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US5236471A
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Process for the production of sintered material based on α-aluminum oxide, especially for abrasives
Assignee: Imerys Fused Minerals Laufenburg GmbH
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Filing: 1992-06-17
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Granted: 1993-08-17
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Expires: 2012-06-17
Abstract
Abstract A sintered material, especially usuable as an abrasive, based on α-aluminum oxide is produced from Al(OH) 3 or aluminum oxide calcined at a lower temperature. Aluminum hydroxide resulting in the Bayer process can be used as the Al(OH) 3 . The sintered material is distinguished by a crystallite size of standard <0.5 μm, high density and great hardness.
Inventors
- 👤 Franciscus Van Dijen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:37
CPC Classifications
C; C01; C01F; C01F7/00; C01F7/02; C01F7/44; C01F7/441; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; C04B35/1115; C09; C09K; C09K3/00; C09K3/14; C09K3/1409; C01P; C01P2002/00; C01P2002/60
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
63 words
A process for the production of sintered materials based on α-aluminum oxide, comprising subjecting aluminum hyroxide [Al(OH) 3 ] or an aluminum oxide which has ben calcined at a lower temperature, either being a precursor of α-aluminum oxide, to grinding and deagglomeration treatment, producing a suspension from the precursor of α-aluminum oxide and optionally additives, drying the suspension, and sintering the dried suspension.
Claim 2
Dependent Claim
63 words
A process for the production of sintered materials based on α-aluminum oxide, comprising subjecting aluminum hyroxide [Al(OH) 3 ] or an aluminum oxide which has ben calcined at a lower temperature, either being a precursor of α-aluminum oxide, to grinding and deagglomeration treatment, producing a suspension from the precursor of α-aluminum oxide and optionally additives, drying the suspension, and sintering the dried suspension.
Claim 3
Dependent Claim
26 words
The process according to claim 1 wherein the grinding and deagglomeration treatment are performed with an attrition mill, a vibratory mill or a stirred ball mill.
Claim 4
Dependent Claim
26 words
The process according to claim 2 wherein the attrition mill, vibratory mill or stirred ball mill is operated with grinding media consisting mainly of α-aluminum oxide.
Claim 5
Dependent Claim
23 words
The process according to claim 3 wherein crystallization seeds of α-aluminum oxide are added to the suspension to prevent grain growth during sintering.
Claim 6
Dependent Claim
22 words
The process according to claim 4 wherein the suspension is adjusted to a pH of less than 5 by adding an acid.
Claim 7
Dependent Claim
29 words
The process according to claim 5 wherein the acid is selected from the group consisting of nitric acid, hydrochloric acid, acetic acid, citric acid, formic acid and oxalic acid.
Claim 8
Dependent Claim
21 words
The process according to claim 6 wherein the suspension is subjected to a vacuum treatment to remove dissolved and/or adsorbed gases.
Claim 9
Dependent Claim
19 words
The process according to claim 7 wherein the sintering is performed at a temperature of 1100° to 1500° C.
Claim 10
Dependent Claim
24 words
The process according to claim 8 wherein aluminum hydroxide resulting in the alumina production by the Bayer process is used as the aluminum hydroxide.
Claim 11
Dependent Claim
55 words
The process according to claim 1 wherein 1 to 5 weight percent, relative to the total weight, calculated as Al 2 O 3 , of crystallization seeds of α-aluminum oxide are added to the suspension to prevent grain growth during sintering, the α-aluminum oxide crystallization seeds having a particle size of less than 1 μm.
Claim 12
Dependent Claim
22 words
The process according to claim 1 wherein the suspension is adjusted to a pH of less than 5 by adding an acid.
Claim 13
Dependent Claim
29 words
The process according to claim 11 wherein the acid is selected from the group consisting of nitric acid, hydrochloric acid, acetic acid, citric acid, formic acid and oxalic acid.
Claim 14
Dependent Claim
21 words
The process according to claim 1 wherein the suspension is subjected to a vacuum treatment to remove dissolved and/or adsorbed gases.
Claim 15
Dependent Claim
19 words
The process according to claim 1 wherein the sintering is performed at a temperature of 1100° to 1500° C.
Claim 16
Dependent Claim
24 words
The process according to claim 1 wherein aluminum hydroxide resulting in the alumina production by the Bayer process is used as the aluminum hydroxide.
Claim 17
Dependent Claim
31 words
A sintered material based on α-aluminum oxide and optionally at least one member selected from the group consisting of carbides, nitrides, and silicides, obtained by the process according to claim 1.
Claim 18
Dependent Claim
75 words
A process for the production of sintered materials based on α-aluminum oxide, comprising subjecting aluminum hydroxide [Al(OH) 3 ] or an aluminum oxide which has been calcined at a lower temperature, either being a precursor of α-aluminum oxide, to grinding and deagglomeration treatment, producing a suspension from the precursor of α-aluminum oxide and optionally additives, adding crystallization seeds of α-aluminum oxide, to prevent grain growth during sintering, drying the suspension, and sintering the dried suspension.
Claim 19
Dependent Claim
75 words
A process for the production of sintered materials based on α-aluminum oxide, comprising subjecting aluminum hydroxide [Al(OH) 3 ] or an aluminum oxide which has been calcined at a lower temperature, either being a precursor of α-aluminum oxide, to grinding and deagglomeration treatment, producing a suspension from the precursor of α-aluminum oxide and optionally additives, adding crystallization seeds of α-aluminum oxide, to prevent grain growth during sintering, drying the suspension, and sintering the dried suspension.
Claim 20
Dependent Claim
97 words
A process for the production of sintered materials based on α-aluminum oxide, consisting of subjecting aluminum hydroxide [Al(OH) 3 ] or an aluminum oxide which has been calcined at a lower temperature, either being a precursor of α-aluminum oxide, to grinding and deagglomeration treatment, producing a suspension from the precursor of α-aluminum oxide and optionally at least one additive from the group consisting of defoamers, sintering auxiliary agents and grain growth inhibitors, obtained by the invention process, adding crystallization seeds of α-aluminum oxide to prevent grain growth during sintering, drying the suspension, and sintering the dried suspension.
Claim 21
Dependent Claim
97 words
A process for the production of sintered materials based on α-aluminum oxide, consisting of subjecting aluminum hydroxide [Al(OH) 3 ] or an aluminum oxide which has been calcined at a lower temperature, either being a precursor of α-aluminum oxide, to grinding and deagglomeration treatment, producing a suspension from the precursor of α-aluminum oxide and optionally at least one additive from the group consisting of defoamers, sintering auxiliary agents and grain growth inhibitors, obtained by the invention process, adding crystallization seeds of α-aluminum oxide to prevent grain growth during sintering, drying the suspension, and sintering the dried suspension.
Claim 22
Dependent Claim
121 words
A process for the production of sintered materials based on α-aluminum oxide, consisting of subjecting aluminum hydroxide [Al(OH) 3 ]]or an aluminum oxide which has been calcined at a lower temperature, either being a precursor of α-aluminum oxide, to grinding and deagglomeration treatment, producing a suspension from the precursor of α-aluminum oxide and optionally at least one additive from the group consisting of defoamers, sintering auxiliary agents and grain growth inhibitors, obtained by the invention process, adding crystallization seeds of α-aluminum oxide to the suspension to prevent grain growth during sintering, drying the suspension, adjusting the suspension to a pH of less than 5 by adding an acid, and sintering the dried suspension at a temperature of 1100° to 1500° C.
Claim 23
Dependent Claim
121 words
A process for the production of sintered materials based on α-aluminum oxide, consisting of subjecting aluminum hydroxide [Al(OH) 3 ]]or an aluminum oxide which has been calcined at a lower temperature, either being a precursor of α-aluminum oxide, to grinding and deagglomeration treatment, producing a suspension from the precursor of α-aluminum oxide and optionally at least one additive from the group consisting of defoamers, sintering auxiliary agents and grain growth inhibitors, obtained by the invention process, adding crystallization seeds of α-aluminum oxide to the suspension to prevent grain growth during sintering, drying the suspension, adjusting the suspension to a pH of less than 5 by adding an acid, and sintering the dried suspension at a temperature of 1100° to 1500° C.
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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) | 1996-08-16 | 1997-02-15 | 1997-08-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-08-16 | 2001-02-15 | 2001-08-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-08-16 | 2005-02-15 | 2005-08-17 | $7700.00 | Window Closed / Lapsed |