section within the range of 75 to 90 degrees, and the total of frequencies existing in the range of 75 to 90 degrees occupies 50% or more of the whole frequency, and has an average layer thickness ranging from 0.1 to 1.9 μm. Further, the surface roughness of the reformed α-type Al₂O₃ layer is set to Ra: 0.2 μm or less.;COPYRIGHT: (C)2007,JPO&INPIT