Piston ring and its production method

Patent metadata

Field	Value
Publication number	US-10006547-B2
Application number	US-201415033308-A
Country	US
Kind code	B2
Filing date	Oct 27, 2014
Priority date	Oct 31, 2013
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

To provide a hard-amorphous-carbon-coated piston ring having low friction and excellent wear resistance and peeling resistance to reduce the fuel consumption of automobiles, an outer peripheral surface of a steel-made piston ring base material is provided with a primary layer constituted by a CrN/Cr laminate coating or a CrN/TiN laminate coating as thick as 10-60 μm, which is obtained by alternately laminating CrN-type chromium nitride and chromium metal or TiN-type titanium nitride, an intermediate layer of chromium metal and/or titanium metal as thick as 0.05-1.0 μm, and then a hard amorphous carbon coating as thick as 0.4-20 μm.

First claim

What is claimed is:

1. A piston ring having a hard amorphous carbon coating at least on its outer peripheral sliding surface, the piston ring comprising:
a base material of said piston ring comprising steel;
a primary layer on the base material; and
an intermediate layer on the primary layer; and
said hard amorphous carbon coating having a thickness of 0.4-20 μm on the intermediate layer, wherein
the intermediate layer is interposed between said primary layer and said hard amorphous carbon coating,
said primary layer comprises a CrN/Cr or CrN/TiN laminate coating and have a thickness of 10-60 μm, which is an alternate laminate of chromium nitride mainly composed of CrN and chromium metal or titanium nitride mainly composed of TiN,
said intermediate layer comprises chromium metal and/or titanium metal and has a thickness of 0.05-1.0 μm, and
an interface of the primary layer with said intermediate layer has a composite structure comprising said chromium nitride and said chromium metal, or a composite structure comprising said chromium nitride and said titanium nitride.

2. The piston ring according to claim 1 , wherein in said CrN/Cr laminate coating, a CrN/Cr laminate unit composed of a CrN layer and a Cr layer is as thick as 30-120 nm, in a range of 1-3 times the sum of the crystallite size of said chromium nitride and the crystallite size of said metal chromium.

3. The piston ring according to claim 1 , wherein in said CrN/TiN laminate coating, a CrN/TiN laminate unit composed of a CrN layer and a TiN layer is as thick as 20-100 nm, in a range of 1-3 times the sum of the crystallite size of said chromium nitride and the crystallite size of said titanium nitride.

4. The piston ring according to claim 1 , wherein carbon (C) is dissolved in said chromium nitride.

5. The piston ring according to claim 1 , wherein the base material of the piston ring has a surface roughness Rz JIS of 0.05-3 μm, and said composite structure has a contour line pattern.

6. The piston ring according to claim 1 , wherein said hard amorphous carbon coating has a hydrogen content of 5 atomic % or less.

7. A method for producing a piston ring having a hard amorphous carbon coating at least on its outer peripheral sliding surface, comprising the steps of:
adjusting the surface roughness Rz JIS of a base material of said piston ring comprising steel to 0.05-3 μm;
alternately laminating chromium nitride mainly composed of CrN and chromium metal or titanium nitride mainly composed of TiN to form a CrN/Cr laminate coating or a CrN/TiN laminate coating having a thickness of 15-70 μm on the base material;
grinding said CrN/Cr laminate coating or said CrN/TiN laminate coating; and
forming an intermediate metal layer on the laminate coating and the hard amorphous carbon coating having a thickness of 0.4-20 μm on the intermediate metal layer.

Assignees

• Kk Riken

Inventors

• Sato Masayuki
• Murayama Yuuichi
• IWAMOTO Youhei
• Sekiya Takuma

Classifications

• C23C14/0641

  Nitrides (C23C14/0617 takes precedence) · CPC title

• C23C28/042

  including a refractory ceramic layer, e.g. refractory metal oxides, ZrO2, rare earth oxides · CPC title

• C23C28/34

  including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates · CPC title

• C23C14/16

  on metallic substrates or on substrates of boron or silicon · CPC title

• C23C28/343

  with at least one DLC or an amorphous carbon based layer, the layer being doped or not · CPC title