Patent US4762655A successfully refreshed from Google Patents.
US4762655A
Expired / Lapsed
US
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Method of sintering translucent alumina
Assignee: Osram Sylvania Inc
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Filing: 1985-11-27
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Granted: 1988-08-09
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Expires: 2005-11-27
Abstract
Abstract An improved process for producing a translucent polycrystalline alumina body comprising sintering a prefired compacted green body of alumina of predetermined shape is disclosed. The green body of alumina includes alumina doped with one or more sintering aids. The method of the present invention comprises sintering the prefired compacted green body of predetermined shape at a maximum sintering temperature in an atmosphere containing nitrogen and an amount of hydrogen greater than or equal to about 2.5 volume percent and less than 75 volume percent for a period of time sufficient to produce a translucent polycrystalline alumina body.
Inventors
- 👤 William H. Rhodes
- 👤 George C. Wei
- 👤 George A. Fryburg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 22:52
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/10; C04B35/111; Y; Y10; Y10S; Y10S264/00; Y10S264/91
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
74 words
A process for producing a translucent polycrystalline alumina body comprising: sintering a prefired, shaped compacted green body at a maximum sintering temperature in an atmosphere containing nitrogen and an amount of hydrogen greater than or equal to about 2.5 volume percent and less than or equal to 35 volume percent for a period of time sufficient to produce a translucent polycrystalline body, said green body comprising alumina doped with one or more sintering aids.
Claim 2
Dependent Claim
74 words
A process for producing a translucent polycrystalline alumina body comprising: sintering a prefired, shaped compacted green body at a maximum sintering temperature in an atmosphere containing nitrogen and an amount of hydrogen greater than or equal to about 2.5 volume percent and less than or equal to 35 volume percent for a period of time sufficient to produce a translucent polycrystalline body, said green body comprising alumina doped with one or more sintering aids.
Claim 3
Dependent Claim
36 words
A process in accordance with claim 1 wherein the atmosphere contains nitrogen and an amount of hydrogen greater than or equal to about 2.5 volume percent and less than or equal to about 18 volume percent.
Claim 4
Dependent Claim
43 words
A process in accordance with claim 1 wherein the sintering aid is selected from the group consisting of MgO, Y 2 O 3 , La 2 O 3 , ZrO 2 , HfO 2 , Yb 2 O 3 , and mixtures thereof.
Claim 5
Dependent Claim
19 words
A process in accordance with claim 1 wherein the maximum sintering temperature is from about 1700° to 2000° C.
Claim 6
Dependent Claim
14 words
A process in accordance with claim 1 wherein the atmosphere is a flowing atmosphere.
Claim 7
Dependent Claim
34 words
A process in accordance with claim 1 wherein the green body is sintered to produce a translucent polycrystalline body having a total transmittance of at least 92% and an in-line transmittance greater than 2%.
Claim 8
Dependent Claim
35 words
A process according to claim 1 wherein the atmosphere contains nitrogen and an amount of hydrogen greater than or equal to about 2.5 volume percent and less than or equal to about 8 volume percent.
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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) | 1991-08-09 | 1992-02-08 | 1992-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-09 | 1996-02-08 | 1996-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-09 | 2000-02-08 | 2000-08-09 | $7700.00 | Window Closed / Lapsed |