Method of making niobium and other metal powders
View Patent ↗Methods of forming niobium powders and other metal powders are described. The method involves milling the metal powders at elevated temperatures and in the presence of at least one liquid solvent. The methods of the present invention have the ability to reduce DC leakage and/or increase capacitance capabilities of metal powders when formed into capacitor anodes. The present invention further has the ability to significantly reduce the milling time necessary to form high surface area metal powders and leads to reducing the amount of contaminants in the metal powders. Metal powders such as niobium powders having reduced amount of contaminants and/or having DC leakage or capacitance capabilities are also described. A process is further described for forming a flaked metal by wet-milling a metal powder into a flaked metal wherein at least one liquid fluorinated fluid is present during the wet-milling process. The process is particularly well suited for forming metal flakes, such as niobium or tantalum flakes, of high purity.
1. A niobium powder having a carbon content of from about 40 ppm to about 200 ppm and a iron, nickel, and chromium content of from about 5 ppm to about 200 ppm, wherein said niobium powder has a flow of greater than 80 mg/s; and
wherein said niobium powder is agglomerated and has a Scott density of less than about 35 g/in 3 ; or
wherein said niobium powder is unagglomerated and has a Scott density of less than about 12 g/in 3 .
2. The niobium powder of claim 1 , wherein said carbon amount is from about 50 to about 150 ppm.
3. A niobium powder having a carbon amount of from about 40 to about 200 ppm when the BET surface area is about 1.0 m 2 /g and a carbon amount of less than 250 ppm when the BET surface area of the niobium powder is from about 2 to about 4.5 m 2 /g and the combined amount of Fe/Ni/Cr is less than 100 ppm when the BET surface area of the niobium powder is about 1.0 m 2 /g and less than about 400 ppm when the BET surface area of the niobium powder is from about 2.0 m 2 /g to about 4.5 m 2 /g;
wherein said niobium powder is agglomerated and has a Scott density of less than about 35 g/in 3 ; or
wherein said niobium powder is unagglomerated and has a Scott density of less than about 12 g/in 3 .
4. A capacitor anode comprising the niobium powder of claim 1 .
5. A capacitor anode comprising the niobium powder of claim 2 .
6. A capacitor anode comprising the niobium powder of claim 3 .
7. The niobium powder of claim 1 , wherein said niobium powder is flaked.
8. The niobium powder of claim 3 , wherein said niobium powder is flaked.
9. The niobium powder of claim 1 , wherein said niobium powder has a BET surface area of from about 1.0 m 2 /g to about 4.5 m 2 /g.
10. The niobium powder of claim 1 , wherein said niobium powder has a BET surface area of at least 0.15 m 2 /g.
11. The niobium powder of claim 1 , wherein said niobium powder further comprises oxygen, phosphorous, or both.
12. The niobium powder of claim 1 , wherein said niobium powder is agglomerated.
13. The niobium powder of claim 3 , wherein said niobium powder has a flow of greater than 80 mg/s.
14. The niobium powder of claim 1 , wherein the niobium powder has a flow of from about 80 mg/s to about 500 mg/s.
15. The niobium powder of claim 1 , wherein said niobium powder has a BET surface area of from about 1 m 2 /g to about 10.0 m 2 /g.
16. The niobium powder of claim 1 , wherein said niobium powder has a shape which is flake, angular, nodular, or mixtures thereof.
17. The niobium powder of claim 1 , wherein said niobium powder has a shape that is nodular.
18. The niobium powder of claim 1 , wherein said niobium powder has a BET surface area of from about 6 m 2 /g to about 15 m 2 /g.
19. The niobium powder of claim 1 , wherein said niobium powder has an oxygen content of about 2,000 ppm or below.
20. The niobium powder of claim 1 , wherein said niobium powder has an oxygen content of from about 2,000 ppm to about 60,000 ppm.
21. The niobium powder of claim 1 , wherein said niobium powder further comprises phosphorous in the amount of less than about 400 ppm.
22. The niobium powder of claim 1 , wherein said niobium powder comprises nitrogen.
23. The niobium powder of claim 1 , wherein said niobium powder comprises nitrogen in an amount of at least 300 ppm.
24. The capacitor anode of claim 4 , wherein said anode has a capacitance of at least about 62,000 CV/g.
25. The capacitor anode of claim 4 , wherein said anode has a capacitance of at least about 70,000 CV/g.
26. The capacitor anode of claim 4 , wherein said anode has a capacitance of from about 65,000 CV/g to about 250,000 CV/g.
27. The capacitor anode of claim 4 , wherein said anode is formed at a voltage of less than about 60 volts.
28. The capacitor anode of claim 4 , wherein said anode has a working voltage of from about 4 to about 16 volts.
29. The capacitor anode of claim 4 , wherein said anode has a DC Leakage of less than about 5.0 na/CV.
30. The capacitor anode of claim 4 , wherein said anode has a formation voltage of from about 50 to about 80 volts.
31. The capacitor anode of claim 4 , wherein said anode has a working voltage of from about 10 to about 20 volts.
32. A hydrided niobium powder having a carbon content of from about 40 ppm to about 200 ppm and a iron, nickel, and chromium content of from about 5 ppm to about 200 ppm.
33. The hydrided niobium powder of claim 32 , wherein said carbon amount is from about 50 to about 150 ppm.
34. The hydrided niobium powder of claim 32 , wherein said niobium powder has a BET surface area of from about 1.0 m 2 /g to about 4.5 m 2 /g.
35. The hydrided niobium powder of claim 32 , wherein said niobium powder has a BET surface area of at least 0.15 m 2 /g.
36. The hydrided niobium powder of claim 32 , wherein said niobium powder further comprises oxygen, phosphorous, or both.
37. The hydrided niobium powder of claim 32 , wherein said niobium powder is agglomerated.
38. The hydrided niobium powder of claim 32 , wherein said niobium powder is agglomerated and has a Scott density of less than about 35 g/in 3 .
39. The hydrided niobium powder of claim 32 , wherein said niobium powder is unagglomerated and has a Scott density of less than about 12 g/in 3 .
40. The hydrided niobium powder of claim 32 , wherein said niobium powder has a flow of greater than 80 mg/s.
41. The hydrided niobium powder of claim 32 , wherein the niobium powder has a flow of from about 80 mg/s to about 500 mg/s.
42. The hydrided niobium powder of claim 32 , wherein said niobium powder has a BET surface area of from about 1 m 2 /g to about 10.0 m 2 /g.
43. The hydrided niobium powder of claim 32 , wherein said niobium powder has a shape which is flake, angular, nodular, or mixtures thereof.
44. The hydrided niobium powder of claim 32 , wherein said niobium powder has a shape that is nodular.
45. The hydrided niobium powder of claim 32 , wherein said niobium powder has a BET surface area of from about 6 m 2 /g to about 15 m 2 /g.
46. The hydrided niobium powder of claim 32 , wherein said niobium powder has an oxygen content of about 2,000 ppm or below.
47. The hydrided niobium powder of claim 32 , wherein said niobium powder has an oxygen content of from about 2,000 ppm to about 60,000 ppm.
48. The hydrided niobium powder of claim 32 , wherein said niobium powder further comprises phosphorous in the amount of less than about 400 ppm.
49. The hydrided niobium powder of claim 32 , wherein said niobium powder comprises nitrogen.
50. The hydrided niobium powder of claim 32 , wherein said niobium powder comprises nitrogen in an amount of at least 300 ppm.
51. The niobium powder of claim 3 , wherein said niobium powder has an oxygen content of about 2,000 ppm or below.
52. The niobium powder of claim 3 , wherein said niobium powder has an oxygen content of from about 2,000 ppm to about 60,000 ppm.