Patent US4247333A successfully refreshed from Google Patents.
US4247333A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alumina shell molds used for investment casting in directional solidification of eutectic superalloys
Assignee: General Electric Co
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Filing: 1979-12-26
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Granted: 1981-01-27
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Expires: 1999-12-26
Abstract
Abstract An alumina investment casting mold has a microstructure characterized by the porous nature of the interconnecting alumina grains which is indicative of alumina-silica molds fired in a reducing atmosphere to remove the silica.
Inventors
- 👤 Glenn W. Ledder
- 👤 Wayne D. Pasco
- 👤 Paul S. Svec
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:46
CPC Classifications
B; B22; B22C; B22C9/00; C; C30; C30B; C30B21/00; C30B21/02
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
54 words
An alumina shell mold formed in situ by firing a silica-bonded alumina shell mold in a controlled atmosphere of dry hydrogen gas having a dewpoint of less than 35° F. at a temperature of at least 1700° C. wherein said mold has a microstructure characterized by the porous nature of the interconnecting alumina grains.
Claim 2
Dependent Claim
54 words
An alumina shell mold formed in situ by firing a silica-bonded alumina shell mold in a controlled atmosphere of dry hydrogen gas having a dewpoint of less than 35° F. at a temperature of at least 1700° C. wherein said mold has a microstructure characterized by the porous nature of the interconnecting alumina grains.
References Cited (Backward Citations)
US4131475A
Cited
US4187266A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-27 | 1984-07-28 | 1985-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-27 | 1988-07-28 | 1989-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-27 | 1992-07-28 | 1993-01-27 | $7700.00 | Window Closed / Lapsed |