Patent ID: 7422806
Filing Date: 2008-09-09
Classification: C23C,Y10T

Abstract:
1. A surface-coated cermet cutting tool with a hard coating layer for a high-speed intermittent cutting work, comprising: a tool substrate made of tungsten-carbide cemented carbide or titanium-carbonitride-cermet, the substrate being coated with the hard-coating layer including lower and upper layers: the lower layer comprising titanium compound layers having at least any two layers selected from the group consisting of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium carbooxide layer, and a titanium oxycarbonitride layer, the titanium compound layer having a total average layer thickness of 3 to 20 μm, and the upper layer comprising an aluminum oxide layer having an average layer thickness of 1 to 15 μm, wherein one layer of the titanium compound layers as the lower layer comprises a titanium carbonitride layer which has an average layer thickness of 2.5 to 15 μm and has the highest peak in Σ3 and a distribution ratio of the Σ3 to ΣN+1 ranges 60% to 80% in an atom sharing lattice point distribution graph showing the distribution ratio at which individual ΣN+1 occupy the total ΣN+1 (where the upper limit of N is 28 in relation to frequency) when a type of an atom sharing lattice point in which N lattice points (where N is an even number equal to or greater than 2 in an NaCl type face-centered cubic crystal structure) not sharing a constituent atom between the atom sharing lattice points exist is denoted by ΣN+1, the atom sharing lattice point distribution graph being obtained by using a field-emission scanning electron microscope to irradiate electron beams to individual crystal particles existing in a measuring range of a surface-polished plane and to measure a tilt angle formed by the normal lines of (001) plane and (011) plane as a crystal plane of the crystal particles, the crystal particles having an NaCl type face-centered cubic crystal structure in which constituent atoms including titanium, carbon, and nitrogen exist in the lattice points, calculating a distribution of lattice points (atom sharing lattice points) in which each constituent atom is shared with the crystal particles in an interface between adjacent crystal particles on the basis of the measured tilt angles.