USH189H
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for production of alpha alumina bodies by sintering seeded boehmite made from alumina hydrates
Assignee: Saint Gobain Abrasives Inc
•
Filing: 1985-07-16
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Granted: 1987-01-06
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Expires: 2005-07-16
Abstract
Abstract Inexpensive hydrates of alumina are used for the production of dense, submicron alumina bodies by conversion of the alumina hydrates to a soluble form which is then used to produce a boehmite gel. The boehmite gel, with very small particles of alpha alumina intimately dispersed therein is dried and fired to 1300° C. to 1450° C.
Inventors
- 👤 Ralph Bauer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 00:27
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/1115; C09; C09K; C09K3/00; C09K3/14; C09K3/1409
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
99 words
A method of making articles containing submicron alpha alumina in at least one phase, comprising (1) dissolving alumina hydrate in nitric acid, (2) converting the thus formed aluminum salt to boehmite having a crystal size below 100×10 -10 meters by nuetralization with ammonia, converting said boehmite to a gel by acidification, and firing said gel in the presence of at least 0.5% by weight of alpha alumina submicron seed particles to a temperature less than 1450° C. for a time such that the thus formed alpha alumina phase has an average crystal size of less than 0.5×10 -6 meters.
Claim 2
Independent Claim
99 words
A method of making articles containing submicron alpha alumina in at least one phase, comprising (1) dissolving alumina hydrate in nitric acid, (2) converting the thus formed aluminum salt to boehmite having a crystal size below 100×10 -10 meters by nuetralization with ammonia, converting said boehmite to a gel by acidification, and firing said gel in the presence of at least 0.5% by weight of alpha alumina submicron seed particles to a temperature less than 1450° C. for a time such that the thus formed alpha alumina phase has an average crystal size of less than 0.5×10 -6 meters.
Claim 3
Dependent Claim
33 words
A method as in claim 1 in which the aqueous aluminous salt solution formed in step (1) is neutralized with ammonium hydroxide to form boehmite having a crystal size below 100×10 -10 meters.
Claim 4
Dependent Claim
57 words
A method as in claim 1 in which the aluminum salt is a nitrate salt and is dried and fired to increase the Al 2 O 3 lNO 3 ratio to at least 2.5 to 1 and then autoclaved at 150° to 300° C. to produce boehmite having a crystal size of less than 150×10 -10 meters.
Claim 5
Dependent Claim
19 words
A method as in claim 1 in which the alumina hydrate is in the form of naturally occuring ore.
Claim 6
Dependent Claim
12 words
A method as in claim 4 in which the ore is bauxite.
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) | 1990-01-05 | 1990-07-07 | 1991-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-05 | 1994-07-07 | 1995-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-05 | 1998-07-07 | 1999-01-06 | $7700.00 | Window Closed / Lapsed |