Additive manufacturing of functionally gradient degradable tools

1. An article comprising a plurality of micro-sized or nano-sized galvanic cells, wherein the article has a seamless structure encompassing a plurality of empty spaces of different sizes, geometries, distributions, or a combination thereof, and one or more of the following properties of the article vary in different directions: tensile strength; compressive strength; electrical resistance; thermal conductance; modulus; or hardness.

2. The article of claim 1 , wherein each of the micro-sized or nano-sized galvanic cells comprises an anode and a cathode,

the anode comprising one or more of the following: a magnesium-based alloy; an aluminum-based alloy; a zinc-based alloy; or a manganese-based alloy; and

the cathode comprising a metal; an oxide of the metal; a nitride of the metal; or a cermet of the metal; wherein the metal is one or more of the following: W; Co; Cu; Ni; or Fe.

3. The article of claim 1 , wherein the article is a hollow frac plug, a hollow ball, or a hollow ball seat.

4. A method of manufacturing the article of claim 1 , the method comprising:

depositing a metallic powder on a substrate or a worktable; and

fusing the metallic powder according to a preset pattern

to additively form the article such that the article comprises a plurality of micro-sized or nano-sized galyanic cells, wherein the article has the seamless structure encompassing the plurality of empty spaces of different sizes, geometries, distributions, or a combination thereof, and one or more of the following properties of the article vary in different directions: tensile strength; compressive strength; electrical resistance; thermal conductance; modulus; or hardness.

5. The method of claim 4 , wherein the depositing and the fusing are carried out as part of a selective laser sintering process, a laser melting process, or a direct metal deposition process.

6. The method of claim 4 , wherein fusing the metallic powder comprises applying an energy beam from an energy source to the metallic powder.

7. The method of claim 4 , wherein the metallic powder is at least partially fused before deposited on the substrate or the worktable.

8. The method of claim 4 , wherein the metallic powder is fused after deposited on the substrate or the worktable.

9. The method of claim 4 , wherein the metallic powder comprises an uncoated metallic matrix particle and a second particle;

the metallic matrix particle comprising one or more of the following: a magnesium-based alloy; an aluminum-based alloy; or a zinc-based alloy; and

the second particle comprising one or more of the following: a metal; an oxide of the metal; a nitride of the metal; or a cermet of the metal; wherein the metal is W; Co; Cu; Ni; or Fe.

10. The method of claim 4 , wherein the metallic powder comprises a coated particle and optionally a second particle that is compositionally different from the coated particle; the coated particle having a particle core with a nanoscale coating disposed thereon, wherein the nanoscale coating has a melting point different than a melting point of the particle core.

11. The method of claim 10 , wherein the particle core comprises one or more of the following: Mg; Al; Zn; Mn, or an alloy thereof.

12. The method of claim 10 , wherein the nanoscale coating comprises one or more of the following: Al; Zn; Mn; Mg; Mo; W; Cu; Fe; Si; Ca; Co; Ta; Re; or Ni; an oxide thereof; a carbide thereof; or a nitride thereof.

13. The method of claim 10 , wherein the second particle comprises one or more of the following: Fe; Ni; Co; W; or Cu; or oxides; nitrides; or carbides thereof.

14. The method of claim 4 , further comprising adjusting a composition of the metallic powder or a condition to fuse the metallic powder or a combination thereof to additively form the article.

15. The method of claim 14 , wherein adjusting a composition of the metallic powder comprises changing the relative amounts of the coated particle and the second particle.

16. The method of claim 14 , wherein adjusting a composition of the metallic powder comprises varying a particle size of the coated particle, varying a particle size of the second particle, or a combination thereof.

17. The method of claim 14 , wherein adjusting a condition to fuse the metallic powder comprises fusing the metallic powder at an energy gradient.

18. A method of using the article of claim 1 , the method comprising:

providing the article of claim 1 , the article comprising a first portion and a second portion, the second portion having a higher porosity than the first portion;

engaging the first portion of the article with an object under load;

performing an operation; and

corroding away the article by exposing the article to a fluid.

19. The method of claim 18 , wherein the article is a downhole article, the fluid is a wellbore fluid, and the operation is a wellbore operation.