| 摘要 |
A surface-coated cermet cutting tool with a hard coating layer having excellent chipping resistance in a high-speed intermittent cutting work is provided. The surface-coated cermet cutting tool is formed by coating, on a surface of a tool substrate made of tungsten-carbide-based cemented carbide or titanium-carbonitride-based cermet, the hard-coating layer including the following upper and lower layers (a) and (b): (a) as the lower layer, a titanium compound layer having at least two layers of a titanium carbide layer, a titanium nitride layer, a titanium carbonitride layer, a titanium carbooxide layer, and a titanium oxycarbonitride layer, all of which are deposited by chemical vapor deposition, the titanium compound layer having a total average layer thickness of 3 to 20 µm, and (b) as the upper layer, an aluminum oxide layer having an average layer thickness of 1 to 15 µm, which is deposited by chemical vapor deposition. Here, one layer of the titanium compound layer as the lower layer (a) comprises a titanium carbonitride layer which has an average layer thickness of 2.5 to 15 µm and which indicates an atom sharing lattice point distribution graph in which the highest peak exists in £3 and a distribution ratio of the £3 to £N+1 ranges 60% to 80% in the atom sharing lattice point distribution graph showing the distribution ratio at which individual £N+1 occupy the total £N+1 (where the upper limit 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 in the atom sharing lattice points exist is denoted by £N+1. The atom sharing lattice point distribution graph is 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. |
