Patent US3940510A successfully refreshed from Google Patents.
US3940510A
Expired / Lapsed
US
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Process for the manufacture of silver-coated tungsten carbide electrode material
Assignee: Siemens AG
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Filing: 1973-09-06
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Granted: 1976-02-24
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Expires: 1993-09-06
Abstract
Abstract The invention concerns a method for the manufacture of an electrode material containing silver-coated tungsten carbide for electrochemical cells, particularly fuel cells and storage cells. Silver is precipitated on finely-divided tungsten carbide particles by reduction of a silver salt, and the tungsten carbide particles are thereby joined to form particles of larger grain size.
Inventors
- 👤 Karl Hohne
- 👤 Konrad Mund
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:03
CPC Classifications
B; B01; B01J; B01J23/00; B01J23/38; B01J23/48; B01J23/50; B01J37/00; B01J37/16; H; H01; H01M; H01M4/00; H01M4/86; H01M4/90; Y; Y02; Y02E; Y02E60/00; Y02E60/30; Y02E60/50
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
97 words
A process for preparing silver-coated tungsten carbide particles adapted for use in manufacturing electrodes for fuel cells, which process comprises forming a suspension of finely divided particles of tungsten carbide in an alkaline solution, adding to said suspension a reducing agent capable of reducing silver ions in alkaline medium and also a silver salt soluble in said solution, the amounts of tungsten carbide and silver salt employed being sufficient to provide a silver content of approximately 10 to 20% by weight of said silver-coated tungsten carbide particles, and thereafter separating from said suspension silver-coated tungsten carbide particles.
Claim 2
Dependent Claim
97 words
A process for preparing silver-coated tungsten carbide particles adapted for use in manufacturing electrodes for fuel cells, which process comprises forming a suspension of finely divided particles of tungsten carbide in an alkaline solution, adding to said suspension a reducing agent capable of reducing silver ions in alkaline medium and also a silver salt soluble in said solution, the amounts of tungsten carbide and silver salt employed being sufficient to provide a silver content of approximately 10 to 20% by weight of said silver-coated tungsten carbide particles, and thereafter separating from said suspension silver-coated tungsten carbide particles.
Claim 3
Dependent Claim
26 words
A process according to claim 1, wherein said silver salt and said reducing agent are mixed together in solution prior to being added to said suspension.
Claim 4
Dependent Claim
12 words
The process according to claim 1, wherein said reducing agent is formaldehyde.
Claim 5
Dependent Claim
13 words
The process according to claim 1, wherein said silver salt is silver nitrate.
Claim 6
Dependent Claim
22 words
The process according to claim 2 wherein said solution of silver salt and reducing agent is an aqueous or weakly acid solution.
Claim 7
Dependent Claim
24 words
The process according to claim 1, wherein said suspension is vigorously agitated during the addition thereto of said silver salt and said reducing agent.
Claim 8
Dependent Claim
23 words
The process according to claim 1, wherein said fine-grained tungsten carbide particles have a mean grain size of less than about 1 micron.
Claim 9
Dependent Claim
36 words
The process according to claim 1 wherein the amount of tungsten carbide and silver salt employed is an amount sufficient to provide a silver content of approximately 15% by weight in said silver-coated tungsten carbide particles.
Claim 10
Dependent Claim
23 words
The process according to claim 1 in which said alkaline solution is one of the group consisting of potassium hydroxide and sodium hydroxide.
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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) | 1979-02-23 | 1979-08-25 | 1980-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-02-23 | 1983-08-25 | 1984-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-02-23 | 1987-08-25 | 1988-02-24 | $7700.00 | Window Closed / Lapsed |