Controlled oxygen addition for metal material
View Patent ↗Methods to form metal oxide material are described. In one process, an oxide film on a metal material is diffused throughout the metal material to form a preferred uniform metal oxide material. The present invention further relates to products formed by the process. Also, the present invention relates to the use of the products in capacitor anodes and other applications.
1. A method to form a metal oxide powder comprising diffusing oxygen from a metal oxide film present on a metal powder formed into a pressed article to form said metal oxide powder having a form of said pressed article, wherein said diffusing takes place in an inert atmosphere, or in a hydrogen atmosphere, or in a vacuum, wherein the metal of said metal oxide film and the metal of said metal powder are the same, wherein an anodic oxide film is formed on the pressed article to form said metal oxide film, and wherein said metal powder is niobium and said metal oxide film is niobium pentoxide.
2. The method of claim 1 , wherein said anodic oxide film is formed by applying a voltage of from about 10 volts to about 100 volts to said metal powder to form said anodic oxide film.
3. The method of claim 2 , wherein said voltage is from about 10 to about 80 volts.
4. The method of claim 1 , wherein said metal oxide powder is NbO.
5. The method of claim 1 , wherein said metal oxide powder has an atomic ratio of niobium to oxygen of less than 2:1.
6. A method to form a metal oxide powder comprising forming an oxide film on a metal powder formed into a pressed article; and
diffusing oxygen from said oxide film through said metal powder to form said metal oxide powder having a form of said pressed article, and wherein said diffusing takes place in an inert atmosphere, or in a hydrogen atmosphere, or in a vacuum, and wherein the metal of said metal oxide film and the metal of said metal powder are the same, wherein an anodic oxide film is formed on the pressed article to form said oxide film, and wherein said metal powder is niobium and said oxide film is niobium pentoxide.
7. The method of claim 6 , wherein said diffusing is achieved by heat treating said metal powder.
8. The method of claim 7 , wherein said heat treating is at a temperature of at least 200° C. for a sufficient time to diffuse said oxygen from said oxide film to at least a portion of said metal powder.
9. The method of claim 8 , wherein said heat treating is at a temperature of from about 200 to about 1500° C.
10. The method of claim 6 , wherein said metal oxide powder is completely formed throughout said pressed article.
11. The method of claim 6 , wherein said diffusing is partial wherein a metal oxide powder is formed and is present with a portion of said metal powder.
12. The method of claim 6 , wherein said oxygen diffuses through a portion of said metal powder to form a metal oxide powder and a core of metal powder is not converted to a metal oxide powder.
13. The method of claim 6 , further comprising reanodizing said metal oxide powder to form an oxide film on said metal oxide powder.
14. The method of claim 6 , wherein said metal oxide powder is NbO.
15. The method of claim 6 , wherein said metal oxide powder has an atomic ratio of niobium to oxygen of less than 2:1.
16. The method of claim 15 , further comprising reanodizing said metal oxide powder to form an oxide film on said metal oxide powder.
17. A method to form a metal oxide powder comprising diffusing oxygen from a metal oxide film present on a metal powder formed into a pressed article to form said metal oxide powder having a form of said pressed article, wherein said diffusing takes place in an inert atmosphere, or in a hydrogen atmosphere, or in a vacuum, and wherein the metal of said metal oxide film and the metal of said metal powder are the same, wherein said pressed article is reduced to a powder after said oxide film is present and after said diffusing takes place, wherein an anodic oxide film is formed on the pressed article to form said metal oxide film, and wherein said metal powder is niobium and said metal oxide film is niobium pentoxide.
18. The method of claim 17 , wherein said metal oxide powder is NbO.
19. A method to form a metal oxide powder comprising diffusing oxygen from a metal oxide film present on a metal powder formed into a pressed article to form said metal oxide powder having a form of said pressed article, wherein said diffusing takes place in an inert atmosphere, or in a hydrogen atmosphere, or in a vacuum, and wherein the metal of said metal oxide film and the metal of said metal powder are the same, wherein said pressed article is reduced to a powder after said metal oxide film is present and prior to said diffusing takes place, and wherein said diffusing is achieved by heat treating said metal powder.