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US4954169A
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Fine-grained, high-purity earth acid metal powders, a process for their production and their use
Assignee: H.C. Starck GmbH
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Filing: 1989-06-12
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Granted: 1990-09-04
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Expires: 2009-06-12
Abstract
Abstract Earth acid metal powders, such as tantalum or niobium, useful in the production of electrolytic capacitors and other electronic components, are agglomerates of sintered compacts, wherein the mean grain size of the agglomerates is no more than 2.0 mu m, determined by the Fisher Sub-Sieve Sizer, and wherein the agglomerates consist of primary individual agglomerated particles of mean grain size of no more than 0.7 mu m.
Inventors
- 👤 Dieter Behrens
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:53
CPC Classifications
B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; H; H01; H01G; H01G9/00; H01G9/004; H01G9/04; H01G9/048; H01G9/052; H01G9/0525; B22F9/20; C; C22; C22B; C22B34/00; C22B34/20; C22B34/24; C22B5/00; C22B5/02; C22B5/04
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
57 words
Earth acid metal powders consisting of agglomerates for powder metallurgical applications for the production of sintered compacts, wherein the mean grain size of the agglomerates is no more than 2.0 μm, determined by the Fisher Sub-Sieve Sizer, and wherein the agglomerates consist of primary individual agglomerated particles of mean grain size of no more than 0.7 μm.
Claim 2
Dependent Claim
57 words
Earth acid metal powders consisting of agglomerates for powder metallurgical applications for the production of sintered compacts, wherein the mean grain size of the agglomerates is no more than 2.0 μm, determined by the Fisher Sub-Sieve Sizer, and wherein the agglomerates consist of primary individual agglomerated particles of mean grain size of no more than 0.7 μm.
Claim 3
Dependent Claim
21 words
Earth acid metal powders as claimed in claim 1 wherein 100% of the agglomerates pass through a 250 μm mesh sieve.
Claim 4
Dependent Claim
28 words
Earth acid metal powders as claimed in claim 1 which have a total alkali content of at most 30 ppm, and a potassium content not exceeding 10 ppm.
Claim 5
Dependent Claim
38 words
Earth acid metal powders as claimed in claim 1 which have a total content of iron, chromium and nickel of at most 30 ppm, and which have chromium and nickel contents not exceeding 5 ppm in either case.
Claim 6
Dependent Claim
16 words
Earth acid metal powders as claimed in claim 1 wherein the earth acid metal is tantalum.
Claim 7
Dependent Claim
42 words
Earth acid metal powders as claimed in claim 5, which when sintered for 20 minutes at 1500° C. have a specific electrical charge of more than 25 millicoulombs per gram and a volume-related charge of at least 120 millicoulombs per cubic centimeter.
Claim 8
Dependent Claim
32 words
Earth acid metal powders as claimed in claim 5, wherein the specific surface of the primary tantalum powder as measured by the BET method is at least 1.5 square meter per gram.
Claim 9
Dependent Claim
45 words
A process for the production of the earth acid metal powders claimed in claim 1 which comprises reacting alkali/earth acid double halides or earth acid halides with an alkali metal, wherein the reaction is carried out so that the reaction mixture is not a melt.
Claim 10
Dependent Claim
24 words
A process as claimed in claim 8, said halides contain tantalum or niobium and the reaction is carried out at temperatures below 600° C.
Claim 11
Dependent Claim
17 words
A process as claimed in claim 9 wherein the reaction temperatures is from 400° to 600° C.
Claim 12
Dependent Claim
25 words
A process as claimed in claim 9, wherein the halides are alkali heptafluorotantalates or alkali heptafluoroniobates and the reacting alkali metals are liquid alkali metals.
Claim 13
Dependent Claim
19 words
A process as claimed in claim 8 wherein the reaction is in the presence of inert alkali metal halides.
Claim 14
Dependent Claim
21 words
A process as claimed in claim 8 wherein the halide is potassium heptafluorotantalate and the reacting alkali metal is liquid sodium.
Claim 15
Dependent Claim
21 words
A process as claimed in claim 8 wherein the halide is sodium heptafluorotantalate and the reacting alkali metal is liquid sodium.
Claim 16
Dependent Claim
45 words
Sintered electrodes of the metal powders as claimed in claim 1 which after being sintered for 20 minutes at 1500° C. have a specific electrical charge of more than 25 millicoulombs per gram and a volume-related charge of at least 120 millicoulombs per cubic centimeter.
Claim 17
Dependent Claim
9 words
Sintered electrodes according to claim 15 which are anodes.
Claim 18
Dependent Claim
14 words
Electrolytic capacitors which contain the earth acid metal powders as claimed in claim 1.
Claim 19
Dependent Claim
13 words
Electrolytic capacitors according to claim 17 wherein the earth acid metal is tantalum.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-03 | 1994-03-05 | 1994-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-03 | 1998-03-05 | 1998-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-03 | 2002-03-05 | 2002-09-04 | $7700.00 | Window Closed / Lapsed |