Polycrystalline diamond linear bearings

1. A linear bearing assembly, the assembly comprising:

a linear bearing comprising a polycrystalline diamond bearing element, wherein the polycrystalline diamond bearing element has a polycrystalline diamond bearing surface, the polycrystalline diamond bearing surface having a surface finish of at most 20 μin Ra;

an opposing component, the opposing component having a metal bearing surface thereon, the metal bearing surface comprising a metal containing at least 2 weight percent of diamond solvent-catalyst based on a total weight of the metal;

wherein the linear bearing is movably coupled with the opposing component such that the polycrystalline diamond bearing surface is engaged with the metal bearing surface.

2. The assembly of claim 1 , wherein the polycrystalline diamond bearing surface has a surface finish of less than 2 μin Ra.

3. The assembly of claim 1 , wherein the metal bearing surface is hardened, plated, coated, or cladded.

4. The assembly of claim 1 , wherein the metal of the metal bearing surface comprises from 55 to 100 wt. % of the diamond solvent-catalyst based on the total weight of the metal.

5. The assembly of claim 1 , wherein the diamond solvent-catalyst is selected from the group consisting of: iron, cobalt, nickel, ruthenium, rhodium, palladium, chromium, manganese, copper, titanium, tantalum, and combinations thereof.

6. The assembly of claim 1 , wherein the metal is softer than a superhard material.

7. The assembly of claim 1 , wherein the linear bearing assembly is lubricated.

8. The assembly of claim 1 , wherein the linear bearing assembly is non-lubricated.

9. The assembly of claim 1 , wherein the polycrystalline diamond bearing surface is in direct contact with the metal bearing surface.

10. The assembly of claim 1 , wherein a fluid film is positioned between the polycrystalline diamond bearing surface and the metal bearing surface.

11. The assembly of claim 1 , wherein the polycrystalline diamond bearing surface is flush with a surface of a body of the linear bearing.

12. The assembly of claim 1 , wherein the polycrystalline diamond bearing surface is raised above a surface of a body of the linear bearing.

13. The assembly of claim 1 , wherein the polycrystalline diamond bearing surface is planar, convex, or concave.

14. The assembly of claim 1 , wherein the polycrystalline diamond bearing element is positioned such that a surface of a body of the linear bearing is maintained in a spaced-apart relationship from the metal bearing surface.

15. The assembly of claim 1 , wherein the polycrystalline diamond bearing element is raised above a surface of a body of the linear bearing, and wherein the metal bearing surface is a concavity in the opposing component.

16. The assembly of claim 1 , wherein the linear bearing has a second opposing bearing surface thereon, wherein the opposing component has a second polycrystalline diamond bearing element thereon, and wherein a polycrystalline diamond bearing surface of the second polycrystalline diamond bearing element is engaged with the second opposing bearing surface.

17. The assembly of claim 1 , wherein the linear bearing is a hollow cylinder including an annulus, wherein the opposing component is a tubular positioned within the annulus of the hollow cylinder, and wherein an outer surface of the tubular is the metal bearing surface.

18. The assembly of claim 1 , wherein the opposing component is a hollow cylinder with the metal bearing surface defining an annulus of the hollow cylinder, wherein the linear bearing is a tubular positioned within the annulus of the hollow cylinder.

19. The assembly of claim 1 , wherein the polycrystalline diamond bearing element has at least one curved or beveled edge.

20. A method of bearing load, the method comprising:

providing a linear bearing comprising a polycrystalline diamond bearing element, wherein the polycrystalline diamond bearing element has a polycrystalline diamond bearing surface having a surface finish of at most 20 μin Ra;

providing an opposing component having a metal bearing surface thereon, the metal bearing surface comprising a metal containing at least 2 weight percent of diamond solvent-catalyst based on a total weight of the metal;

movably coupling the linear bearing with the opposing component such that the polycrystalline diamond bearing surface is engaged with the metal bearing surface.

21. The assembly of claim 1 , further comprising:

wherein the linear bearing comprises a plurality of polycrystalline diamond bearing elements, wherein each polycrystalline diamond bearing element has a polycrystalline diamond bearing surface with a surface finish of at most 20 μin Ra;

wherein the linear bearing is movably coupled with the opposing component such that each of the polycrystalline diamond bearing surfaces are engaged with the metal bearing surface.

22. The assembly of claim 1 , wherein engagement between the linear bearing and the opposing component exhibits a coefficient of friction of less than 0.1.

23. The assembly of claim 1 , wherein the polycrystalline bearing element comprises a polycrystalline diamond compact.

24. A linear bearing assembly, the assembly comprising:

a linear bearing comprising a polycrystalline diamond bearing element, wherein the polycrystalline diamond bearing element has a polycrystalline diamond bearing surface, the polycrystalline diamond bearing surface having a surface finish of at most 20 μin Ra;

an opposing component, the opposing component having a metal bearing surface thereon, the metal bearing surface comprising a metal containing at least 2 weight percent of iron, cobalt, nickel, ruthenium, rhodium, palladium, chromium, manganese, copper, titanium, tantalum, or combinations thereof, based on a total weight of the metal;

wherein the linear bearing is movably coupled with the opposing component such that the polycrystalline diamond bearing surface is engaged with the metal bearing surface.