Nanocomposite coatings for threaded connections
A coating which provides corrosion resistance, wear resistance, and, optionally, lubrication, for deposition on a threaded article is disclosed. The coating comprises a polymer matrix, such as a polyimide, which is modified with small amounts of a fluorine containing polymer modifier, as well as other compounds or additives to improve performance of the coating. Additionally, the coating can further comprise a solid lubricant or an anticorrosion compound dispersed within the polymer matrix.
1. A threaded article comprising:
a first coating composition deposited on a thread portion of the threaded article, comprising:
a polymer selected from the group consisting of epoxies and polyimides;
about 0.5 to about 15 wt. % of a fluorine containing polymer modifier;
about 5 to about 15 wt. % of an anticorrosion compound;
about 10 to about 15 wt. % of an adhesion additive comprising zinc oxide, said zinc oxide provided in an effective amount to promote adhesion of the first coating composition to the thread portion.
2. The threaded article of claim 1 , wherein the mean diameter of the zinc oxide ranges between approximately 10 nm to approximately 10 μm.
3. The threaded article of claim 1 , wherein the fluorine containing polymer modifier comprises perfluoropolyether.
4. The threaded article of claim 1 , wherein the first coating composition comprises a single layer.
5. The threaded article of claim 1 , wherein the first coating composition further comprises about 3 to about 30 wt. % of a solid lubricant.
6. The threaded article of claim 5 , wherein the solid lubricant is selected from the group consisting of graphite, molybdenum disulfide, HDPE and PTFE.
7. The threaded article of claim 1 , wherein the first coating composition further comprises at least one of:
about 3 to about 8 wt % zinc;
about 1 to about 5 wt. % zinc(II)phosphate;
about 1 to about 5 wt. % Carbon black; and
about 10 to about 20 wt. % of polydimethylsiloxane.
8. The threaded article of claim 1 , wherein a second coating composition layer comprising a dry film lubricant is deposited on a thread portion of at least one of a pin and a box members.
9. The threaded article of claim 8 , wherein the first coating composition is deposited on a pin member and the second coating composition is deposited on a box member.
10. The threaded article of claim 8 , wherein the second coating composition comprises:
about 4 to about 16 wt. % polytetrafluoroethylene (PTFE);
about 8 to about 24 wt. % of a reactive epoxy;
about 1 to about 6 wt. % titanium dioxide; and
a solvent;
wherein the amount of each component is on the basis of the total weight of the second coating composition.
11. The threaded article of claim 8 , wherein the combined thickness of the first and second coatings layers is less than about 80 μm.
12. The threaded article of claim 8 , wherein the thickness of the first and second coating compositions are approximately equal.
13. The threaded article of claim 1 , wherein the coating composition further comprises a reinforcement nano/micro particle additive.
14. The threaded article of claim 13 , wherein the reinforcement nano/micro particle additive is modified with organic functional groups.
15. The threaded article of claim 13 , wherein the reinforcement nano/micro particle additive comprises about 5 to 20 wt. % of the total weight of the coating composition.
16. The threaded article of claim 13 , wherein the reinforcement nano/micro particle additive is selected from the group consisting of silicon carbide, titanium dioxide, aluminum oxide, and silicon dioxide.
17. The threaded article of claim 16 , wherein the reinforcement nano/micro particle additive comprises SiC.
18. The threaded article of claim 17 , wherein the SiC comprises about 5-20% of the total weight of the coating composition.
19. The threaded article of claim 17 , wherein the SiC comprises about 5-10% of the total weight of the coating composition.
20. The threaded article of claim 1 , wherein the coating composition has a coefficient of friction of less than about 0.2.
21. The threaded joint of claim 20 , wherein the coefficient of friction is less than about 0.1.
22. The threaded article of claim 1 , wherein the coating composition has a surface roughness of about 0.29 to about 0.31 μm.
23. The threaded article of claim 22 , wherein the surface roughness is about 0.3 μm.
24. The threaded article of claim 1 , wherein the coating composition passes the neutral salt spray test for about 500 h.
25. The threaded article of claim 1 , wherein the coating composition passes the cross-cut tape test according to ASTM D3359-02.
26. The threaded article of claim 1 , wherein substantially no corrosion occurs under blisters formed after about 500 h of SST according to DIN 50021/ASTM B117.
27. A threaded article comprising:
a dope-free coating composition deposited on a thread portion of the threaded article, comprising:
a polymer;
a fluorine containing polymer modifier dispersed within the polymer;
a reinforcement nano/micro particle additive dispersed within the polymer; and
a solid lubricant dispersed within the polymer;
wherein the coating composition has a wear coefficient of less than about 1.0×10 −5 mm 3 /N/m and a surface roughness of about 0.29 to about 0.31 μm.
28. The threaded article of claim 27 , wherein the polymer comprises a polyimide.
29. The threaded article of claim 27 , wherein the solid lubricant is selected from the group consisting of graphite, molybdenum disulfide, HDPE, and PTFE.
30. The threaded article of claim 27 , wherein the coating composition has a coefficient of friction of less than about 0.2.
31. The threaded joint of claim 30 , wherein the coefficient of friction is less than about 0.1.
32. The threaded article of claim 27 , wherein the reinforcement nano/micro particle additive is selected from the group consisting of silicon carbide, titanium dioxide, aluminum oxide, and silicon dioxide.
33. The threaded article of claim 27 , wherein the surface roughness is about 0.3 μm.
34. The threaded article of claim 27 , wherein the fluorine containing polymer modifier comprises perflouropolyether.
35. The threaded article of claim 27 , wherein the coating composition comprises about 0.5 to about 15 wt. % of the fluorine containing polymer modifier.
36. The threaded article of claim 27 , wherein the coating composition comprises about 5 to 20 wt. % of the reinforcement nano/micro particle additive.
37. The threaded article of claim 27 , wherein the coating composition comprises about 3 to 30 wt. % of the solid lubricant.
38. The threaded article of claim 27 , wherein the coating composition further comprises about 5 to about 15 wt. % of an anticorrosion compound.
39. The threaded article of claim 38 , wherein the coating composition passes the neutral salt spray test for about 500 h.
40. The threaded article of claim 38 , wherein the coating composition passes the cross-cut tape test according to ASTM D3359-02.
41. The threaded article of claim 38 , wherein substantially no corrosion occurs under blisters formed after about 500 h of SST according to DIN 50021/ASTM B117.
42. The threaded article of claim 27 , wherein the reinforcement nano/micro particle additive is modified with organic functional groups.
43. The threaded article of claim 32 , wherein the reinforcement nano/micro particle additive comprises SiC.
44. The threaded article of claim 43 , wherein the SiC comprises about 5-20% of the total weight of the coating composition.
45. The threaded article of claim 44 , wherein the SiC comprises about 5-10% of the total weight of the coating composition.