Piston ring
AssigneeRiken
InventorsMasayuki Sato, Yuuichi Murayama, Youhei Iwamoto, Takuma Sekiya
Life of this patent
Estimating the term…
Abstract
To provide a piston ring having a hard laminate coating having excellent scuffing resistance, wear resistance and peeling resistance, which can be used in an environment of high mechanical and thermal load in engines, the piston ring is provided on its outer peripheral sliding surface with a CrN-type hard coating as thick as 10-60 μm and comprising a CrN/CrCN laminate coating having hardness Hv of 1000 or more and residual compression stress of 1500 MPa or less, a laminate unit composed of a CrN layer and a CrCN layer being as thick as 30 nm or more; the CrN/CrCN laminate coating being formed by alternately laminating CrN layers and CrCN layers containing C dissolved in CrN by ion plating.
Claims8
A piston ring having a CrN-type hard coating as thick as 10-60 μm formed on its outer peripheral sliding surface;
- said CrN-type hard coating comprising a CrN/CrCN laminate coating obtained by alternately laminating CrN layers and CrCN layers containing C dissolved in CrN;
- a laminate unit composed of said CrN layer and said CrCN layer being as thick as 30-100 nm;
- and
- said CrN-type hard coating having hardness Hv of 1000-1450, and residual compression stress of 1500 MPa or less;
- wherein an outermost surface of said outer peripheral sliding surface has a composite structure comprising a CrN phase and a CrCN phase containing C dissolved in CrN.
A method for producing a piston ring having a CrN-type hard coating as thick as 10-60 μm formed on its outer peripheral sliding surface, comprising the steps of
- adjusting the surface roughness Rzjis82 of the outer peripheral surface of a piston ring base material to 0.5-3 μm;
- alternately forming CrN layers and CrCN layers containing C dissolved in CrN by arc ion plating to form a CrN/CrCN laminate coating having a laminate unit composed of said CrN layer and said CrCN layer being as thick as 30-100 nm;
- and then
- grinding said CrN/CrCN laminate coating to form an outermost surface of said outer peripheral sliding surface having a composite structure comprising a CrN phase and a CrCN phase containing C dissolved in CrN.
Dependencies are inferred from the claim text.