# US 10,307,831 B2 · Surface coating cutting tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,307,831 B2 - Document ID: US10307831B2 - Status: Granted - Kind: B2 - Application number: 15/311,123 - Filed: 2015-05-14 - Published: 2017-03-30 - Granted: 2019-06-04 - Earliest claimed: 2014-05-16 - Assignees: Mitsubishi Materials Corporation - Applicants: Mitsubishi Materials Corporation - Inventors: Masaki Okude; Kenji Yamaguchi - Web page: https://patentgrep.com/patent/US10307831B2 ## CPC - B23B 27/148: {Composition of the cutting inserts} - B23B 27/14: Cutting tools of which the bits or tips {or cutting inserts} are of special material - C23C 16/30: Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides - C23C 28/042: {including a refractory ceramic layer, e.g. refractory metal oxides, ZrO2, rare earth oxides} - C23C 28/044: {coatings specially adapted for cutting tools or wear applications} - C23C 30/005: {on hard metal substrates} - B23B 2222/16: Cermet - B23B 2222/28: Details of hard metal, i.e. cemented carbide - B23B 2224/04: Aluminium oxide - B23B 2224/28: Titanium carbide - B23B 2224/32: Titanium carbide nitride (TiCN) - B23B 2224/36: Titanium nitride - B23B 2228/105: with specified thickness - B23B: TURNING; BORING (arrangements for copying or controlling B23Q) - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) ## Abstract A surface-coated cutting tool of the invention is a surface-coated cutting tool in which a surface of a tool body is coated with a lower layer and an upper layer, in which at least one layer of the lower layer is made of a TiCN layer, the upper layer has an average layer thickness of 2 to 15 μm and is made of an Al2O3 layer having an α-type crystal structure in a chemically deposited state, and in a coincidence grain boundary distribution graph, a highest peak is present in Σ3 in the range of Σ3 to Σ29, a distribution ratio of Σ3 occupies 35 to 70% of the whole coincidence grain boundary length of Σ3 or more, and a coincidence grain boundary of Σ31 or more occupies 25 to 60% of the whole coincidence grain boundary length of Σ3 or more. ## Claims ### Claim 1 A surface-coated cutting tool, comprising: a tool body that is made of a cemented carbide made from tungsten carbide or a titanium carbonitride cermet; and a hard coating layer that is deposited on a surface of the tool body, wherein the hard coating layer has a lower layer that is formed on the surface of the tool body and an upper layer that is formed on the lower layer, (a) the lower layer is made of a Ti compound layer, which has an average total layer thickness of 3 to 20 μm, and is composed of two or more of a TiC layer, a TiN layer, a TiCN layer, a TiCO layer, and a TiCNO layer, the Ti compound layer including at least one TiCN layer, (b) the upper layer is made of an Al2O3 layer, which has an average layer thickness of 1 to 30 μm and has an α-type crystal structure in a chemically deposited state, (c) regarding Al2O3 crystal grains of the upper layer, in a coincidence grain boundary distribution graph showing ratios of coincidence grain boundary lengths formed of respective constituent atom-sharing lattice points to the whole coincidence grain boundary length, a highest peak is present in Σ3 in the range of Σ3 to Σ29, and a distribution ratio of Σ3 occupies 35 to 70% of the whole coincidence grain boundary length of Σ3 or more, when electron beams are irradiated to the individual crystal grains in a measurement range of a polished cross-section by using a field-emission-type scanning electron microscope and an electron beam backward scattering diffraction device to measure angles of orientations of normal lines of crystal lattice planes having a corundum hexagonal crystal lattice, a crystal orientation relationship between the adjacent crystal lattices is calculated based on the measurement result, a distribution of a coincidence grain boundary formed of lattice points (constituent atom-sharing lattice points) where each of constituent atoms of a crystal lattice interface shares one constituent atom between the crystal lattices is calculated, and distribution ratios of individuals of ΣN+1 are calculated when ΣN+1 represents the constituent atom-sharing lattice point type in which there are N lattice points sharing no constituent atoms between the constituent atom-sharing lattice points, (d) regarding the Al2O3 crystal grains of the upper layer, in a coincidence grain boundary distribution graph showing ratios of coincidence grain boundary lengths formed of respective constituent atom-sharing lattice points to the whole coincidence grain boundary length, a total distribution ratio of the coincidence grain boundary of Σ31 or more occupies 25 to 60% of the whole coincidence grain boundary length of Σ3 or more, when electron beams are irradiated to the individual crystal grains in a measurement range of a polished cross-section by using a field-emission-type scanning electron microscope and an electron beam backward scattering diffraction device to measure angles of orientations of normal lines of crystal lattice planes having a corundum hexagonal crystal lattice, a crystal orientation relationship between the adjacent crystal lattices is calculated based on the measurement result, a distribution of a coincidence grain boundary formed of lattice points (constituent atom-sharing lattice points) where each of constituent atoms of a crystal lattice interface shares one constituent atom between the crystal lattices is calculated, and distribution ratios of individuals of ΣN+1 are calculated when ΣN+1 represents the constituent atom-sharing lattice point type in which there are N lattice points sharing no constituent atoms between the constituent atom-sharing lattice points, and an outermost surface layer of the lower layer is made of a TiCN layer having a layer thickness of at least 500 nm or more, except for oxygen as an inevitable impurity, oxygen is contained only in a depth region with a depth of up to 500 nm from an interface between the TiCN layer and the upper layer, and an average content of the oxygen contained in the depth region is 1 to 3 atom % of a total content of Ti, C, N, and O contained in the depth region. ### Claim 2 (depends on 1) The surface-coated cutting tool according to claim 1, wherein regarding the Al2O3 crystal grains of the upper layer, in a case where observation and elemental analysis based on high-angle scattering annular dark-field scanning transmission microscopy method is performed on the polished cross-section, sulfur is segregated to the coincidence grain boundary of Σ31 or more, and a grain boundary length of Σ31 or more in which the sulfur is segregated is 30% or greater of the whole coincidence grain boundary length of Σ31 or more.