# US 11,998,993 B2 · Cutting tool

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- Number: US 11,998,993 B2
- Document ID: US11998993B2
- Status: Granted
- Kind: B2
- Application number: 17/298,966
- Filed: 2019-12-12
- Published: 2022-02-03
- Granted: 2024-06-04
- Earliest claimed: 2019-02-19
- Assignees: Sumitomo Electric Hardmetal Corp.
- Applicants: Sumitomo Electric Hardmetal Corp.
- Inventors: Susumu Okuno; Shinya Imamura; Yuki Rikiso; Yasuki Kido; Fumiyoshi Kobayashi
- Web page: https://patentgrep.com/patent/US11998993B2

## CPC

- B23B 27/148: {Composition of the cutting inserts}
- C23C 30/005: {on hard metal substrates}
- B23B 27/14: Cutting tools of which the bits or tips {or cutting inserts} are of special material
- B23B 51/00: Tools for drilling machines
- B23C 5/16: characterised by physical features other than shape
- C23C 14/06: characterised by the coating material ({C23C14/0021} , C23C14/04 take precedence)
- C23C 14/08: Oxides (C23C14/10 takes precedence)
- C23C 16/34: Nitrides {(C23C16/303 takes precedence)}
- C23C 16/36: Carbonitrides
- C23C 16/40: Oxides
- C23C 16/403: {of aluminium, magnesium or beryllium}
- C23C 28/04: only coatings of inorganic non-metallic material
- C23C 28/044: {coatings specially adapted for cutting tools or wear applications}
- B23B 2224/04: Aluminium oxide
- B23B 2224/32: Titanium carbide nitride (TiCN)
- B23B 2224/36: Titanium nitride
- 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)
- B23C: MILLING (broaching B23D; broach-milling in making gears B23F; arrangement for copying or controlling B23Q)

## Abstract

A cutting tool comprises a substrate and a coating that coats the substrate, the coating including an α-alumina layer provided on the substrate, the α-alumina layer including crystal grains of α-alumina, the α-alumina layer including a lower portion and an upper portion, the upper portion being occupied in area at a ratio of 50% or more by crystal grains of α-alumina having a (006) plane with a normal thereto having a direction within ±15° with respect to a direction of the normal to the second interface, the lower portion being occupied in area at a ratio of 50% or more by crystal grains of α-alumina having a (110) plane with a normal thereto having a direction within ±15° with respect to the direction of the normal to the second interface, the α-alumina layer having a thickness of 3 μm or more and 20 μm or less.

## Claims

### Claim 1

A cutting tool comprising a substrate and a coating that coats the substrate,
the coating including an α-alumina layer provided on the substrate, the α-alumina layer including crystal grains of α-alumina,
the α-alumina layer including a lower portion and an upper portion,
the lower portion being a region sandwiched between an imaginary plane A and an imaginary plane B, the imaginary plane A being an imaginary plane which passes through a point 0.2 μm away in a direction of thickness from a first interface located on a side of the substrate and is parallel to the first interface, the imaginary plane B being an imaginary plane which passes through a point 1.3 μm further away from the imaginary plane A in the direction of thickness and is parallel to the first interface,
the upper portion being a region sandwiched between an imaginary plane C and an imaginary plane D, the imaginary plane C being an imaginary plane which passes through a point 0.5 μm away in the direction of thickness from a second interface opposite to the side of the substrate and is parallel to the second interface, the imaginary plane D being an imaginary plane which passes through a point 1 μm further away from the imaginary plane C in the direction of thickness and is parallel to the second interface,
the first interface being parallel to the second interface,
when a cross section of the α-alumina layer obtained when cut along a plane including a normal to the second interface is subjected to an electron backscattering diffraction image analysis using a field emission scanning microscope to determine a crystal orientation of each of the crystal grains of α-alumina and a color map is created based thereon,
then, in the color map,
the upper portion being occupied in area at a ratio of 50% or more by crystal grains of α-alumina having a (006) plane with a normal thereto having a direction within ±15° with respect to a direction of the normal to the second interface,
the lower portion being occupied in area at a ratio of 50% or more by crystal grains of α-alumina having a (110) plane with a normal thereto having a direction within ±15° with respect to the direction of the normal to the second interface,
the α-alumina layer having a thickness of 3 μm or more and 20 μm or less.

### Claim 2 (depends on 1)

The cutting tool according to claim 1, wherein
the coating further includes an inner layer provided between the substrate and the α-alumina layer, and
the inner layer includes TiCN.

### Claim 3 (depends on 2)

The cutting tool according to claim 2, wherein
the coating further includes an intermediate layer provided between the inner layer and the α-alumina layer,
the intermediate layer includes a compound composed of: elemental titanium; and at least one element selected from the group consisting of carbon, nitrogen, boron and oxygen, and
the intermediate layer is different in composition from the inner layer.

### Claim 4 (depends on 1)

The cutting tool according to claim 1, wherein
the coating further includes an outermost layer provided on the α-alumina layer, and
the outermost layer includes a compound composed of: an elemental titanium; and one element selected from the group consisting of carbon, nitrogen, and boron.

### Claim 5 (depends on 1)

The cutting tool according to claim 1, wherein the coating has a thickness of 3 μm or more and 30 μm or less.

### Claim 6 (depends on 1)

The cutting tool according to claim 1, wherein
in the color map, the upper portion is occupied in area at a ratio of 50% or more and 90% or less by crystal grains of α-alumina having a (006) plane with a normal thereto having a direction within ±15° with respect to a direction of the normal to the second interface.

### Claim 7 (depends on 1)

The cutting tool according to claim 1, wherein
in the color map, the lower portion is occupied in area at a ratio of 50% or more and 90% or less by crystal grains of α-alumina having a (110) plane with a normal thereto having a direction within ±15° with respect to a direction of the normal to the second interface.

### Claim 8 (depends on 2)

The cutting tool according to claim 2, wherein
the inner layer has a thickness of 3 μm or more and 20 μm or less.

### Claim 9 (depends on 3)

The cutting tool according to claim 3, wherein
the intermediate layer includes TiCNO, TiBN, or TiB2.

### Claim 10 (depends on 3)

The cutting tool according to claim 3, wherein
the intermediate layer has a thickness of 0.3 μm or more and 2.5 μm or less.

### Claim 11 (depends on 4)

The cutting tool according to claim 4, wherein
the outermost layer includes TiC, TiN, or TiB2.

### Claim 12 (depends on 4)

The cutting tool according to claim 4, wherein
the outermost layer has a thickness of 0.1 μm or more and 11 μm or less.