US4508563A
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Reducing the oxygen content of tantalum
Assignee: Vishay Sprague Inc
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Filing: 1984-03-19
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Granted: 1985-04-02
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Expires: 2004-03-19
Abstract
Abstract The oxygen content of tantalum is reduced by intimately contacting the tantalum with an alkali metal halide, reacting them in a non-oxidizing atmosphere at a maximum temperature of 1200 DEG C. to form and expel the tantalum halide and alkali metal oxide formed by the reaction, and then raising the temperature to 1400 DEG C. for no longer than 10 min. to volatilize any excess alkali metal halide. The tantalum may be in the form of a powder or a porous sintered pellet, and an improved product for electrolytic capacitors, with lower leakage current, is obtained.
Inventors
- 👤 Walter J. Bernard
- 👤 Richard J. Millard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:47
CPC Classifications
H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; H01G9/048; H01G9/052; H01G9/0525; B; B22; B22F; B22F1/00; B22F1/14; B22F1/145; C; C22; C22B; C22B34/00; C22B34/20; C22B34/24
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
82 words
A process for reducing the oxygen content of tantalum to obtain a high CV product for electrolytic capacitors comprising intimately contacting said tantalum with an alkali metal halide, reacting said metal halide with said tantalum oxide out of contact with an oxygenated medium at a temperature of at most 1200° C. to form a corresponding alkali metal oxide, and then increasing said temperature to at most 1400° C. for at most 10 minutes to volatilize and expel any excess alkali metal halide.
Claim 2
Dependent Claim
82 words
A process for reducing the oxygen content of tantalum to obtain a high CV product for electrolytic capacitors comprising intimately contacting said tantalum with an alkali metal halide, reacting said metal halide with said tantalum oxide out of contact with an oxygenated medium at a temperature of at most 1200° C. to form a corresponding alkali metal oxide, and then increasing said temperature to at most 1400° C. for at most 10 minutes to volatilize and expel any excess alkali metal halide.
Claim 3
Dependent Claim
21 words
A process according to claim 1 wherein said tantalum is in the form of powder particles having a thin oxide coating.
Claim 4
Dependent Claim
13 words
A process according to claim 2 wherein said intimate contacting is dry mixing.
Claim 5
Dependent Claim
17 words
A process according to claim 2 wherein said reacting is carried out prior to agglomerating said powder.
Claim 6
Dependent Claim
18 words
A process according to claim 1 wherein said tantalum is in the form of a sintered porous pellet.
Claim 7
Dependent Claim
22 words
A process according to claim 5 wherein said intimate contacting comprises impregnating said pellet with an aqueous solution of said metal halide.
Claim 8
Dependent Claim
28 words
A process according to claim 6 wherein said impregnated pellet is dried at up to 110° C. and for up to 60 minutes prior to said reacting step.
Claim 9
Dependent Claim
17 words
A process according to claim 1 wherein said reacting is carried out at least at 350° C.
Claim 10
Dependent Claim
29 words
A process according to claim 1 wherein said alkali metal halide is selected from the group consisting of bromide, chloride, and fluoride of sodium, potassium, lithium, cesium, and rubidium.
Claim 11
Dependent Claim
18 words
A process according to claim 9 wherein said alkali metal halide is a sodium, potassium, or lithium halide.
Claim 12
Dependent Claim
12 words
A process according to claim 9 wherein said halide is potassium fluoride.
Claim 13
Dependent Claim
16 words
A process according to claim 1 wherein said reacting is carried out in an inert atmosphere.
Claim 14
Dependent Claim
12 words
A process according to claim 12 wherein said inert atmosphere is helium.
Claim 15
Dependent Claim
15 words
A process according to claim 1 wherein said reacting is carried out under a vacuum.
Claim 16
Dependent Claim
20 words
A process according to claim 1 wherein said volatilizing of said alkali metal halide is carried out in a vacuum.
Claim 17
Dependent Claim
16 words
A process according to claim 15 wherein said pressure is reduced to approximately 10 -5 torr.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-04-01 | 1988-10-01 | 1989-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-01 | 1992-10-01 | 1993-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-01 | 1996-10-01 | 1997-04-02 | $7700.00 | Window Closed / Lapsed |