Degradable metal matrix composite

1. A method for forming a degradable composite comprising:

a. providing a plurality of ceramic or intermetallic particles having a hardness greater than 50 HRC;

b. providing one or more galvanically active elements selected from the group consisting of iron, nickel, copper, cobalt, titanium silver, gold, gallium, bismuth, palladium, carbon, and indium;

c. combining said plurality of ceramic or intermetallic particles and said one or more galvanically-active elements;

d. adding a molten degradable metal matrix to said plurality of ceramic or intermetallic particles and said one or more galvanically-active elements, said molten degradable metal matrix including greater than 50 wt. % magnesium and aluminum;

e. dispersing said plurality of ceramic or intermetallic particles and said one or more galvanically-active elements in said molten degradable metal matrix; and

f. cooling said degradable metal matrix to form said degradable composite, said degradable composite having a surface regression rate of at least 0.02 mm/hr. at 35° C. to 200° C. in 100-100,000 ppm freshwater or brine, said degradable composite having a hardness of greater than 22 Rockwell C, said composite including at least 10 vol. % degradable metal matrix, at least 0.03 vol. % galvanically-active elements, and at least 20 vol. % ceramic or intermetallic particles.

2. The method as defined in claim 1 , wherein said plurality of ceramic or intermetallic particles are coated with said one or more galvanically-active elements prior to said addition of said molten degradable metal matrix to said plurality of ceramic or intermetallic particles and said one or more galvanically-active elements.

3. The method as defined in claim 1 , wherein the ceramic or intermetallic particles include one or more types of particles selected from metal carbides, borides, oxides, silicides, or nitrides such as B 4 C, TiB 2 , TiC, Al 2 O 3 , MgO, SiC, Si 3 N 4 , ZrO 2 , SiB 6 , SiAlON, or WC.

4. The method as defined in claim 1 , wherein the ceramic or intermetallic particles have a particle size of 0.1 microns to 1000 microns.

5. The method as defined in claim 1 , wherein at least a portion of the ceramic or intermetallic particles are shards, fragments, preformed or machined shapes, or flakes with a maximum dimension of 0.1-4 mm.

6. The method as defined in claim 1 , wherein said galvanically-active elements include one or more elements selected from the group consisting of nickel, iron, cobalt, titanium, and copper.

7. The method as defined in claim 1 , wherein said composite is greater than a 92% pore-free structure.

8. The method as defined in claim 1 , wherein said composite is deformed and/or heat treated to improve mechanical properties of said composite, reduce porosity of said composite, and/or form net shape or near net shape dimensions of said composite.

9. The method as defined in claim 1 , wherein the composite formed into a degradable structure is useful in oil and gas or other subterranean operations, said degradable structure including a seat, seal, ball, frac ball, cone, wedge, insert for a slip, sleeve, frac seat, grip, slip, valve, valve component, spring, retainer, scraper, poppet, penetrator, perforator, shear, ring, blade, insert, or other component requiring wear-, erosion-, or deformation-resistance, edge retention, or high hardness.

10. The method as defined in claim 1 , wherein said composite is a surface coating or cladding for a component.

11. A method for forming a degradable composite, said method comprises:

a. providing a plurality of ceramic or intermetallic particles having a hardness greater than 50 HRC;

b. providing one or more galvanically active elements selected from the group consisting of calcium, barium, lithium, sodium, potassium, iron, nickel, copper, cobalt, titanium silver, gold, gallium, bismuth, lead, palladium, carbon, and indium;

c. combining said plurality of ceramic or intermetallic particles and said one or more galvanically-active elements, said ceramic or intermetallic particles having a particle size of 0.1-1000 microns;

d. adding a molten degradable metal matrix to said plurality of ceramic or intermetallic particles and said one or more galvanically-active elements, said molten degradable metal matrix selected from i) a magnesium alloy including greater than 50 wt. % magnesium, and ii) an aluminum alloy including greater than 50 wt. % aluminum;

e. dispersing said plurality of ceramic or intermetallic particles and said one or more galvanically-active elements in said molten degradable metal matrix; and

f. cooling said degradable metal matrix to form said degradable composite, said degradable composite having a degradation rate of at least 5 mg/cm 2 /hr. at 35° C. in 100-100,000 ppm freshwater or brine, said degradable composite having a hardness of greater than 22 Rockwell C, said composite including at least 10 vol. % degradable metal matrix, at least 0.03 vol. % galvanically-active elements, and at least 10 vol. % ceramic or intermetallic particles.

12. The method as defined in claim 11 , wherein said ceramic or intermetallic particles include one or more materials selected from the group consisting of B 4 C, TiB 2 , TiC, Al 2 O 3 , MgO, SiC, Si 3 N 4 , ZrO 2 , ZrSiO 4 , SiB 6 , SiAlON, WC, carbon ferrochrome, Cr 2 O 3 , and chrome carbide.

13. The method as defined in claim 11 , wherein said degradable composite has a hardness of greater than 30 Rockwell C.

14. The method as defined in claim 11 , wherein said ceramic or intermetallic particles are surface coated with a metal prior to being mixed with said molten degradable metal matrix, said metal including one or more materials selected from the group consisting of nickel, zirconium, niobium, vanadium, chromium, iron, cobalt, titanium, copper, magnesium, zinc, aluminum, tin, and titanium, said coating having a thickness of 60 nm to 100 microns.

15. The method as defined in claim 11 , wherein said degradable metal matrix is a magnesium alloy including greater than 50 wt. % magnesium, said magnesium alloy including one or more metal additive selected from the group consisting of nickel, copper, aluminum, boron, bismuth, zinc, zirconium, cobalt, manganese, titanium, and iron.

16. The method as defined in claim 11 , said method further includes the step of coating said degradable composite with a protective coating, said protective coating less than 3 mm, said protective coating including a polymer layer.

17. The method as defined in claim 11 , said method further includes the step of adding flakes, fibers, or platelets to said mixture of said molten degradable metal matrix, said ceramic or intermetallic particles, and said galvanically-active elements, said flakes fibers or platelets having an aspect ratio of at least 4:1, a length of said flakes, fibers, or platelets up to 4 mm, said flakes, fibers, or platelets including one or more materials selected from the group consisting of boron carbide, silicon carbide, and graphite.

18. The method as defined in claim 11 , wherein a compression strength of said degradable composite is greater than 40 ksi.

19. The method as defined in claim 11 , said method further includes the step of deforming and/or heat treating said degradable composite to develop improved mechanical properties, reduce porosity, or to form net shape or near net shape dimensions.

20. The method as defined in claim 19 , wherein said degradable composite is formed partially or fully into a structure useful in oil and gas or other subterranean operations, said structure including a seat, seal, ball, frac ball, cone, wedge, insert for a slip, sleeve, valve, frac seat, sleeve, grip, slip, valve, valve component, spring, retainer, scraper, poppet, penetrator, perforator, shear, blade, and insert.