# US 9,752,230 B2 · Alpha alumina thin film for processing difficult-to-cut material and cast iron

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- Number: US 9,752,230 B2
- Document ID: US9752230B2
- Status: Granted
- Kind: B2
- Application number: 15/038,474
- Filed: 2014-11-26
- Published: 2016-10-13
- Granted: 2017-09-05
- Earliest claimed: 2013-12-23
- Assignees: Korloy Inc.
- Applicants: Korloy Inc.
- Inventors: Jae Hoon Kang; Dong Youl Lee; Jung Wook Kim; Han Sung Kim; Sung Gu Lee; Jin Woo Ahn; Sun Yong Ahn
- Web page: https://patentgrep.com/patent/US9752230B2

## CPC

- C23C 16/06: characterised by the deposition of metallic material
- C09D 1/00: Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
- C23C 16/44: characterised by the method of coating (C23C16/04 takes precedence)
- C23C 28/044: {coatings specially adapted for cutting tools or wear applications}
- C23C 28/048: {with layers graded in composition or physical properties}
- 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)
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)

## Abstract

Disclosed is an alpha alumina (α-Al2O3) thin film comprising the lower layer formed on the base material made from cemented carbide; and the α-Al2O3 thin film layer formed on the lower layer, wherein when the α-Al2O3 thin film layer is divided, from the total thickness (T) thereof, into a D1 layer which is from an interface layer to 0.15T, a D2 layer which is from 0.15T to 0.4T, and a D3 layer which is from 0.4T to 1T, an S1 (D3 layer grain size/D1 layer grain size) is 2-5.5 and an S2 (D2 layer grain size/D1 layer grain size) is 1.5-4.

## Claims

### Claim 1

An alpha alumina (α-Al2O3) thin film which has a thickness of T and is formed on a lower layer which is formed on a base material, the α-Al2O3 thin film being divided into:
a D1 layer which is positioned between an interfacial layer and 0.15T above the interfacial layer;
a D2 layer which is positioned between 0.15T and 0.4T above the interfacial layer; and
a D3 layer which is positioned between 0.4T and 1T above the interfacial layer,
wherein S1 (the grain size of the D3 layer/the grain size of the D1 layer) is 2 to 5.5, and S2 (the grain size of the D2 layer/the grain size of the D1 layer) is 1.5 to 4,
wherein the lower layer comprises:
a TiN layer formed on the base material;
a MT-TiCN layer formed on the TiN layer; and
an interfacial layer containing Ti and formed on the TiCN layer, and
wherein the interfacial layer comprises:
a TixAl1-xCNO layer formed on the MT-TiCN layer;
a AlyTi1-yCNO layer formed on the TixAl1-xCNO layer; and
a Ti oxide layer formed on the AlyTi1-yCNO layer.

### Claim 2 (depends on 1)

The α-Al2O3 thin film of claim 1, wherein the base material is a cemented carbide containing 5 to 10 wt % of Co, and at most 1 wt % of (Ta,Nb)C.

### Claim 3 (depends on 1)

The α-Al2O3 thin film of claim 1, wherein:
the thickness of the TiN layer is 0.1 to 2 μm;
the thickness of the MT-TiCN layer is 3 to 10 μm;
the thickness of the interfacial layer is 0.1 to 1 μm; and
the thickness of the α-Al2O3 layer is 2 to 8 μm.

### Claim 4 (depends on 1)

The α-Al2O3 thin film of claim 1, wherein:
the grain size of the D1 layer is 0.1 to 0.5 μm;
the grain size of the D2 layer is 0.15 to 0.8 μm; and
the grain size of the D3 layer is 0.4 to 1.5 μm.

### Claim 5 (depends on 1)

The α-Al2O3 thin film of claim 1, wherein the surface roughness (Ra) of the α-Al2O3 thin film is at most 250 nm.