Energy conversion device and method of reducing friction therein
A device configured for converting energy includes a first surface, a second surface configured for moving with respect to the first surface during operation of the device, and a coating disposed on at least one of the first surface and the second surface. The coating includes a first layer of a ceramic alloy represented by the general formula AlMgB 14 —X, wherein X is present in an amount of from 0 to 70 parts by weight based on 100 parts by weight of the ceramic alloy and is a doping agent selected from the group of Group IV elements and borides and nitrides thereof, and a second layer disposed on the first layer and including carbon in a gradient concentration. The coating has a hardness of from 10 to 20 GPa and a coefficient of friction of less than or equal to 0.12.
1. A device configured for converting energy, the device comprising:
a first surface;
a second surface configured for moving with respect to said first surface during operation of the device; and
a coating disposed on at least one of said first surface and said second surface, said coating including;
a first layer of a ceramic alloy represented by the general formula AlMgB 14 —X;
wherein X is present in an amount of from 0 to 70 parts by weight based on 100 parts by weight of said ceramic alloy and is a doping agent selected from the Group IV elements and borides and nitrides thereof; and
a second layer disposed on said first layer and including:
said ceramic alloy; and
carbon present in an amount of from about 1 part by weight to 90 parts by weight based on 100 parts by weight of said second layer, and in a gradient concentration that increases with a distance from said first layer; and
wherein said coating has a hardness of from 10 to 20 GPa;
wherein said coating has a coefficient of friction of less than or equal to 0.12.
2. The device of claim 1 , wherein said device is a vane pump including a vane disposed within a ring.
3. The device of claim 2 , wherein at least one of said first surface and said second surface is an edge of said vane.
4. The device of claim 2 , wherein at least one of said first surface and said second surface is a surface of said ring.
5. The device of claim 2 , wherein a mechanical efficiency of said vane pump is increased by at least 2% when operated at a pressure of from 250 to 2,500 psi as compared to a vane pump that is substantially free from said coating.
6. The device of claim 2 , wherein said vane pump is substantially free from gouging after operating at a speed of about 1,800 rpm at a pressure of from 250 to 3,000 psi and a temperature of from 150 to 165° F. for approximately 240 minutes.
7. The device of claim 1 , wherein said device is an axial piston pump including a plate and a piston that is disposed within a cylinder barrel and adjacent a piston shoe.
8. The device of claim 7 , wherein at least one of said first surface and said second surface is a surface of said piston.
9. The device of claim 7 , wherein at least one of said first surface and said second surface is a surface of said cylinder barrel.
10. The device of claim 7 , wherein at least one of said first surface and said second surface is a surface of said plate.
11. The device of claim 7 , wherein at least one of said first surface and said second surface is a surface of said piston shoe.
12. The device of claim 1 , wherein said device is an orbital motor that is configured to be driven by a drive.
13. The device of claim 12 , wherein at least one of said first surface and said second surface is a surface of a roller of said orbital motor.
14. The device of claim 12 , wherein at least one of said first surface and said second surface is a surface of a ring of said orbital motor.
15. The device of claim 12 , wherein at least one of said first surface and said second surface is a surface of a plate of said orbital motor.
16. The device of claim 12 , wherein at least one of said first surface and said second surface is a surface of a valve of said orbital motor.
17. The device of claim 12 , wherein a mechanical efficiency at start-up of said orbital motor is increased by at least 4% as compared to an orbital motor that is substantially free from said coating including X present in an amount of from 0 to 70 parts by weight based on 100 parts of said ceramic alloy.
18. A method of reducing friction between a first surface and a second surface configured for moving with respect to the first surface, the method comprising the steps of:
forming a first layer of a ceramic alloy represented by the general formula AlMgB 14 —X on at least one of the first surface and the second surface;
wherein X is present in an amount of from 0 to 70 parts by weight based on 100 parts by weight of the ceramic alloy and is a doping agent selected from the Group IV elements and borides and nitrides thereof; and
depositing a second layer onto the first layer to thereby form a coating on at least one of the first surface and the second surface that reduces friction between the first surface and the second surface, wherein the second layer includes:
the ceramic alloy; and
carbon present in an amount of from about 1 part by weight to 90 parts by weight based on 100 parts by weight of the second layer, and in a gradient concentration that increases with a distance from the first layer;
wherein the coating has a hardness of from 10 to 20 GPa;
wherein the coating has a coefficient of friction of less than or equal to 0.12.
19. The method of claim 18 , wherein said depositing is further defined as sputtering the first layer with a target material including carbon.
20. The method of claim 18 , wherein said depositing is further defined as decomposing a carbon-based gas in the presence of the first layer.