SURFACE COATED CUTTING TOOL MADE OF CERMET HAVING PROPERTY-MODIFIED ALPHA TYPE Al2O3 LAYER OF HARD COATING LAYER HAVING EXCELLENT CRYSTAL GRAIN INTERFACE STRENGTH

摘要

PROBLEM TO BE SOLVED: To provide a surface coated cermet cutting tool, with property-modified α-type Al₂O₃ layer in a hard coating layer, having excellent crystal grain interface strength.;SOLUTION: The cutting tool of cermet comprises the hard coating layer comprising a lower layer of Ti compound layer and an upper layer of an α-type Al₂O₃ layer, formed on the surface of a tool base member. A field emission type scanning electron microscope and an electron back-scattered diffraction image device are used to radiate an electronic beam to each crystal grain having a hexagonal crystal grid existing in a measurement range of a surface polished face, so that the angle of the normal line of each crystal face of the crystal grain to the normal line of the surface-polished face where they cross each other is measured. Based on the result of this measurement, faces (0001) and faces {10-10} are selected, and among the selected faces (0001) and faces {10-10}, the angle of the normal lines of the faces (0001) in the interface (by the unit of crystal grain interface) between adjoining crystal grains to each other and to the normal lines of faces {10-10} where they cross each other is 15 deg. or less in crystal grain interface units in 45% or more of total crystal grain interface units in the reformed α-type Al₂O₃ layer to compose the device.;COPYRIGHT: (C)2007,JPO&INPIT