US4301020A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process of slurrying and spray drying ceramic oxides with polyethyleneimine dispersants
Assignee: AT&T Inc
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Filing: 1981-02-06
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Granted: 1981-11-17
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Expires: 2001-02-06
Abstract
Abstract Many ceramics are produced with a processing sequence that includes spray drying or ball milling a slurry. To produce ceramics with the best properties and to facilitate ball milling or spray drying, a dispersant is normally added to the ceramic slurry. Ammonium citrate and polyethylenimine have been found to produce ceramic slurries with the desired characteristics. The dispersants appear especially well suited for use with ferrite slurries.
Inventors
- 👤 David W. Johnson, Jr.
- 👤 Eva M. Vogel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:52
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/26; C04B35/2658; C04B35/2608; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/34; H01F1/36
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
70 words
A method of processing ceramics which comprises forming a slurry consisting of ceramic material and a dispersant; said ceramic material forming between 65 percent and 80 percent, by weight, of said material and being a mixture of metal oxides, and spray drying said slurry; characterized in that said dispersant consists essentially of at least one member selected from the group consisting of polyethylenimine and mixtures of polyethylenimine and ammonium citrate.
Claim 2
Independent Claim
70 words
A method of processing ceramics which comprises forming a slurry consisting of ceramic material and a dispersant; said ceramic material forming between 65 percent and 80 percent, by weight, of said material and being a mixture of metal oxides, and spray drying said slurry; characterized in that said dispersant consists essentially of at least one member selected from the group consisting of polyethylenimine and mixtures of polyethylenimine and ammonium citrate.
Claim 3
Dependent Claim
19 words
A method as recited in claim 1 in which said slurry has a solids content of approximately 75 percent.
Claim 4
Dependent Claim
22 words
A method as recited in claim 2 in which said ceramic material is a mixture of oxides suitable for forming a ferrite.
Claim 5
Dependent Claim
15 words
A method as recited in claim 3 in which said ferrite is a MnZn ferrite.
Claim 6
Dependent Claim
23 words
A method as recited in claim 3 in which said dispersant is polyethylenimine, said dispersant having a concentration greater than 0.25 weight percent.
Claim 7
Dependent Claim
18 words
A method as recited in claim 5 in which said concentration is between 0.75 and 1.00 weight percent.
References Cited (Backward Citations)
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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) | 1984-11-16 | 1985-05-18 | 1985-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-16 | 1989-05-18 | 1989-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-16 | 1993-05-18 | 1993-11-17 | $7700.00 | Window Closed / Lapsed |