Piston ring

Patent metadata

Field	Value
Publication number	US-2016245407-A1
Application number	US-201415025756-A
Country	US
Kind code	A1
Filing date	Sep 1, 2014
Priority date	Sep 30, 2013
Publication date	Aug 25, 2016
Grant date	—

Abstract

The present invention provides a piston ring having excellent abrasion resistance to an aluminum alloy cylinder or cylinder liner formed of a mating material and is therefore capable of decreasing abrasion of the mating material. An exemplary piston ring has a hard carbon coating formed on an outer peripheral surface, and the hard carbon coating contains 0.5 atom % or more to less than 5 atom % of tungsten (W).

First claim

What is claimed is:

1 . A piston ring comprising a hard carbon coating formed on an outer peripheral surface, wherein the hard carbon coating contains 0.5 atom % or more to less than 5 atom % of tungsten (W).

2 . The piston ring according to claim 1 , wherein a friction coefficient of the hard carbon coating is 0.10 or less.

3 . The piston ring according to claim 1 , wherein the tungsten (W) contained in the hard carbon coating is in both forms of a carbide and a metal.

4 . The piston ring according to claim 1 , wherein the hard carbon coating contains 10 to 40 atom % of hydrogen.

5 . The piston ring according to claim 1 , wherein a thickness of the hard carbon coating is 0.5 to 20 μm.

6 . The piston ring according to claim 1 , wherein a Martens' hardness of the hard carbon coating is 5.5 to 15 GPa.

7 . The piston ring according to claim 1 , wherein a coupling ratio of an sp2 bond:sp3 bond in a carbon crystal structure of the hard carbon coating equals to 4:6 to 8:2.

8 . A piston ring comprising a hard carbon coating formed on at least one of two side surfaces, wherein the hard carbon coating contains 0.5 atom % or more to less than 5 atom % of tungsten (W).

9 . The piston ring according to claim 8 , wherein a Martens' hardness of the hard carbon coating is 3.5 to 10 GPa.

10 . The piston ring according to claim 8 , wherein the hard carbon coating is also formed on an outer peripheral surface of the piston ring and a ratio (M1/M2) of a Martens' hardness of the hard carbon coating formed on the at least one side surface (M1) and a Martens' hardness of the hard carbon coating formed on the outer peripheral surface (M2), is 0.3 to 0.8.

11 . The piston ring according to claim 10 , wherein a coupling ratio of an sp2 bond:sp3 bond in a carbon crystal structure of the hard carbon coating formed at the outer peripheral surface equals to 4:6 to 8:2, and wherein a coupling ratio of an sp2 bond:sp3 bond in a carbon crystal structure of the hard carbon coating formed on the side surface equals to 5:5 to 9:1.

12 . The piston ring according to claim 8 , wherein a friction coefficient of the hard carbon coating is 0.10 or less.

13 . The piston ring according to claim 8 , wherein the tungsten (W) contained in the hard carbon coating is in both forms of a carbide and a metal.

14 . The piston ring according to claim 8 , wherein the hard carbon coating contains 10 to 40 atom % of hydrogen.

15 . The piston ring according to claim 8 , wherein a thickness of the hard carbon coating is 0.5 to 20 μm.

Assignees

• Kk Riken

Inventors

• Honda Keiji
• Tsuji Katsuhiro
• Moronuki Masaki
• Sekiya Takuma

Classifications

• C23C14/0605

  Carbon · CPC title

• C23C14/024

  Deposition of sublayers, e.g. to promote adhesion of the coating (C23C14/027 takes precedence) · CPC title

• F02F5/00

  Piston rings, e.g. associated with piston crown · CPC title

• F16J10/04

  Running faces; Liners · CPC title

• C23C14/0635

  Carbides · CPC title