High-temperature low-friction cobalt-free coating system for gate valves, ball valves, stems, and seats

1. An apparatus for controlling well fluids, the apparatus comprising:

a gate valve having a body, the body having a cavity and a flow passage intersecting the cavity;

a seat ring mounted to the body at the intersection of the flow passage and the cavity, the seat ring having an engaging face formed of a steel alloy;

a gate in the cavity and having an engaging face formed of a steel alloy that slidingly engages the face of the seat ring while being moved between open and closed positions;

a hardened outer layer formed on the engaging face of the seat ring, the hardened layer formed of a Cobalt-free feedstock material and the hardened layer comprising Tungsten Carbide in a Cobalt-free matrix;

a friction-resistant coating of diamond-like carbon on the hardened outer layer, and

wherein the hardened layer exhibits two cracks or fewer per square inch, has an adhesion of 9,000 psi or greater, and has a porosity of 2 volume % or less.

2. The apparatus of claim 1 , wherein the Cobalt-free feedstock material comprises, in wt. %:

Ni: Balance

C: 0.5-2;

Cr: 10-30;

Mo: 5.81-18.2;

Nb+Ti: 2.38-10.

3. The apparatus of claim 1 , wherein the Cobalt-free feedstock material comprises, in wt. %:

Ni: Balance

C: about 0.84-about 1.56;

Cr: about 14-about 26;

Mo: about 8.4-about 15.6;

Nb: about 4.2-about 7.8; and

Ti: about 0.35-about 0.65.

4. The apparatus of claim 1 , wherein the Cobalt-free feedstock material comprises, in wt. %:

Ni: Balance

C: about 1.08-about 1.32;

Cr: about 13-about 22;

Mo: about 10.8-about 13.2; and

Nb: about 5.4-about 6.6.

5. The apparatus of claim 1 , wherein the Cobalt-free matrix of the hardened layer comprises a Nickel matrix comprising:

hard phases of 1,000 Vickers hardness or greater totaling 5 mol. % or greater;

20 wt. % or greater of a combined total of Chromium and Molybdenum;

isolated hypereutectic hard phases totaling to 50 mol. % or more of a total hard phase fraction;

a WC/Cr 3 C 2 ratio of 0.33 to 3;

an ASTM G65A abrasion loss of less than 250 mm 3 ; and

a Vickers hardness of 650 or greater.

6. The apparatus of claim 1 , wherein the hardened layer has a Vickers hardness of 750 or greater.

7. The apparatus of claim 1 , wherein the hardened layer has a porosity of 0.5 volume % or less.

8. The apparatus of claim 1 , wherein the hardened layer has a corrosion rate of 1 mpy or less in a 28% CaCl 2 ) electrolyte, pH=9.5 environment.

9. The apparatus of claim 5 , wherein the hardened layer has a corrosion rate that is less than 0.1 mpy in a 3.5% sodium chloride solution for 16 hours according to ASTM G59/ASTM G61.

10. The apparatus of claim 5 , wherein the Nickel matrix has a matrix proximity of 80% or greater as compared to a corrosion-resistant alloy defined by Ni: BAL, X>20 wt. %, wherein X represents at least one of Cu, Cr, or Mo.

11. The apparatus of claim 10 , wherein the corrosion-resistant alloy comprises an alloy having simple formula Ni30Cu.

12. The apparatus of claim 1 , wherein the hardened layer is a component of a hydraulic cylinder, tension riser, mud motor rotor, or oilfield component application.

13. The apparatus of claim 1 , wherein the Cobalt-free matrix forms a corrosion-resistant matrix, and under thermodynamic equilibrium conditions, the corrosion-resistant matrix has:

hard phases totaling 50 mol. % or greater; and

a liquidus temperature of 1550 K or lower.

14. The apparatus of claim 1 , wherein the Cobalt-free feedstock material comprises a blend of an alloy having simple formula Ni30Cu, and at least one of WC or Cr 3 C 2 .

15. The apparatus of claim 1 , wherein the Cobalt-free feedstock material is selected from the group consisting of, by wt.:

75-85% WC+15-25% Nickel-Copper alloy;

65-75% WC+25-35% Nickel-Copper alloy;

60-75% WC+25-40% Nickel-Copper alloy;

75-85% Cr 3 C 2 +15-25% Nickel-Copper alloy;

65-75% Cr 3 C 2 +25-35% Nickel-Copper alloy;

60-75% Cr 3 C 2 +25-40% Nickel-Copper alloy;

75-85% WC/Cr 3 C 2 +15-25% Nickel-Copper alloy;

65-75% WC/Cr 3 C 2 +25-35% Nickel-Copper alloy; and

60-75% WC/Cr 3 C 2 +25-40% Nickel-Copper alloy;

where the Nickel-Copper alloy is an alloy having simple formula Ni30Cu.

16. The apparatus of claim 13 , wherein a WC/Cr 3 C 2 ratio of the corrosion-resistant matrix is 0.2 to 5 by volume.

17. The apparatus of claim 1 , wherein the hardened layer comprises:

an ASTM G65A abrasion loss of less than 250 mm 3 ; and

two cracks or fewer per square inch when forming the hardened layer from a PTA or laser cladding process.

18. The apparatus of claim 17 , wherein the hardened layer comprises an impermeable HVOF coating which exhibits a corrosion rate of 1 mpy or less in a 28% CaCl 2 ) electrolyte, pH=9.5 environment.

19. The apparatus of claim 18 , wherein the hardened layer further comprises:

a Vickers hardness of 650 or greater; and

an adhesion of 9,000 psi or greater when forming the hardened layer from a HVOF thermal spray process.

20. The apparatus of claim 17 , wherein the hardened layer comprises:

a Vickers hardness of 750 or greater; and

a porosity of 0.5 volume % or less when forming the hardfacing layer from a HVOF thermal spray process.

21. The apparatus of claim 1 , wherein the coating of diamond-like carbon has a thickness of up to 30 microns.

22. A method of manufacturing the apparatus of claim 1 , the method comprising:

thermally spraying the tungsten carbide in the Cobalt-free feedstock to produce the hardened layer; and

applying the friction-resistant coating of diamond-like carbon to the hardened layer.

23. The method of claim 22 , further comprising applying a lubricant to the diamond-like layer.

24. The method of claim 22 , wherein the Cobalt-free feedstock is at least one of nickel feedstock, copper feedstock, and nickel-copper feedstock.

25. The method of claim 22 , wherein the coating of diamond-like carbon has a thickness of up to 30 microns.