Hydrophobic porous hard coating with lubricant, method for making and use of same

1. A composite comprising:

a porous matrix having a molybdenum-silicon-boron (Mo—Si—B) alloy, the Mo—Si—B alloy having a plurality of pores and comprising one or more of the following: α-Mo; Mo 3 Si; Mo 5 SiB 2 ; or Mo-20Si-10B; and

a lubricant in contact with the Mo—Si—B alloy, a hydrophobic compound in contact with the Mo—Si—B alloy, or a combination thereof;

wherein the lubricant is a solid lubricant and comprises one or more of the following: indium; tin; antimony; germanium; zinc; copper; boron nitride; graphene; or carbon nanotube; and further wherein an amount of the plurality of pores in the porous matrix is from 5 vol % to 40 vol %, based on a total volume of the porous matrix, and the average pore size is greater than or equal to 1 micron; and

wherein a strength of the composite is greater than or equal to 500 MPa at a temperature greater than or equal to 1000° C.

2. The composite of claim 1 , further comprising a substrate.

3. The composite of claim 2 , wherein the lubricant is disposed in a pore of the porous matrix, disposed on a surface of the porous matrix, disposed on a surface of the hydrophobic compound, disposed in the hydrophobic compound, or a combination thereof; and

the hydrophobic compound is disposed in a pore of the porous matrix, disposed on a surface of the porous matrix, disposed on a surface of the lubricant, disposed in the lubricant, or a combination thereof.

4. The composite of claim 1 , wherein the hydrophobic compound comprises a fluoropolymer comprising a repeat unit which comprises vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, chlorotrifluoroethylene, perfluoro(alkyl vinyl ether), perfluoro(ethyl vinyl ether), perfluoro(propyl vinyl ether), or a combination thereof.

5. The composite of claim 1 , wherein Mo is present in the Mo—Si—B alloy in an amount from 70 at % to 98 at %, based on a total atomic amount of Mo, Si, and B;

Si is present in the Mo—Si—B alloy in an amount from 2 at % to 25 at %, based on a total atomic amount of Mo, Si, and B; and

B is present in the Mo—Si—B alloy in an amount from 1 at % to 15 at %, based on a total atomic amount of Mo, Si, and B.

6. The composite of claim 1 , wherein the Mo—Si—B alloy is present in an amount from 30 wt % to 90 wt %, based on a total weight of the Mo—Si—B alloy, the lubricant, and the hydrophobic compound.

7. The composite of claim 6 , wherein the lubricant is present in an amount from 5 wt % to 30 wt %, and the hydrophobic compound is present in an amount from 0 wt % to 70 wt %, based on a total weight of the Mo—Si—B alloy, the lubricant, and the hydrophobic compound.

8. The composite of claim 1 , wherein a thickness of the porous matrix (Mo—Si—B) is from 20 μm to 200 μm.

9. The composite of claim 1 , wherein the composite is resistant to oxidation at a temperature greater than or equal to 1200° C.

10. The composite of claim 1 , wherein the composite is a downhole tool comprising a drill bit, cutter, tubular, slip, cable, housing, or seal.

11. The composite of claim 1 , wherein the Mo—Si—B alloy is present in an amount from 40 wt % to 90 wt %, the lubricant is present in an amount from 5 wt % to 30 wt %, the hydrophobic compound is present in an amount of 5 wt % to 30 wt %, each based on a total weight of the Mo—Si—B alloy, the lubricant, and the hydrophobic compound.

12. A method for preparing a porous composite, the method comprising:

disposing a porous matrix comprising a molybdenum-silicon-boron (Mo—Si—B) alloy on a substrate, the Mo—Si—B alloy comprising a plurality of pores and comprising one or more of the following: α-Mo; Mo 3 Si; Mo 5 SiB 2 ; or Mo-20Si-10B;

disposing a lubricant on a surface of the porous matrix; and

disposing a hydrophobic compound on a surface of the porous matrix to form the porous composite;

wherein the lubricant is a solid lubricant and comprises one or more of the following: indium; tin; antimony; germanium; zinc; copper; boron nitride; graphene; or carbon nanotube; and further wherein an amount of the plurality of pores in the porous matrix is from 5 vol % to 40 vol %, based on a total volume of the porous matrix, and the average pore size is greater than or equal to 1 micron; and

wherein a strength of the composite is greater than or equal to 500 MPa at a temperature greater than or equal to 1000° C.

13. The method of claim 12 , further comprising:

heating the porous composite;

flowing the lubricant in the plurality of pores; and

flowing the hydrophobic compound in the plurality of pores.

14. The process of claim 12 , further comprising:

contacting Mo—Si 3 N 4 with BN; and

forming a plurality of grains of the Mo—Si—B alloy;

heating the plurality of grains; and

consolidating the plurality of grains by applying pressure to produce a Mo—Si—B alloy compact,

wherein disposing the porous matrix on the substrate comprises:

removing a portion of the Mo—Si—B alloy; and

depositing the Mo—Si—B alloy on the substrate to form the porous matrix.

15. The process of claim 12 , further comprising:

consolidating a powder of the Mo—Si—B alloy; and

sintering the powder to produce a Mo—Si—B alloy compact,

wherein disposing the porous matrix on the substrate comprises:

removing a portion of the Mo—Si—B alloy; and

depositing the Mo—Si—B alloy on the substrate to form the porous matrix.

16. The method of claim 12 , wherein the lubricant is a solid lubricant having a melting temperature greater than or equal to 150° C.

17. The method of claim 12 , wherein the hydrophobic compound comprises a fluoropolymer;

the lubricant comprises a transition metal or post-transition metal; and

Si and B are present in the Mo—Si—B alloy in an amount respectively from 7 at % to 12 at % of Si and from 9 at % to 14 at % of B, with a balance being Mo, based on the total atomic amount Mo, Si, and B in the Mo—Si—B alloy.