Patent US4835124A successfully refreshed from Google Patents.
US4835124A
Expired / Lapsed
US
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Alumina ceramic product from colloidal alumina
Assignee: ALMATIS Inc
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Filing: 1986-12-29
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Granted: 1989-05-30
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Expires: 2006-12-29
Abstract
Abstract Disclosed in a process for forming a ceramic body from colloidal boehmite and alpha alumina. Alpha alumina is added to the colloidal boehmite to produce a seeded gal, the seeded gel capable of being sintered at a low temperature to produce a ceramic product having at least a 90% theoretical density.
Inventors
- 👤 Alan Pearson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:47
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/1115; B; B82; B82Y; B82Y30/00; C01; C01F; C01F7/00; C01F7/02; C01F7/44; C01F7/447; C01F7/448; C01P; C01P2002/00; C01P2002/01; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/60; C01P2004/61; C01P2004/62; C01P2004/64; C01P2006/00; C01P2006/12
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
115 words
A process for forming a ceramic body from colloidal boehmite and alpha alumina comprising the steps of: (a) forming the colloidal boehmite by: (i) bringing the aluminum hydroxide selected from the group consisting of gibbsite, bayerite and nordstrandite together in a liquid aqueous medium with a seed effective for providing a base for boehmite growth; and (ii) hydrothermally digesting for producing colloidal boehmite by depositing boehmite on the seed at the expense of the aluminum hydroxide; (b) adding to said colloidal boehmite alpha alumina to produce a seeded gel, the seeded gel capable of being dried and then sintered at a low temperature to produce a ceramic product having at least a 90% theoretical density.
Claim 2
Dependent Claim
115 words
A process for forming a ceramic body from colloidal boehmite and alpha alumina comprising the steps of: (a) forming the colloidal boehmite by: (i) bringing the aluminum hydroxide selected from the group consisting of gibbsite, bayerite and nordstrandite together in a liquid aqueous medium with a seed effective for providing a base for boehmite growth; and (ii) hydrothermally digesting for producing colloidal boehmite by depositing boehmite on the seed at the expense of the aluminum hydroxide; (b) adding to said colloidal boehmite alpha alumina to produce a seeded gel, the seeded gel capable of being dried and then sintered at a low temperature to produce a ceramic product having at least a 90% theoretical density.
Claim 3
Dependent Claim
17 words
The process in accordance with claim 1 wherein the alpha alumina is added as a water slurry.
Claim 4
Dependent Claim
24 words
The process in accordance with claim 1 wherein the alpha alumina has a median particle size in the range of 0.05 to 2 micrometers.
Claim 5
Dependent Claim
20 words
The process in accordance with claim 2 wherein the slurry has a pH in the range of 2 to 5.
Claim 6
Dependent Claim
20 words
The process in accordance with claim 1 including the step of adding a gelling agent to produce said seeded gel.
Claim 7
Dependent Claim
20 words
The process in accordance with claim 1 wherein said gel is dried for a sufficient time to remove nitrates therefrom.
References Cited (Backward Citations)
US4224302A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-29 | 1992-11-28 | 1993-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-29 | 1996-11-28 | 1997-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-29 | 2000-11-28 | 2001-05-30 | $7700.00 | Window Closed / Lapsed |