US5035724A
Expired / Lapsed
US
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Sol-gel alumina shaped bodies
Assignee: Saint Gobain Abrasives Inc
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Filing: 1990-05-09
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Granted: 1991-07-30
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Expires: 2010-05-09
Abstract
Abstract A process for producing dry substantially crack-free shaped bodies, such as grinding wheels, from a sol-gel alumina hydrate composition is disclosed. The shaped bodies are formed by either a one or a two step forming process and avoid having to pre-prepare alpha alumina grits. The addition of specific crack-avoiding drying control additives, e.g. whiskers, chopped fibers, agarose gels, and formamide, to the sol-gel alumina hydrate prior to water removal therefrom substantially prevents crack-formation during the water removal operation.
Inventors
- 👤 Vimal K. Pukari
- 👤 Norman I. Paille, Jr.
- 👤 Thomas P. Thibaudeau
- 👤 Arup K. Khaund
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:19
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; B; B24; B24D; B24D3/00; B24D3/02; B24D3/34; C04B35/71; C04B35/78; C04B35/80
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
60 words
A method of producing a dry substantially crack-free shaped body from a sol-gel alumina hydrate comprising adding to a sol-gel alumina hydrate prior to the removal of water from the shaped body a drying control additive selected from the group consisting of agarose gel, formamide, and whiskers and chopped fibers of a material which is non-reactive with the alumina hydrate.
Claim 2
Independent Claim
60 words
A method of producing a dry substantially crack-free shaped body from a sol-gel alumina hydrate comprising adding to a sol-gel alumina hydrate prior to the removal of water from the shaped body a drying control additive selected from the group consisting of agarose gel, formamide, and whiskers and chopped fibers of a material which is non-reactive with the alumina hydrate.
Claim 3
Dependent Claim
15 words
The method of claim 1, wherein the drying control additive is whiskers or chopped fibers.
Claim 4
Dependent Claim
25 words
The method of claim 2, wherein the whiskers or chopped fibers are selected from the group consisting of glass, silicon carbide, alumina, alumino-silicate, and zirconia.
Claim 5
Dependent Claim
28 words
The method of claim 2, wherein the whiskers or chopped fibers are present in an amount of from about 2 to 30 volume % of the shaped body.
Claim 6
Dependent Claim
31 words
The method of claim 3, wherein the whiskers have an aspect ratio of from about 5 to 40 and the chopped fibers have an aspect ratio of about 10 to 200.
Claim 7
Dependent Claim
20 words
The method of claim 2, wherein the whiskers or chopped fibers are added to the sol-gel alumina prior to gelation.
Claim 8
Dependent Claim
14 words
The method of claim 1, wherein the drying control additive is an agarose gel.
Claim 9
Dependent Claim
30 words
The method of claim 7, wherein the agarose gel is present in an amount of about 1 to about 3 weight % based on the weight of the alumina hydrate.
Claim 10
Dependent Claim
22 words
The method of claim 7, wherein the agarose gel is an aqueous dispersion of agarose which has been prepared with hot water.
Claim 11
Dependent Claim
12 words
The method of claim 1, wherein the drying control additive is formamide.
Claim 12
Dependent Claim
24 words
The method of claim 10, wherein the formamide is present in an amount of about 10 to 20 weight % of the alumina hydrate.
Claim 13
Dependent Claim
18 words
The method of claim 1, wherein the shaped body is formed in a one-step combined extrusion molding process.
Claim 14
Dependent Claim
23 words
The method of claim 1, wherein the shaped body is formed in a two step process of extrusion followed by molding the extrudates.
Claim 15
Dependent Claim
14 words
The method of claim 1, wherein the shaped body is an abrasive grinding wheel.
Claim 16
Dependent Claim
13 words
The method of claim 1, wherein the alumina hydrate is an alumina monohydrate.
Claim 17
Dependent Claim
26 words
The method of claim 13, wherein the shaped body is fired to convert the alumina hydrate to alpha alumina after the drying has removed the water.
Claim 18
Independent Claim
85 words
A method of forming an alpha-alumina grinding wheel comprising the steps of (1) adding to a sol-gel alumina hydrate a drying control additive selected from the group consisting of agarose gels, formamide, and whiskers and chopped fibers of a material which is non-reactive with the alumina hydrate, (2) forming the sol-gel alumina hydrate gel into the shape of a grinding wheel, (3) removing water from the shape and (4) firing the shape to convert the alumina hydrate into alpha alumina and produce the grinding wheel.
Claim 19
Independent Claim
85 words
A method of forming an alpha-alumina grinding wheel comprising the steps of (1) adding to a sol-gel alumina hydrate a drying control additive selected from the group consisting of agarose gels, formamide, and whiskers and chopped fibers of a material which is non-reactive with the alumina hydrate, (2) forming the sol-gel alumina hydrate gel into the shape of a grinding wheel, (3) removing water from the shape and (4) firing the shape to convert the alumina hydrate into alpha alumina and produce the grinding wheel.
Claim 20
Dependent Claim
18 words
The method of claim 17, wherein the forming is by the direct extrusion of the grinding wheel shape.
Claim 21
Dependent Claim
22 words
The method of claim 17, wherein the forming is by extrusion of shapes which are then molded into the grinding wheel shape.
Claim 22
Dependent Claim
15 words
The method of claim 17, wherein the drying control additive is whiskers or chopped fibers.
Claim 23
Dependent Claim
14 words
The method of claim 17, wherein the drying control additive is an agarose gel.
Claim 24
Dependent Claim
12 words
The method of claim 17, wherein the drying control additive is formamide.
Claim 25
Dependent Claim
56 words
A composition for use in making a dry substantially crack-free alumina hydrate shaped body from which water is removed after formation comprising a sol-gel alumina hydrate, water, and a drying control additive selected from the group consisting of agarose gels, formamide, and whiskers and chopped fibers of a material which is non-reactive with the alumina hydrate.
Claim 26
Dependent Claim
56 words
A composition for use in making a dry substantially crack-free alumina hydrate shaped body from which water is removed after formation comprising a sol-gel alumina hydrate, water, and a drying control additive selected from the group consisting of agarose gels, formamide, and whiskers and chopped fibers of a material which is non-reactive with the alumina hydrate.
Claim 27
Dependent Claim
13 words
The composition of claim 23, wherein the additive is whiskers or chopped fibers.
Claim 28
Dependent Claim
25 words
The composition of claim 24, wherein the whiskers or chopped fibers are selected from the group consisting of glass, silicon carbide, alumina, alumina-silicate and zirconia.
Claim 29
Dependent Claim
12 words
The composition of claim 23, wherein the additive is an agarose gel.
Claim 30
Dependent Claim
10 words
The composition of claim 23, wherein the additive is formamide.
Claim 31
Dependent Claim
13 words
The composition of claim 23, wherein the alumina hydrate is an alumina monohydrate.
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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) | 1994-07-29 | 1995-01-28 | 1995-07-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-07-29 | 1999-01-28 | 1999-07-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-07-29 | 2003-01-28 | 2003-07-30 | $7700.00 | Window Closed / Lapsed |