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Patent US4964883A successfully refreshed from Google Patents.
US4964883A
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Ceramic alumina abrasive grains seeded with iron oxide
Assignee: 3M Co
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Filing: 1988-12-12
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Granted: 1990-10-23
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Expires: 2008-12-12
Abstract
Abstract A process of producing alpha alumina ceramic abrasive grain by sintering alpha alumina monohydrate is improved by seeding with a crystalline oxide of iron having a particle size of less than 150 nm.
Inventors
- 👤 Mary Lou Morris
- 👤 Thomas E. Wood
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:00
CPC Classifications
C; C09; C09K; C09K3/00; C09K3/14; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/1115; C09K3/1409
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
103 words
A process for forming ceramic abrasive grains, comprising the steps of: (a) preparing a dispersion of alpha alumina monohydrate particles; (b) seeding said dispersion with up to about .01 to 10% crystalline iron oxide particles (c) gelling said dispersion; (d) drying the seeded gelled dispersion to form a solid; (e) calcining the solid; (f) crushing the dried or calcined solid to form particles; and (g) sintering the calcined particles, the improvement comprising said crystalline iron oxide particles having an average particle size of less than about 150 nm and said seeding being achieved by adding said crystalline iron oxide particles to said dispersion.
Claim 2
Dependent Claim
103 words
A process for forming ceramic abrasive grains, comprising the steps of: (a) preparing a dispersion of alpha alumina monohydrate particles; (b) seeding said dispersion with up to about .01 to 10% crystalline iron oxide particles (c) gelling said dispersion; (d) drying the seeded gelled dispersion to form a solid; (e) calcining the solid; (f) crushing the dried or calcined solid to form particles; and (g) sintering the calcined particles, the improvement comprising said crystalline iron oxide particles having an average particle size of less than about 150 nm and said seeding being achieved by adding said crystalline iron oxide particles to said dispersion.
Claim 3
Dependent Claim
26 words
The process of claim 1 wherein said crystalline iron oxide particles are selected from the group consisting of goethite, lepidocrocite, hematite, magnetite, maghemite and mixtures thereof.
Claim 4
Dependent Claim
16 words
The process of claim 1 wherein the gel also contains a precursor of a modifying additive.
Claim 5
Dependent Claim
15 words
The process of claim 3 where the modifying additive precursor is a metal containing compound.
Claim 6
Dependent Claim
29 words
The process of claim 4 where said metal is selected from the group consisting of magnesium, zinc, cobalt, nickel, zirconium, hafnium, chromium, yttrium, lanathium, neodynium, titanium and mixtures thereof.
Claim 7
Dependent Claim
16 words
The process of claim 1 wherein said average particle size is from 15 to 100 nm.
Claim 8
Dependent Claim
16 words
The process of claim 1 wherein said average particle size is from 20 to 30 nm.
Claim 9
Dependent Claim
30 words
The process of claim 1 wherein the amount of said iron oxide is from about 0.05% to about 10% by weight based on the weight of the sintered abrasive grains.
Claim 10
Dependent Claim
10 words
Ceramic abrasive grain prepared by the method of claim 1.
Claim 11
Dependent Claim
11 words
The ceramic abrasive grain of claim 7 including a modifying additive.
Claim 12
Dependent Claim
37 words
The ceramic abrasive grain of claim 8 wherein said modifying additive is the oxide of a metal selected from the group consisting of magnesium, zinc, cobalt, nickel, zirconium, hafnium, chromium, yttrium, lanathium, neodynium, titanium and mixtures thereof.
Claim 13
Dependent Claim
20 words
An abrasive article comprising abrasive grain at least a portion of which comprises the ceramic abrasive grain of claim 7.
Claim 14
Dependent Claim
16 words
The abrasive article of claim 12 where said ceramic abrasive grain also includes a modifying additive.
Claim 15
Dependent Claim
16 words
The abrasive article of claim 12 or 13 in the form of a coated abrasive product.
Claim 16
Dependent Claim
16 words
The abrasive article of claim 11 or 12 in the form of a bonded abrasive product.
Claim 17
Dependent Claim
16 words
The abrasive article of claim 11 or 12 in the form of a bonded abrasive wheel.
Claim 18
Dependent Claim
17 words
The abrasive article of claim 11 or 12 in the form of a lofty non-woven abrasive product.
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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) | 1993-10-22 | 1994-04-23 | 1994-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-22 | 1998-04-23 | 1998-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-22 | 2002-04-23 | 2002-10-23 | $7700.00 | Window Closed / Lapsed |