US4166831A
Expired / Lapsed
US
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Transparent yttria ceramics and method for producing same
Assignee: Osram Sylvania Inc
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Filing: 1978-03-09
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Granted: 1979-09-04
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Expires: 1998-03-09
Abstract
Abstract An article of manufacture is provided comprising a substantially transparent high density polycrystalline yttria-base body consisting essentially of yttria and from about 0.01 to 5 wt. % alumina. A method for preparing the transparent yttria doped with alumina is also provided comprising admixing alumina or a precursor thereof with yttria or a precursor thereof, drying the admixed powders, calcining the admixed powders and pressing the calcined powders into a desired shape and thereafter sintering the shaped powder for about 1/4 to six hours at a temperature above the eutectic temperature at a sufficiently low oxygen atmosphere to prevent oxidative contaminants.
Inventors
- 👤 William H. Rhodes
- 👤 F. Joseph Reid
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:56
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/50; C04B35/505; H; H01; H01J; H01J5/00; H01J5/02; H01J5/04
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
115 words
A process for preparing a substantially transparent, high density polycrystalline yttria-based body comprising the steps of: admixing alumina or a precursor thereof convertible by sintering to alumina, with yttria or a precursor thereof convertible by sintering to yttria to form a mixture, the alumina or precursor thereof being present in the mixture in an amount to provide between about 0.01 and 5 wt. % alumina upon subsequent sintering; drying the resulting powder; calcining the dried powder at 1000° C. in air; pressing the calcined powder into a given shape; and sintering the shaped powder for about 1/4 to six hours above the eutectic temperature in an atmosphere sufficiently low in oxygen to prevent oxidative contamination.
Claim 2
Dependent Claim
115 words
A process for preparing a substantially transparent, high density polycrystalline yttria-based body comprising the steps of: admixing alumina or a precursor thereof convertible by sintering to alumina, with yttria or a precursor thereof convertible by sintering to yttria to form a mixture, the alumina or precursor thereof being present in the mixture in an amount to provide between about 0.01 and 5 wt. % alumina upon subsequent sintering; drying the resulting powder; calcining the dried powder at 1000° C. in air; pressing the calcined powder into a given shape; and sintering the shaped powder for about 1/4 to six hours above the eutectic temperature in an atmosphere sufficiently low in oxygen to prevent oxidative contamination.
Claim 3
Dependent Claim
20 words
A process as defined in claim 1 wherein the alumina precursors are Al(NO 3 ) 3 or Al(OH) 3 .
Claim 4
Dependent Claim
28 words
A process as defined in claim 1 wherein the yttria precursors are Y 2 (CO 3 ) 3 or Y 2 (C 2 O 4 ) 3 .
Claim 5
Dependent Claim
15 words
A process as defined in claim 1 wherein the powders are dried at 110° C.
Claim 6
Dependent Claim
22 words
A process as defined in claim 1 wherein the dried powder is calcined for about 1 hour at 1000° C. in air.
Claim 7
Dependent Claim
20 words
A process as defined in claim 1 wherein sintering is effected for 1/4 to six hours at about 2100° C.
Claim 8
Dependent Claim
20 words
A process as defined in claim 1 wherein sintering is effected at an oxygen pressure of about 2×10 -10 atmospheres.
Claim 9
Dependent Claim
48 words
A process as defined in claim 1 wherein sintering is effected at an oxygen pressure significantly lower than 10 -10 atmospheres and the resulting black product is thereafter oxidized for about 5 hours at 1500° C. in air to obtain a substantially transparent, high density polycrystalline yttria-based body.
Claim 10
Dependent Claim
134 words
A process for preparing a substantially transparent, high density polycrystalline yttria-based body comprising the steps of: admixing alumina or a precursor thereof convertible by sintering to alumina, with yttria or a precursor thereof convertible by sintering to yttria to form a mixture, the alumina or precursor thereof being present in the mixture in an amount to provide between about 0.01 and 5 wt. % alumina upon subsequent sintering; drying the resulting powder; calcining the dried powder at 1000° C. in air; pressing the calcined powder into a given shape; and sintering the shaped powder for from about 1 to 8 hours below 1920° C., about 1/4 to 6 hours above 1920° C. and about 1 to 2 hours at or about 1925° C. in an atmosphere sufficiently low in oxygen to prevent oxidative contamination.
Claim 11
Dependent Claim
134 words
A process for preparing a substantially transparent, high density polycrystalline yttria-based body comprising the steps of: admixing alumina or a precursor thereof convertible by sintering to alumina, with yttria or a precursor thereof convertible by sintering to yttria to form a mixture, the alumina or precursor thereof being present in the mixture in an amount to provide between about 0.01 and 5 wt. % alumina upon subsequent sintering; drying the resulting powder; calcining the dried powder at 1000° C. in air; pressing the calcined powder into a given shape; and sintering the shaped powder for from about 1 to 8 hours below 1920° C., about 1/4 to 6 hours above 1920° C. and about 1 to 2 hours at or about 1925° C. in an atmosphere sufficiently low in oxygen to prevent oxidative contamination.
Claim 12
Dependent Claim
20 words
A process as defined in claim 9 wherein the alumina precursors are Al(NO 3 ) 3 or Al(OH) 3 .
Claim 13
Dependent Claim
28 words
A process as defined in claim 9 wherein the yttria precursors are Y 2 (CO 3 ) 3 or Y 2 (C 2 O 4 ) 3 .
Claim 14
Dependent Claim
15 words
A process as defined in claim 9 wherein the powders are dried at 110° C.
Claim 15
Dependent Claim
22 words
A process as defined in claim 9 wherein the dried powder is calcined for about 1 hour at 1000° C. in air.
Claim 16
Dependent Claim
61 words
A process as defined in claim 9 wherein sintering is effected for from about 1 to 8 hours at a temperature of from about 1700° C. to 1850° C., for from about 1/4 to six hours at a temperature from about 2000° C. to 2400° C. and then for about 1 to 2 hours at about 1875° C. to 1975° C.
Claim 17
Dependent Claim
53 words
A process as defined in claim 9 wherein sintering is effected below 1920° C. at an oxygen pressure less than or equal to 10 -10 atmospheres, above 1920° C. at an oxygen pressure of about 2×10 -10 atmospheres and at or about 1920° C. at an oxygen pressure of about 1×10 -10 atmospheres.
Claim 18
Dependent Claim
48 words
A process as defined in claim 9 wherein sintering is effected at an oxygen pressure significantly lower than 10 -10 atmospheres and the resulting black product is thereafter oxidized for about 5 hours at 1500° C. in air to obtain a substantially transparent, high density polycrystalline yttria-based body.
References Cited (Backward Citations)
US3545987A
Cited
US3588573A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-09-03 | 1983-03-05 | 1983-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-03 | 1987-03-05 | 1987-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-03 | 1991-03-05 | 1991-09-04 | $7700.00 | Window Closed / Lapsed |