Patent US5139978A successfully refreshed from Google Patents.
US5139978A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impregnation method for transformation of transition alumina to a alpha alumina
Assignee: 3M Co
•
Filing: 1990-07-16
•
Granted: 1992-08-18
•
Expires: 2010-07-16
Abstract
Abstract The method of the present invention is useful in preparing an improved alpha alumina-based ceramic. The improvement consists of the addition of a precursor of an alpha phase nucleating to transition alumina. The method is particularly useful in preparing alpha alumina-based abrasive grain.
Inventors
- 👤 Thomas E. Wood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:48
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/1115; C04B35/622; C04B35/62227; C04B35/62231; C09; C09K; C09K3/00; C09K3/14; C09K3/1409; C09K3/1418
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
154 words
A method of making an alpha alumina-based ceramic, having a seeded microstructure comprising alpha alumina domains nucleated with an alpha chromic oxide nucleating agent, said method comprising the steps of: a) preparing a liquid admixture which comprises a sufficient amount of a precursor of alpha chromic oxide that when converted to alpha chromic oxide nucleates the transformation of transition alumina to alpha alumina, wherein said alpha alumina has a seeded microstructure; b) impregnating said admixture of step (a) into a transition alumina-based body; c) drying said impregnated transition alumina body; d) calcining said dried impregnated transition alumina body at a temperature an in an atmosphere sufficient to substantially remove volatile materials and convert said precursor to its nucleating phase; and e) sintering said calcined-impregnated transition alumina body at a temperature and in an atmosphere sufficient to provide an alpha alumina-based ceramic having a seeded microstructure comprising alpha alumina domains nucleated with alpha chromic oxide.
Claim 2
Independent Claim
154 words
A method of making an alpha alumina-based ceramic, having a seeded microstructure comprising alpha alumina domains nucleated with an alpha chromic oxide nucleating agent, said method comprising the steps of: a) preparing a liquid admixture which comprises a sufficient amount of a precursor of alpha chromic oxide that when converted to alpha chromic oxide nucleates the transformation of transition alumina to alpha alumina, wherein said alpha alumina has a seeded microstructure; b) impregnating said admixture of step (a) into a transition alumina-based body; c) drying said impregnated transition alumina body; d) calcining said dried impregnated transition alumina body at a temperature an in an atmosphere sufficient to substantially remove volatile materials and convert said precursor to its nucleating phase; and e) sintering said calcined-impregnated transition alumina body at a temperature and in an atmosphere sufficient to provide an alpha alumina-based ceramic having a seeded microstructure comprising alpha alumina domains nucleated with alpha chromic oxide.
Claim 3
Dependent Claim
15 words
The method according to claim 1 wherein said alpha alumina ceramic has a well-seeded microstructure.
Claim 4
Dependent Claim
15 words
The method according to claim 1 wherein said liquid admixture is a molten metal salt.
Claim 5
Dependent Claim
12 words
The metal according to claim 1 wherein said liquid admixture is aqueous.
Claim 6
Dependent Claim
17 words
The method according to claim 1 wherein said precursor of a nucleating phase is a chromium-based salt.
Claim 7
Dependent Claim
13 words
The method according to claim 1 wherein said chromium-based salt is chromium nitrate.
Claim 8
Dependent Claim
17 words
The method according to claim 5 wherein said precursor of a nucleating phase is CrO 3 .
Claim 9
Dependent Claim
19 words
The method according to claim 1 wherein said admixture contains more than one precursor of an alpha alumina precursor.
Claim 10
Dependent Claim
20 words
The method according to claim 1 wherein steps (b), (c), and (d) are repeated in sequence up to 3 times.
Claim 11
Dependent Claim
37 words
The method according to claim 1 wherein said alpha alumina-based ceramic comprises in the range of about 4 to about 20 weight percent chromium, derived from alpha chromic oxide, based on the amount of alpha alumina present.
Claim 12
Dependent Claim
37 words
The method according to claim 1 wherein said alpha alumina-based ceramic comprises in the range of about 5 to about 8.5 weight percent chromium, derived from alpha chromic oxide, based on the amount of alpha alumina present.
Claim 13
Dependent Claim
16 words
The method according to claim 1 wherein said transition alumina contains at least one modifying additive.
Claim 14
Dependent Claim
14 words
The method according to claim 12 wherein said modifying additive is a metal-containing compound.
Claim 15
Independent Claim
36 words
The method according to claims 1, 12 or 13, wherein the total quantity of alumina, and chromium oxide present in said alpha alumina-based ceramic is at least 60 weight percent, based on the total ceramic composition.
Claim 16
Independent Claim
36 words
The method according to claims 1, 12 or 13, wherein the total quantity of alumina, and chromium oxide present in said alpha alumina-based ceramic is at least 90 weight percent, based on the total ceramic composition.
Claim 17
Dependent Claim
17 words
The method of claim 1 wherein the composition of said admixture is the same for each impregnation.
Claim 18
Dependent Claim
16 words
The method of claim 1 wherein the composition of said admixture is different for each impregnation.
Claim 19
Dependent Claim
66 words
The method according to claim 1 wherein said transition alumina body is prepared by a dispersion-based sol-gel process, said process comprising the steps of: a) preparing a dispersion-based sol comprising a transition alumina precursor; b) gelling said sol; c) drying said gelled sol to produce a dry body; and d) calcining said body, wherein substantially all volatile materials are removed, to provide a transition alumina-based body.
Claim 20
Dependent Claim
13 words
The method according to claim 18 wherein said transition alumina precursor is boehmite.
Claim 21
Dependent Claim
65 words
The method according to claim 1 wherein said transition alumina body is prepared by a solution-based sol-gel process, said process comprising the steps of: a) preparing a solution-based sol comprising an transition alumina precursor; b) rigidifying said sol; c) drying said sol to produce a dry body; and d) calcining said body, wherein substantially all volatile materials are removed, to provide a transition alumina-based body.
Claim 22
Dependent Claim
16 words
The method according to claim 20 wherein said transition alumina precursor is a basic aluminum carboxylate.
Claim 23
Dependent Claim
16 words
The method according to claim 20 wherein said transition alumina precursor is a basic aluminum nitrate.
Claim 24
Dependent Claim
19 words
The method according to claim 18 or 20 wherein said dried body is crushed before calcining to produce particles.
Claim 25
Dependent Claim
17 words
The method according to claim 18 or 20 wherein said calcined body is crushed to produce particles.
Claim 26
Dependent Claim
15 words
The method according to claim 1 wherein said calcined-impregnated body is crushed to produce particles.
Claim 27
Dependent Claim
24 words
The method according to claim 1, 18 or 20 wherein said calcining temperature is in the range of about 400° to about 1000° C.
Claim 28
Dependent Claim
15 words
The method according to claim 1, 3, or 7 wherein said calcining atmosphere is air.
Claim 29
Dependent Claim
17 words
The method according to claim 1, 6, or 7 wherein said calcining atmosphere comprises an inert gas.
Claim 30
Dependent Claim
21 words
The method according to claim 1, 6, or 7 wherein said calcining atmosphere comprises an inert gas and a reducing gas.
Claim 31
Dependent Claim
17 words
The method according to claim 1, 6, or 7 wherein said calcining atmosphere comprises a reducing gas.
Claim 32
Dependent Claim
21 words
The method according to claim 1 wherein said sintering temperature is in the range of about 1200° to about 1650° C.
Claim 33
Dependent Claim
21 words
The method according to claim 1 wherein said sintering temperature is in the range of about 1300° to about 1450° C.
Claim 34
Dependent Claim
21 words
The method according to claim 1 wherein said sintering temperature is in the range of about 1350° to about 1450° C.
Claim 35
Dependent Claim
12 words
The method according to claim 7 wherein said sintering atmosphere comprises air.
Claim 36
Dependent Claim
19 words
The method according to claim 5, 6, or 7 wherein said sintering atmosphere comprises air and an inert gas.
Claim 37
Dependent Claim
17 words
The method according to claim 5, 6, or 7 wherein said sintering atmosphere comprises an inert gas.
Claim 38
Dependent Claim
21 words
The method according to claim 5, 6, or 7 wherein said sintering atmosphere comprises an inert gas and a reducing gas.
Claim 39
Dependent Claim
17 words
The method according to claim 5, 6, or 7 wherein said sintering atmosphere comprises a reducing gas.
Claim 40
Dependent Claim
32 words
The method according to claim 1 further comprising step of forming said alumina-based ceramic body as an abrasive grain, a bead, a microsphere, an irregularly shaped particle, a flake, or a microcapsule.
References Cited (Backward Citations)
US3108888A
Cited
US3491492A
Cited
US3491491A
Cited
US3615308A
Cited
US4007020A
Cited
US3734767A
Cited
US3808015A
Cited
US3717497A
Cited
US3853688A
Cited
US4101615A
Cited
US4019914A
Cited
USB502773I5
Cited
US4125406A
Cited
US4217113A
Cited
US4252544A
Cited
US4224099A
Cited
GB2094288A
Cited
GB2099012A
Cited
US4623364A
Cited
US4574003A
Cited
US4744802A
Cited
US4657754A
Cited
US4770671A
Cited
US4615875A
Cited
US4829031A
Cited
EP0291029A1
Cited
US4960441A
Cited
EP0293163A2
Cited
US4881951A
Cited
EP0294208A2
Cited
US4797139A
Cited
WO1990002160A1
Cited
US5011508A
Cited
US4964883A
Cited
US5009676A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-08-18 | 1996-02-17 | 1996-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-08-18 | 2000-02-17 | 2000-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-08-18 | 2004-02-17 | 2004-08-18 | $7700.00 | Window Closed / Lapsed |