Method for creating porous structures by particle expansion
A process for producing a metal foam. The process includes mechanically working a metallic powder such that oxide particles are finely dispersed within a metallic matrix of the metallic particles that make up the metallic powder. The mechanically worked metallic powder is then annealed in a reducing atmosphere, which in turn reduces the oxide particles within the metallic particles such that H 2 O gas molecules (steam) are formed within the metallic matrix and intraparticle porosity is produced.
1. A process for producing a metal foam comprising:
mechanically working a metallic powder such that oxide particles are finely dispersed within a metallic matrix; and
annealing the mechanically worked metallic powder in a reducing atmosphere, the annealed metallic powder having intraparticle porosity formed by chemical conversion of the oxide particles into steam.
2. The process of claim 1 , wherein the metallic powder is a copper containing metallic powder.
3. The process of claim 2 , wherein the mechanical working is ball milling the metallic powder.
4. The process of claim 3 , wherein the ball milling alloys copper particles with non-copper particles.
5. The process of claim 4 , wherein the non-copper particles are antimony particles.
6. The process of claim 3 , wherein the ball milling is cryogenic ball milling.
7. The process of claim 3 , wherein the ball milling is room temperature ball milling.
8. The process of claim 1 , wherein the reducing atmosphere is an argon-hydrogen atmosphere.
9. The process of claim 1 , wherein the annealing occurs at a temperature less than or equal to 800° C.
10. The process of claim 9 , wherein the annealing occurs at a temperature less than or equal to 700° C.
11. The process of claim 10 , wherein the annealing occurs at a temperature less than or equal to 600° C.
12. The process of claim 1 , further comprising compacting the annealed ball milled metallic powder into a desired shape, the desired shape having a porosity of at least 40%.
13. The process of claim 12 , wherein the porosity is at least 50%.
14. The process of claim 13 , wherein the porosity is at least 60%.
15. The process of claim 14 , wherein the porosity is at least 65%.
16. A process for a metal foam component comprising:
providing a plurality of metallic particles, each of the plurality of metallic particles having a metallic matrix;
ball milling the plurality of metallic particles such that oxide particles are finely dispersed within the metallic matrix of at least a portion of the metallic particles;
annealing the mechanically worked metallic powder in a reducing atmosphere containing hydrogen, the oxide particles reacting with the hydrogen to form steam and form intraparticle porosity within the metallic matrix of the at least a portion of the metallic particles; and
sintering the annealed mechanically worked metallic powder into a desired shape, the desired shape having a metal foam structure with a porosity of at least 40%.
17. The process of claim 16 , wherein the ball milling is cryogenic ball milling.
18. The process of claim 16 , wherein the ball milling is room temperature ball milling.
19. The process of claim 16 , wherein the annealing occurs at a temperature less than or equal to 700° C.
20. The process of claim 16 , wherein the porosity is at least 60%.