Piston ring and its production method

Patent metadata

Field	Value
Publication number	US-2016238133-A1
Application number	US-201415033308-A
Country	US
Kind code	A1
Filing date	Oct 27, 2014
Priority date	Oct 31, 2013
Publication date	Aug 18, 2016
Grant date	—

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

1 . A piston ring having a hard amorphous carbon coating having a thickness of 0.4-20 μm at least on its outer peripheral sliding surface;
the base material of said piston ring being steel;
a primary layer and an intermediate layer being interposed between said base material and said hard amorphous carbon coating;
said primary layer comprising a CrN/Cr or CrN/TiN laminate coating as thick as 10-60 μm, which is an alternate laminate of CrN-type chromium nitride and chromium metal or TiN-type titanium nitride; and
said intermediate layer comprising chromium metal and/or titanium metal as thick as 0.05-1.0μm.

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 CrN-type chromium nitride.

5 . The piston ring according to claim 1 , wherein 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.

6 . The piston ring according to claim 5 , wherein said composite structure has a contour-like pattern.

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

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

Assignees

• Kk Riken

Inventors

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

Classifications

• C23C28/343

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

• C23C28/42

  characterized by the composition of the alternating layers · CPC title

• C23C28/322

  only coatings of metal elements only · CPC title

• F16J9/26 Primary

  characterised by the use of particular materials · 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