Cryogenic bearings
View Patent ↗The bearing system includes a first component having a first substrate and a first coating. The first coating includes a DLC layer and a DLN layer between the DLC layer and the substrate. A second component is in sliding engagement with the first component.
1. A bearing system comprising:
a first component having a first substrate and a first coating, the first coating comprising a DLC layer and a DLN layer between the DLC layer and the substrate; and
a second component having a second substrate and second coating in bearing engagement with the first component said bearing engagement consisting essentially of a sliding engagement, the second coating engaging the first coating via said sliding engagement.
2. The system of claim 1 wherein:
the first coating consists essentially of the DLC layer and the DLN layer.
3. The system of claim 1 wherein:
the first and second components are in the sliding engagement along an essentially radial intersection.
4. The system of claim 1 wherein:
the bearing system is a non-foil journal bearing.
5. The system of claim 1 wherein:
the second coating acts as a solid lubricant effective to provide a coefficient of friction of less than 0.2.
6. The system of claim 1 wherein:
the second coating comprises silver in an amount effective to act as a solid lubricant.
7. The system of claim 1 wherein:
the second coating has a thickness of 2-50 μm.
8. The system of claim 1 wherein:
the second coating has a thickness of 12.5-50 μm.
9. The system of claim 1 wherein:
the first coating has a characteristic thickness of 0.5-5.0 μm.
10. The system of claim 1 wherein:
the first coating has a characteristic thickness of 1.5-2.2 μm;
the DLC layer and the DLN layer each provide at least 25% of said characteristic thickness; and
a thinner of the DLC layer and the DLN layer is at least 25% of a thickness of the other.
11. The system of claim 1 wherein:
the first coating has a characteristic thickness of 0.5-2.0 μm.
12. The system of claim 1 wherein:
the first coating has a characteristic adherence of HF2 or stronger.
13. The system of claim 1 wherein:
the first substrate is titanium-based.
14. The system of claim 1 wherein:
the second substrate is a superalloy, comprising in major mass part one or more of iron, nickel, and cobalt.
15. The system of claim 1 wherein:
the second substrate comprises in largest mass part one of iron, nickel, and cobalt.
16. The system of claim 1 wherein:
the first substrate is a rotor of a turbopump; and
the second substrate is a bearing of a housing of the turbopump.
17. The system of claim 16 wherein:
the turbopump is driven by a first flow of a first fluid; and
the turbopump pumps a second flow of a second fluid at a temperature below −150° C.
18. A turbopump comprising:
a housing; and
a rotor carried by the housing for rotation about a rotor axis, the housing and rotor cooperating to define a first flow path for a first fluid to drive said rotation and a second flow
path for a second fluid to be pumped by the rotation; wherein:
a first of the housing and rotor has a first substrate and a first coating, the first coating comprising a DLC layer and a DLN layer between the DLC layer and the substrate; and
a second of the housing and rotor is in sliding engagement with the first, the second comprising a substrate and silver-based solid lubricant coating in said sliding engagement.
19. The turbopump of claim 18 in combination with a flow, consisting in major part of one of liquid oxygen, liquid hydrogen, kerosene, and hydrazine, along the second flow path as said second fluid.
20. The turbopump of claim 18 wherein:
the housing comprises, in major weight part, one or more superalloys comprising in major part at least one of iron, nickel, and cobalt; and
the rotor comprises, in major weight part, one or more titanium alloys.