Alloy member and method for hardening surface thereof

Patent metadata

Field	Value
Publication number	US-12320010-B2
Application number	US-202318097536-A
Country	US
Kind code	B2
Filing date	Jan 17, 2023
Priority date	Jan 3, 2017
Publication date	Jun 3, 2025
Grant date	Jun 3, 2025

Abstract

The present disclosure relates to a titanium or titanium alloy member and to a surface hardening method for the titanium or titanium alloy member. The titanium or titanium alloy member includes a base material of titanium or titanium alloy, and at a surface of the base material, a hardened layer formed by diffusion of oxygen into the surface.

First claim

The invention claimed is:

1. An alloy member comprising:
a base material of titanium or titanium alloy; and
at a surface of the base material, a hardened layer formed by diffusion of oxygen into the surface,
wherein the hardened layer includes (i) a surface transparent oxide layer, and (ii) a diffusion layer disposed internally from the surface transparent oxide layer.

2. The alloy member according to claim 1 , wherein the diffusion layer is thicker than the surface transparent oxide layer.

3. An alloy member comprising:
a base material of titanium or titanium alloy; and
at a surface of the base material, a hardened layer formed by diffusion of oxygen into the surface,
wherein:
the hardened layer includes, in order inwardly from the surface of the base material, a surface transparent oxide layer, an external diffusion layer, and an internal diffusion layer,
the external diffusion layer includes a portion having a hardness greater than or equal to 300 Hv, the portion being disposed internally from the surface transparent oxide layer, and
the internal diffusion layer includes a portion having a hardness less than 300 Hv.

4. The alloy member according to claim 3 , wherein:
a concentration of oxygen dissolved in solid solution in the external diffusion layer is higher than that in the internal diffusion layer, and
the concentration of oxygen dissolved in solid solution in the internal diffusion layer gradually decreases from outside towards inside.

5. The alloy member according to claim 3 , wherein:
concentrations of oxygen and nitrogen dissolved in solid solution in the external diffusion layer are higher than those in the internal diffusion layer, and
the concentrations of oxygen and nitrogen dissolved in solid solution in the internal diffusion layer gradually decrease from outside towards inside.

6. The alloy member according to claim 3 , wherein the surface transparent oxide layer is thinner than the external diffusion layer and the internal diffusion layer.

7. The alloy member according to claim 6 , wherein:
a concentration of oxygen dissolved in solid solution in the external diffusion layer is higher than that in the internal diffusion layer, and
the concentration of oxygen dissolved in solid solution in the internal diffusion layer gradually decreases from outside towards inside.

8. The alloy member according to claim 1 , wherein the titanium or titanium alloy member is applicable to a casing component of a wristwatch or a clock.

9. The alloy member according to claim 8 , wherein the casing component includes a bezel, a bezel center region, a back cover, or a band.

Assignees

• Casio Computer Co Ltd

Inventors

• Sato Junichi
• Kobayashi Kazuma
• Nagasawa Shouta
• Inoue Kenichi
• Liu Chinfu
• Liu Wuchien
• Lin Tienchai
• Kao Weipin

Classifications

• C22F1/183 Primary

  of titanium or alloys based thereon · CPC title

• C22F1/02

  in inert or controlled atmosphere or vacuum (adjusting the composition of the atmosphere C21D1/76) · CPC title

• C22C14/00

  Alloys based on titanium · CPC title

• C23C8/02

  Pretreatment of the material to be coated (C23C8/04 takes precedence) · CPC title

• C23C8/80

  After-treatment · CPC title