Piston ring for internal combustion engines
A piston ring for an internal combustion engine may include a substantially annular base of a ferrous alloy upon which is applied a coating. The coating may have a first bonding layer and at least a first external layer or a second external layer deposited upon the first bonding layer up to a maximum of 100 micrometers in thickness of a plurality of sequentially deposited first and second external layers. The first external layer may include a nitride of a doped metal chemical element, a doping element being aluminum. The second external layer may include a nitride of the metal chemical element. The first external layer may have a thickness greater than at least once a thickness of the second external layer and less than ten times the thickness of the second external layer.
1. A piston ring for an internal combustion engine comprising a substantially annular base of a ferrous alloy upon which is applied a coating having:
a first bonding layer, and
at least a first external layer or a second external layer deposited upon the first bonding layer up to a maximum of 100 micrometers in thickness of a plurality of sequentially deposited first and second external layers,
wherein the first external layer includes a nitride of a doped metal chemical element, doping element being aluminum,
wherein the second external layer includes a nitride of the metal chemical element,
wherein the first external layer has a thickness greater than at least once a thickness of the second external layer and less than ten times the thickness of the second external layer,
wherein the coating further comprises a second bonding layer deposited upon the first bonding layer.
2. The piston ring as claimed in claim 1 , wherein the metal chemical element is one of chromium, titanium, or niobium.
3. The piston ring as claimed in claim 1 , wherein the first and second external layers are each provided with a thickness of between 1 and 200 nanometers.
4. The piston ring as claimed in claim 1 , wherein the first bonding layer includes one of chromium or chromium/aluminum and the second bonding layer includes a doped chromium nitride, wherein a doping element is one of aluminum or a chromium nitride.
5. The piston ring as claimed in claim 1 , wherein the coating has a hardness between 1800 and 2500 HV.
6. The piston ring as claimed in claim 1 , wherein the coating has a porosity from 3% to 6%.
7. The piston ring as claimed in claim 1 , wherein the coating has an internal stress of between 200 and 700 MPa.
8. An internal combustion engine comprising at least one piston ring-having a substantially annular base of a ferrous alloy upon which is applied a coating having:
a first bonding layer, and
at least a first external layer or a second external layer deposited upon the first bonding layer up to a maximum of 100 micrometers in thickness of a plurality of sequentially deposited first and second external layers,
wherein the first external layer includes a nitride of a doped metal chemical element, a doping element being aluminum,
wherein the second external layer includes a nitride of the metal chemical element,
wherein the first external layer has a thickness greater than at least once a thickness of the second external layer and less than ten times the thickness of the second external layer, and
wherein the coating further comprises a second bonding layer deposited upon the first bonding layer.
9. The internal combustion engine as claimed in claim 8 , wherein the metal chemical element is one of chromium, titanium, or niobium.
10. The internal combustion engine as claimed in claim 8 , wherein the first bonding layer includes one of chromium or chromium/aluminum and the second bonding layer includes a doped chromium nitride, wherein a doping element is one of aluminum or a chromium nitride.
11. The internal combustion engine as claimed in claim 8 , wherein the coating has a hardness between 1800 and 2500 HV.
12. The internal combustion engine as claimed in claim 8 , wherein the coating has a porosity from 3% to 6%.
13. The internal combustion engine as claimed in claim 8 , wherein the coating has an internal stress of between 200 and 700 MPa.