Piston ring, and method for manufacturing same
A piston ring includes a substrate, and a film covering at least a part of a surface of the substrate. The film includes Si and N. A Si content of the film is in a range of 1.1 to 7.5 at %, a crystallite size of the film is in a range of 10 to 30 nm, and a compressive residual stress of the film is 400 to 800 MPa.
1. A piston ring comprising:
a substrate; and
a film covering at least a part of a surface of the substrate,
wherein the film comprises Cr, Si and N, and
wherein:
a Si content of the film is in a range of 1.1 to 7.5 at %,
a crystallite size of the film is in a range of 10 to 30 nm, and
a compressive residual stress of the film is 400 to 800 MPa.
2. A method for manufacturing the piston ring according to claim 1 , the method comprising:
cleaning the surface of the substrate of the piston ring; and
forming the film comprising Cr, Si and N in a chamber using a physical vapor deposition method so as to cover at least the part of the surface of the substrate,
wherein a nitrogen pressure in the chamber is set in a range of 2 to 6 Pa,
wherein the film is formed with a bias voltage set in a range of −5 to −18 V, and
wherein:
the Si content of the film is in a range of 1.1 to 7.5 at %,
the crystallite size of the film is in a range of 10 to 30 nm, and
the compressive residual stress of the film is 400 to 800 MPa.
3. The method according to claim 2 , wherein a hardness of the film is 1000 HV0.1 to 1800 HV0.1.
4. The piston ring according to claim 1 , wherein a Cr content of the film is 40 at % or more.
5. The piston ring according to claim 1 , wherein a texture coefficient of CrN (111) of the film is 0.4 or more.
6. The piston ring according to claim 1 , wherein a hardness of the film is 1000 HV0.1 to 1800 HV0.1.
7. The piston ring according to claim 1 , wherein a ratio H/E of a hardness H (GPa) of the film obtained by a nanoindenter, to a Young's modulus E (GPa) of the film is 0.04 to 0.07.
8. The piston ring according to claim 1 , wherein the crystallite size of the film is in a range of 15 to 30 nm.
9. The piston ring according to claim 1 , wherein the Si content of the film is in a range of 2.0 to 5.0 at %.
10. The method according to claim 2 , wherein the crystallite size of the film is in a range of 15 to 30 nm.
11. The method according to claim 2 , wherein the Si content of the film is in a range of 2.0 to 5.0 at %.
12. A film to cover a substrate of a piston ring, the film comprising Cr, Si and N,
wherein a Si content of the film is in a range of 1.1 to 7.5 at %,
wherein the film has a crystallite size in a range of 10 to 30 nm, and
wherein the film has a compressive residual stress of 400 to 800 MPa.
13. The film according to claim 12 ,
wherein a Cr content of the film is 40 at % or more, and
wherein a texture coefficient of CrN (111) of the film is 0.4 or more.
14. The film according to claim 12 , wherein the crystallite size of the film is in a range of 15 to 30 nm.
15. The film according to claim 12 , wherein the Si content of the film is in a range of 2.0 to 5.0 at %.
16. The film according to claim 12 , wherein the film has a hardness of 1000 HV0.1 to 1800 HV0.1.
17. The film according to claim 12 , wherein a ratio H/E of a hardness H (GPa) of the film obtained by nanoindenter, to a Young's modulus E (GPa) of the film is 0.04 to 0.07.
18. The film according to claim 12 , wherein the crystallite size of the film is in a range of 15 to 30 nm, as determined on a CrN (200) plane.
19. The piston ring according to claim 1 , wherein the crystallite size of the film is in a range of 15 to 30 nm, as determined on a CrN (200) plane.