US4147744A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Transparent yttria ceramics and method for producing same
Assignee: Osram Sylvania Inc
•
Filing: 1978-03-31
•
Granted: 1979-04-03
•
Expires: 1998-03-31
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 6 to 14 mole percent lanthana. A method for preparing the transparent yttria doped with lanthana is also provided comprising admixing or co-precipitating lanthana or a precursor thereof with yttria or a precursor thereof, washing, drying and screening the mixture, calcining the admixed or co-precipitated powders, pressing the calcined powders into a desired shape and thereafter sintering the shaped powder for from about 1/6 to 6 hours at a temperature above the H-phase transition and for from about 1/2 to 6 hours at a temperature below the H to C phase transition, said sintering being effected at a sufficiently low oxygen atmosphere to prevent oxidative contaminants.
Inventors
- 👤 William H. Rhodes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:26
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/50; C04B35/505
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
102 words
A process for preparing a substantially transparent, high density polycrystalline yttria-based body comprising admixing lanthana or a precursor thereof convertible by calcining to lanthana-yttria solid solution with yttria or a precursor thereof convertible by calcining to yttria-lanthana solid solution, 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 1/6 to 6 hours at a temperature above the H-phase transition and 1/2to 6 hours at a temperature below the H- to C-phase transition in an atmosphere sufficiently low in oxygen to prevent oxidative contamination.
Claim 2
Dependent Claim
102 words
A process for preparing a substantially transparent, high density polycrystalline yttria-based body comprising admixing lanthana or a precursor thereof convertible by calcining to lanthana-yttria solid solution with yttria or a precursor thereof convertible by calcining to yttria-lanthana solid solution, 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 1/6 to 6 hours at a temperature above the H-phase transition and 1/2to 6 hours at a temperature below the H- to C-phase transition in an atmosphere sufficiently low in oxygen to prevent oxidative contamination.
Claim 3
Dependent Claim
27 words
A process as defined in claim 1 wherein the lanthana and yttria precursors are selected from the group consisting of co-precipitated oxalates, carbonates, hydroxides, and organic carboxylates.
Claim 4
Dependent Claim
24 words
A process as defined in claim 1 wherein the lanthana precursors are selected from the group consisting of oxalates, carbonates, hydroxides, and organic carboxylates.
Claim 5
Dependent Claim
24 words
A process as defined in claim 1 wherein the yttria precursors are selected from the group consisting of oxalates, carbonates, hydroxides, and organic carboxylates.
Claim 6
Dependent Claim
15 words
A process as defined in claim 1 wherein the powders are dried at 110° C.
Claim 7
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 8
Dependent Claim
31 words
A process as defined in claim 1 wherein sintering is effected for 1/6 to 6 hours at about 2150° C. and then for about 1/2 to 6 hours at 1900° C.
Claim 9
Dependent Claim
21 words
A process as defined in claim 1 wherein the sintering is effected at an oxygen pressure of about 10 -10 atmospheres.
Claim 10
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.
References Cited (Backward Citations)
US3792142A
Cited
US3878280A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-04-02 | 1982-10-02 | 1983-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-02 | 1986-10-02 | 1987-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-02 | 1990-10-02 | 1991-04-03 | $7700.00 | Window Closed / Lapsed |