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US4331627A
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Alumina sintered products and process for their production
Assignee: Niterra Co Ltd
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Filing: 1979-11-27
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Granted: 1982-05-25
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Expires: 1999-11-27
Abstract
Abstract A process for producing an alumina sintered product is disclosed wherein the starting alumina mixture contains about 0.01 to 0.55% by weight of MgO and 0.5 to 5.5% by weight of Y 2 O 3 . The process yields a sintered product having a porosity on the order of less than 0.1% by volume and an average crystal grain size of about 2 microns or less and is particularly suitable for use in high speed microfinish cutting.
Inventors
- 👤 Yoshihiro Yamamoto
- 👤 Kenji Sakurai
- 👤 Hiroshi Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:54
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
83 words
In a process for producing an alumina sintered product by sintering a starting alumina mixture containing sintering assistants using a hot press, the improvement wherein the starting alumina mixture consists essentially of alumina and about 0.01 to 0.55% by weight of MgO and about 1 to 5% by weight of Y 2 O 3 as grain growth inhibitors and the mixture is hot pressed at a temperature of about 1,400° to 1,600° C. and pressure of about 50 to 2,000 kg/cm 2 .
Claim 2
Dependent Claim
83 words
In a process for producing an alumina sintered product by sintering a starting alumina mixture containing sintering assistants using a hot press, the improvement wherein the starting alumina mixture consists essentially of alumina and about 0.01 to 0.55% by weight of MgO and about 1 to 5% by weight of Y 2 O 3 as grain growth inhibitors and the mixture is hot pressed at a temperature of about 1,400° to 1,600° C. and pressure of about 50 to 2,000 kg/cm 2 .
Claim 3
Dependent Claim
17 words
The process of claim 1, wherein the amount of MgO is about 0.02 to 0.5% by weight.
Claim 4
Dependent Claim
32 words
The process of claims 1 or 2, wherein the alumina sintered product has a porosity of about 0.1% by volume or less and an average crystal size of about 2μ or less.
Claim 5
Dependent Claim
56 words
The process of claim 1, wherein the amount of MgO is about 0.02 to 0.5% by weight, the amount of Y 2 O 3 is about 1 to 5% by weight, and the mixture is hot pressed at a temperature of about 1,450° to 1,500° C. at a pressure of 200 to 2,000 kg/cm 2 .
Claim 6
Dependent Claim
15 words
The process of claim 1, wherein said alumina is alpha-alumina of a purity of 99.9%.
Claim 7
Dependent Claim
28 words
The process of claim 1, wherein the alumina sintered product consists essentially of alpha-alumina, Y 3 Al 2 -(AlO 4 ) 3 and MgAl 2 O 4 .
References Cited (Backward Citations)
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US3377176A
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US3905845A
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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) | 1985-05-24 | 1985-11-23 | 1986-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-24 | 1989-11-23 | 1990-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-24 | 1993-11-23 | 1994-05-25 | $7700.00 | Window Closed / Lapsed |