Piston ring and method of manufacture
A piston ring includes a split annular body having an outer circumferential surface, an intermediate coating on the outer circumferential surface, a first layer on the intermediate coating, the first layer having a first hardness and a first porosity, and a second layer on the first layer, the second layer having a second hardness that is less than the first hardness, and having a second porosity that is greater than the first porosity.
1. A piston ring, comprising:
a split annular body having an outer circumferential surface;
an intermediate coating directly in contact with the outer circumferential surface;
a tribological coating forming an outermost coating of the piston ring, comprising:
a first layer in direct contact with the intermediate coating, the first layer having a first hardness and a first porosity, wherein the first layer includes one of an amorphous carbon and a diamond-like carbon-based material; and
a second layer in direct contact with the first layer, the second layer having a second hardness that is less than the first hardness, and having a second porosity that is greater than the first porosity, wherein the second layer has the same chemical composition as the first layer.
2. The piston ring of claim 1 , wherein one of the first layer and the second layer includes one of a nitride of titanium, a nitride of zirconium, a nitride of vanadium, a nitride of niobium, a nitride of chromium, a nitride of molybdenum, and a nitride of tungsten.
3. The piston ring of claim 2 , wherein the other of the first layer and the second layer includes one of a nitride of titanium, a nitride of zirconium, a nitride of vanadium, a nitride of niobium, a nitride of chromium, a nitride of molybdenum, and a nitride of tungsten.
4. The piston ring of claim 1 , wherein the intermediate coating includes at least one of chromium, nickel, cobalt, titanium, and vanadium.
5. The piston ring of claim 1 , wherein a ratio of hardness between the second layer and the first layer is in a range of 0.5:1 to 0.7:1.
6. The piston ring of claim 1 , wherein the second layer includes a metal.
7. The piston ring of claim 1 , wherein the first layer includes a metal nitride.
8. The piston ring of claim 1 , wherein a ratio of hardness between the second layer and the first layer is in a range of 0.2:1 and 0.6:1.
9. The piston ring of claim 1 , wherein an outermost surface of the second layer of the tribological coating is free of any further coating material.
10. A piston ring, comprising:
a split annular body having an outer circumferential surface;
an intermediate coating directly in contact with the outer circumferential surface;
a tribological coating forming an outermost coating of the piston ring, comprising:
a first layer in direct contact with the intermediate coating, the first layer having a first hardness and a first porosity, wherein the first layer includes a metal nitride; and
a second layer in direct contact with the first layer, the second layer having a second hardness that is less than the first hardness, and having a second porosity that is greater than the first porosity, wherein the second layer has the same chemical composition as the first layer.
11. The piston ring of claim 10 , wherein one of the first layer and the second layer includes one of a nitride of titanium, a nitride of zirconium, a nitride of vanadium, a nitride of niobium, a nitride of chromium, a nitride of molybdenum, and a nitride of tungsten.
12. The piston ring of claim 11 , wherein the other of the first layer and the second layer includes one of a nitride of titanium, a nitride of zirconium, a nitride of vanadium, a nitride of niobium, a nitride of chromium, a nitride of molybdenum, and a nitride of tungsten.
13. The piston ring of claim 10 , wherein the intermediate coating includes at least one of chromium, nickel, cobalt, titanium, and vanadium.
14. The piston ring of claim 10 , wherein a ratio of hardness between the second layer and the first layer is in a range of 0.5:1 to 0.7:1.
15. The piston ring of claim 10 , wherein the first layer includes one of an amorphous carbon and a diamond-like carbon-based material.
16. The piston ring of claim 10 , wherein the second layer includes a metal.
17. The piston ring of claim 10 , wherein a ratio of hardness between the second layer and the first layer is in a range of 0.2:1 and 0.6:1.
18. The piston ring of claim 10 , wherein an outermost surface of the second layer of the tribological coating is free of any further coating material.
19. A piston ring, comprising:
a split annular body having an outer circumferential surface;
an intermediate coating directly in contact with the outer circumferential surface;
a tribological coating forming an outermost coating of the piston ring, comprising:
a first layer in direct contact with the intermediate coating, the first layer having a first hardness and a first porosity; and
a second layer in direct contact with the first layer, the second layer having a second hardness that is less than the first hardness, and having a second porosity that is greater than the first porosity, wherein the second layer has the same chemical composition as the first layer.
20. The piston ring of claim 19 , wherein the first layer includes an amorphous carbon, a diamond-like carbon-based material, and a metal nitride.