US5219806A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alpha phase seeding of transition alumina using chromium oxide-based nucleating agents
Assignee: 3M Co
•
Filing: 1990-07-16
•
Granted: 1993-06-15
•
Expires: 2010-07-16
Abstract
Abstract This invention provides an improved alpha alumina-based ceramic and a method to make the same. The improvement consists of the addition of a chromium-based nucleating agent. Particularly useful embodiments of the improved alpha alumina-based ceramic include abrasive particles and fibers.
Inventors
- 👤 Thomas E. Wood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:52
CPC Classifications
C; C09; C09K; C09K3/00; C09K3/14; C09K3/1409; C09K3/1418; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/1115; C04B35/622; C04B35/62227; C04B35/62231
Claims Analysis
Total Claims: 50
Claim 1
Independent Claim
16 words
Alpha alumina-based ceramic having a seeded microstructure comprising alpha alumina domains nucleated with alpha chromic oxide.
Claim 2
Dependent Claim
16 words
Alpha alumina-based ceramic having a seeded microstructure comprising alpha alumina domains nucleated with alpha chromic oxide.
Claim 3
Dependent Claim
14 words
The alpha alumina-based ceramic according to claim 1, said ceramic having a well-seeded microstructure.
Claim 4
Dependent Claim
13 words
The alpha alumina-based ceramic according to claim 1 also including a modifying additive.
Claim 5
Dependent Claim
16 words
The alpha alumina-based ceramic according to claim 2 wherein said modifying additive is a metal-containing compound.
Claim 6
Dependent Claim
21 words
The alpha alumina-based ceramic according to claim 1 consisting essentially of said alpha alumina and chromium oxide nucleating material dispersed therein.
Claim 7
Dependent Claim
34 words
The alpha alumina-based ceramic according to claim 1 having a content of chromium derived from said alpha chromic oxide of about 0.085 to about 7 weight percent, based on the amount of alumina present.
Claim 8
Dependent Claim
35 words
The alpha alumina-based ceramic according to claim 1 having a content of chromium derived from said alpha chromic oxide of about 0.3 to about 3.5 weight percent, based on the amount of alpha alumina present.
Claim 9
Dependent Claim
28 words
The alpha alumina-based ceramic according to claim 1 wherein the total amount of alumina plus chromia is at least 60 weight percent, based on the total ceramic composition.
Claim 10
Dependent Claim
28 words
The alpha alumina-based ceramic according to claim 1 wherein the total amount of alumina plus chromia is at least 90 weight percent, based on the total ceramic composition.
Claim 11
Dependent Claim
8 words
Abrasive grain comprising the ceramic of claim 1.
Claim 12
Dependent Claim
20 words
An abrasive article comprising abrasive grain at least a portion of which comprises said abrasive grain according to claim 10.
Claim 13
Dependent Claim
15 words
The abrasive article according to claim 11 in the form of a coated abrasive product.
Claim 14
Dependent Claim
15 words
The abrasive article according to claim 11 in the form of a bonded abrasive product.
Claim 15
Dependent Claim
16 words
The bonded abrasive article according to claim 13 in the form of a bonded abrasive wheel.
Claim 16
Dependent Claim
18 words
The abrasive article according to claim 11 in the form of a low density, three-dimensional non-woven abrasive product.
Claim 17
Dependent Claim
8 words
A fiber comprising the ceramic of claim 1.
Claim 18
Dependent Claim
24 words
The fiber according to claim 16 having less than 0.1 weight percent iron equivalence, based on the total alpha alumina content of said ceramic.
Claim 19
Dependent Claim
24 words
The fiber according to claim 16 having less than 0.05 weight percent iron equivalence, based on the total alpha alumina content of said ceramic.
Claim 20
Dependent Claim
16 words
The fiber according to claim 16 having an average surface roughness height less than 0.100 micrometer.
Claim 21
Dependent Claim
33 words
The alpha alumina-based ceramic according to claim 1 wherein said ceramic is a shape selected from a fiber, a bead, a microsphere, a flake, an irregularly shaped particle, a film, or a microcapsule.
Claim 22
Independent Claim
145 words
A method of making an alpha alumina-based ceramic, said method comprising the steps of: a) preparing an aqueous mixture comprising: i) an alpha alumina precursor; and ii) a sufficient amount to nucleate during the following process steps said alpha alumina precursor to alpha alumina having a seeded microstructure of at least one chromium compound selected from the group consisting of an alpha chromic oxide precursor, alpha chromic oxide, and mixtures thereof; b) immobilizing said aqueous mixture; c) drying said immobilized aqueous mixture to produce a dry body; d) calcining said body at a temperature and in an atmosphere sufficient to provide substantially all the chromium derived from said chromium compound within said body in an oxidation state of not greater than +3; and e) sintering said calcined body at a temperature and in an atmosphere sufficient to provide alpha alumina-based ceramic having a seeded microstructure.
Claim 23
Independent Claim
145 words
A method of making an alpha alumina-based ceramic, said method comprising the steps of: a) preparing an aqueous mixture comprising: i) an alpha alumina precursor; and ii) a sufficient amount to nucleate during the following process steps said alpha alumina precursor to alpha alumina having a seeded microstructure of at least one chromium compound selected from the group consisting of an alpha chromic oxide precursor, alpha chromic oxide, and mixtures thereof; b) immobilizing said aqueous mixture; c) drying said immobilized aqueous mixture to produce a dry body; d) calcining said body at a temperature and in an atmosphere sufficient to provide substantially all the chromium derived from said chromium compound within said body in an oxidation state of not greater than +3; and e) sintering said calcined body at a temperature and in an atmosphere sufficient to provide alpha alumina-based ceramic having a seeded microstructure.
Claim 24
Dependent Claim
28 words
The method according to claim 21 wherein said chromium compound particles of step (a) have an average particle size of less than 0.5 micrometers in the primary dimension.
Claim 25
Dependent Claim
14 words
The method according to claim 22, said alpha alumina-based ceramic having a well-seeded microstructure.
Claim 26
Dependent Claim
21 words
The method according to claim 22 wherein said aqueous mixture is a dispersion and said immobilizing is by gelling said dispersion.
Claim 27
Dependent Claim
21 words
The method according to claim 22 wherein said aqueous mixture is a solution and said immobilizing is by rigidifying said solution.
Claim 28
Dependent Claim
19 words
The method according to claim 22 wherein at least one of said calcining atmosphere or sintering atmosphere comprises air.
Claim 29
Dependent Claim
26 words
The method according to claim 22 wherein at least one of said calcining atmosphere or sintering atmosphere comprises a mixture of air and an inert gas.
Claim 30
Dependent Claim
21 words
The method according to claim 22 wherein at least one of said calcining atmosphere or sintering atmosphere comprises an inert gas.
Claim 31
Dependent Claim
28 words
The method according to claim 22 wherein at least one of said calcining atmosphere or sintering atmosphere comprises a mixture of an inert gas and a reducing gas.
Claim 32
Dependent Claim
21 words
The method according to claim 22 wherein at least one of said calcining atmosphere or sintering atmosphere comprises a reducing gas.
Claim 33
Dependent Claim
31 words
The method according to claim 22 wherein said alpha chromic oxide precursor is a compound selected from the group consisting of CrO 2 , HCrO 2 , and a mixture thereof.
Claim 34
Dependent Claim
13 words
The method according to claim 24 wherein said alpha alumina precursor is boehmite.
Claim 35
Dependent Claim
16 words
The method according to claim 25 wherein said alpha alumina precursor is a basic aluminum carboxylate.
Claim 36
Dependent Claim
16 words
The method according to claim 25 wherein said alpha alumina precursor is a basic aluminum nitrate.
Claim 37
Dependent Claim
17 words
The method according to claim 22 wherein said dried body is crushed before calcining to produce particles.
Claim 38
Dependent Claim
15 words
The method according to claim 22 wherein said calcined body is crushed to produce particles.
Claim 39
Dependent Claim
41 words
The method according to claim 22 wherein the amount of said compound added to said aqueous mixture is sufficient to provide about 0.085 to about 7 weight percent chromium, based on the amount of alumina present in said alpha alumina-based ceramic.
Claim 40
Dependent Claim
41 words
The method according to claim 22 wherein the amount of said compound added to said aqueous mixture is sufficient to provide about 0.3 to about 3.5 weight percent chromium, based on the amount of alumina present in said alpha alumina-based ceramic.
Claim 41
Dependent Claim
20 words
The method according to claim 22 wherein said calcining temperature is in the range of about 450° to 1000° C.
Claim 42
Dependent Claim
25 words
The method according to claim 22 wherein said calcined body is sintered at a temperature in the range of about 1200° to about 1650° C.
Claim 43
Dependent Claim
25 words
The method according to claim 22 wherein said calcined body is sintered at a temperature in the range of about 1300° to about 1450° C.
Claim 44
Dependent Claim
25 words
The method according to claim 22 wherein said calcined body is sintered at a temperature in the range of about 1350° to about 1450° C.
Claim 45
Dependent Claim
34 words
The method according to claim 22 wherein said immobilized aqueous solution is formed as an abrasive grain, a fiber, a bead, a microsphere, an irregularly shaped particle, a flake, a film, or a microcapsule.
Claim 46
Dependent Claim
29 words
The method according to claim 21 wherein said chromium compound particles of step (a) has an average particle size of less than about 0.25 micrometer in the primary dimension.
Claim 47
Dependent Claim
29 words
The method according to claim 21 wherein said chromium compound particles of step (a) has an average particle size of less than about 0.1 micrometer in the primary dimension.
Claim 48
Dependent Claim
50 words
The method according to claim 21 wherein said chromium compound of step (a) is in the form of particles each having a surface and having chromium present at said surface, wherein at least some of said chromium at said surface of said particles has an oxidation state greater than +3.
Claim 49
Dependent Claim
12 words
The method according to claim 22 wherein said calcining atmosphere is reducing.
Claim 50
Dependent Claim
34 words
The method according to claim 22 wherein said sintering atmosphere of step (e) is sufficient to provide chromium in said chromium compound in an oxidation state during said sintering step of up to +3.
References Cited (Backward Citations)
US3108888A
Cited
US3491492A
Cited
US3491491A
Cited
US3615308A
Cited
US4007020A
Cited
US3808015A
Cited
US3717497A
Cited
US3853688A
Cited
US4101615A
Cited
US4019914A
Cited
USB502773I5
Cited
US4125406A
Cited
US4217113A
Cited
US4252544A
Cited
GB2094288A
Cited
GB2099012A
Cited
US4623364A
Cited
US4574003A
Cited
US4744802A
Cited
US4657754A
Cited
US4770671A
Cited
US4829031A
Cited
EP0291029A1
Cited
EP0293163A2
Cited
US4881951A
Cited
EP0294208A2
Cited
US4797139A
Cited
WO1990002160A1
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) | 1996-06-14 | 1996-12-14 | 1997-06-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-06-14 | 2000-12-14 | 2001-06-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-06-14 | 2004-12-14 | 2005-06-15 | $7700.00 | Window Closed / Lapsed |