Dynamic dehydriding of refractory metal powders
View Patent ↗Refractory metal powders are dehydrided in a device which includes a preheat chamber for retaining the metal powder fully heated in a hot zone to allow diffusion of hydrogen out of the powder. The powder is cooled in a cooling chamber for a residence time sufficiently short to prevent re-absorption of the hydrogen by the powder. The powder is consolidated by impact on a substrate at the exit of the cooling chamber to build a deposit in solid dense form on the substrate.
1. A method for dehydriding, the method comprising:
delivering a metal hydride powder to a converging-diverging nozzle;
heating the metal hydride powder, within the converging-diverging nozzle, thereby converting the metal hydride powder to a dehydrided metal powder within the converging-diverging nozzle,
wherein the dehydrided metal powder has a hydrogen content of 900 ppm or less;
cooling the dehydrided metal powder within the converging-diverging nozzle for a sufficiently small cooling time to prevent reabsorption of hydrogen into the metal powder;
and thereafter, depositing the dehydrided metal powder on a substrate to form a solid deposit.
2. The method of claim 1 , wherein the dehydrided metal powder is deposited on the substrate from a distance of less than approximately 10 mm.
3. The method of claim 1 , wherein heating of the metal hydride powder and the cooling of the dehydrided metal powder are performed under a positive pressure of an inert gas.
4. The method of claim 1 , wherein a hydrogen content of the metal hydride powder is greater than approximately 3900 ppm before heating.
5. The method of claim 1 , wherein the hydrogen content of the dehydrided metal powder is less than approximately 100 ppm after it is deposited.
6. The method of claim 1 , wherein the hydrogen content of the dehydrided metal powder is less than approximately 50 ppm after it is deposited.
7. The method of claim 1 , wherein the metal hydride powder comprises a refractory metal hydride powder.
8. The method of claim 1 , wherein an oxygen content of the solid deposit is less than approximately 200 ppm.
9. The method of claim 1 , wherein the dehydrided metal powder is deposited by spray deposition.
10. The method of claim 9 , wherein the dehydrided metal powder is deposited by cold spray.
11. The method of claim 1 , wherein a hydrogen content of the metal hydride powder decreases by at least two orders of magnitude during heating.
12. The method of claim 1 , wherein an oxygen content of the dehydrided metal powder does not increase during cooling.
13. The method of claim 1 , further comprising providing an inert gas within the nozzle.
14. The method of claim 1 , wherein the inert gas comprises helium.
15. The method of claim 1 , wherein the inert gas comprises argon.
16. A method for dehydriding, the method comprising:
providing nitrogen within a nozzle comprising converging and diverging portions;
heating a metal hydride powder in the nozzle to decrease a hydrogen content of the metal hydride powder, thereby forming a metal powder,
wherein the resulting metal powder has a hydrogen content of 900 ppm or less;
cooling the metal powder within the nozzle for a sufficiently small cooling time to prevent reabsorption of hydrogen into the metal powder; and
thereafter, depositing the metal powder on a substrate to form a solid deposit.
17. The method of claim 1 , wherein the metal hydride powder comprises tantalum hydride.
18. The method of claim 1 , wherein the metal hydride powder comprises niobium hydride.
19. The method of claim 1 , wherein the metal hydride powder comprises titanium hydride.
20. The method of claim 1 , wherein the metal hydride powder comprises zirconium hydride.
21. The method of claim 1 , wherein the dehydrided metal powder is cooled within the converging-diverging nozzle for less than 9 milliseconds.
22. The method of claim 1 , wherein the dehydrided metal powder is cooled within the converging-diverging nozzle for less than 0.5 milliseconds.
23. The method of claim 1 , wherein the dehydrided metal powder has the hydrogen content of 100 ppm or less.
24. The method of claim 1 , wherein the dehydrided metal powder has the hydrogen content of 50 ppm or less.
25. The method of claim 1 , wherein the dehydrided metal powder has the hydrogen content of 10 ppm or less.
26. The method of claim 1 , wherein the hydrogen content of the dehydrided metal powder is at least two orders of magnitude less than a hydrogen content of the metal hydride powder.
27. The method of claim 1 , further comprising providing nitrogen within the converging-diverging nozzle.
28. The method of claim 16 , wherein the hydrogen content of the metal powder is at least two orders of magnitude less than a hydrogen content of the metal hydride powder.
29. The method of claim 16 , wherein the metal powder has the hydrogen content of 100 ppm or less.
30. The method of claim 16 , wherein the metal powder has the hydrogen content of 16 ppm or less.
31. The method of claim 16 , wherein the metal powder has the hydrogen content of 10 ppm or less.
32. The method of claim 16 , wherein the metal powder is cooled within the nozzle for less than 9 milliseconds.
33. The method of claim 16 , wherein the metal powder is cooled within the nozzle for less than 0.5 milliseconds.
34. The method of claim 16 , wherein the metal powder is deposited by spray deposition.
35. The method of claim 34 , wherein the metal powder is deposited by cold spray.
36. The method of claim 16 , wherein the metal hydride powder comprises a refractory metal hydride powder.
37. The method of claim 16 , wherein the metal hydride powder comprises tantalum hydride.
38. The method of claim 16 , wherein the metal hydride powder comprises niobium hydride.
39. The method of claim 16 , wherein the metal hydride powder comprises titanium hydride.
40. The method of claim 16 , wherein the metal hydride powder comprises zirconium hydride.
41. The method of claim 16 , wherein the hydrogen content of the metal hydride powder is greater than approximately 3900 ppm before heating.