# US 2021/0340662 A1 · Low friction wear film and method for producing the same

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- Number: US 2021/0340662 A1
- Document ID: US20210340662A1
- Status: Published application
- Kind: A1
- Application number: 17/240,075
- Filed: 2021-04-26
- Published: 2021-11-04
- Earliest claimed: 2020-04-30
- Assignees: Aisin Corporation; Tohken Thermo Tech Co., Ltd
- Applicants: Aisin Corporation; Tohken Thermo Tech Co., Ltd
- Inventors: Chengji JIN; Hodo SUZUKI; Masaki KAJINO; Kazuya KITAMURA; Naoyuki OMORI
- Web page: https://patentgrep.com/patent/US20210340662A1

## CPC

- C23C 14/025: {Metallic sublayers}
- C23C 16/26: Deposition of carbon only
- C23C 14/0084: {Producing gradient compositions}
- C23C 14/027: {Graded interfaces}
- C23C 14/0605: {Carbon}
- C23C 14/0635: {Carbides}
- C23C 14/165: {by cathodic sputtering}
- C23C 14/34: Sputtering
- C23C 14/352: {using more than one target (C23C14/56 takes precedence)}
- C23C 28/322: {only coatings of metal elements only}
- C23C 28/325: {with layers graded in composition or in physical properties}
- C23C 28/341: {with at least one carbide layer}
- C23C 28/36: {including 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)

## Abstract

A low friction wear film includes a chromium layer provided on a surface of a metal substrate, a tungsten carbide layer provided on a surface of the chromium layer, and a diamond-like carbon layer as a top layer provided on a surface of the tungsten carbide layer. The tungsten carbide layer includes a chromium-tungsten carbide gradient layer and a tungsten carbide uniform layer. In the tungsten carbide layer, a tungsten-concentrated layer in which a tungsten simple substance is present is not provided at a boundary between the chromium-tungsten carbide gradient layer and the tungsten carbide uniform layer.

## Claims

### Claim 1

A low friction wear film comprising:
a chromium layer provided on a surface of a metal substrate;
a tungsten carbide layer provided on a surface of the chromium layer, the tungsten carbide layer including a chromium-tungsten carbide gradient layer and a tungsten carbide uniform layer, the chromium-tungsten carbide gradient layer containing chromium and tungsten carbide and having a gradient composition in which a composition ratio of the chromium decreases and a composition ratio of the tungsten carbide increases as a distance from the chromium layer in a thickness direction increases, the tungsten carbide uniform layer being made of tungsten carbide provided on a surface of the chromium-tungsten carbide gradient layer, and in the tungsten carbide layer, a tungsten-concentrated layer in which a tungsten simple substance is present is not provided at a boundary between the chromium-tungsten carbide gradient layer and the tungsten carbide uniform layer; and
a diamond-like carbon layer as a top layer provided on a surface of the tungsten carbide layer.

### Claim 2 (depends on 1)

The low friction wear film according to claim 1, wherein a ratio of an atomic concentration of tungsten to a total of the atomic concentration of the tungsten and an atomic concentration of carbon in the tungsten carbide layer is 50% or less.

### Claim 3

A method for producing a low friction wear film, the low friction wear film including: a chromium layer that is provided on a surface of a metal substrate; a tungsten carbide layer that is provided on a surface of the chromium layer, the tungsten carbide layer including a chromium-tungsten carbide gradient layer and a tungsten carbide uniform layer, the chromium-tungsten carbide gradient layer containing chromium and tungsten carbide and having a gradient composition in which a composition ratio of the chromium decreases and a composition ratio of the tungsten carbide increases as a distance from the chromium layer in a thickness direction increases, the tungsten carbide uniform layer being made of tungsten carbide provided on a surface of the chromium-tungsten carbide gradient layer; and a diamond-like carbon layer as a top layer that provided on a surface of the tungsten carbide layer, the method comprising:
as a chromium layer deposition step, depositing the chromium layer by causing inert gas ions to collide with a chromium target made of chromium placed in a vacuum chamber to cause chromium atoms sputtered from the chromium target to adhere to the surface of the metal substrate;
as a chromium-tungsten carbide gradient layer deposition step, depositing the chromium-tungsten carbide gradient layer by causing inert gas ions to collide with the chromium target and a tungsten carbide target made of tungsten carbide placed in the vacuum chamber to cause chromium atoms sputtered from the chromium target and tungsten carbide component sputtered from the tungsten carbide target to adhere to the surface of the chromium layer;
as a tungsten carbide uniform layer deposition step, depositing the tungsten carbide uniform layer by causing inert gas ions to collide with the tungsten carbide target placed in the vacuum chamber to cause the tungsten carbide component sputtered from the tungsten carbide target to adhere to the surface of the chromium-tungsten carbide gradient layer;
as a hydrocarbon ionization step, introducing a hydrocarbon gas into the vacuum chamber and ionizing the introduced hydrocarbon gas; and
depositing the diamond-like carbon layer by causing hydrocarbon ionized in the hydrocarbon ionization step to adhere to the surface of the tungsten carbide uniform layer,
wherein the hydrocarbon ionization step is started before the tungsten carbide uniform layer deposition step is carried out.

### Claim 4 (depends on 3)

The method according to claim 3, wherein the hydrocarbon ionization step is started at the same time as start of the chromium-tungsten carbide gradient layer deposition step.