Patent US4141781A successfully refreshed from Google Patents.
US4141781A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for rapid removal of cores made of βAl2 O3 from directionally solidified eutectic and superalloy and superalloy materials
Assignee: General Electric Co
•
Filing: 1977-10-06
•
Granted: 1979-02-27
•
Expires: 1997-10-06
Abstract
Abstract Caustic solutions are employed in an autoclave process to rapidly remove cores made of β-Al 2 O 3 from directionally solidified eutectic alloy and superalloy materials.
Inventors
- 👤 Charles D. Greskovich
- 👤 Marcus P. Borom
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:26
CPC Classifications
B; B22; B22D; B22D29/00; B22D29/001; B22D29/002
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
119 words
A method for removing a core of β-alumina material from a casting comprising the process steps of: (a) placing the casting containing the core of ceramic material in an autoclave including an aqueous leaching solution containing a material which is one selected from the group consisting of NaOH and KOH; (b) heating the casting, ceramic material and leaching solution to a temperature of at least about 200° C.; (c) dissolving substantially all of an interconnecting network of ceramic material formed in situ between grains of the material by sintering by chemical attack caused by the leaching solution, and (d) removing at least some of the undissolved ceramic material from the casting by the solution agitated by the chemical reaction.
Claim 2
Independent Claim
119 words
A method for removing a core of β-alumina material from a casting comprising the process steps of: (a) placing the casting containing the core of ceramic material in an autoclave including an aqueous leaching solution containing a material which is one selected from the group consisting of NaOH and KOH; (b) heating the casting, ceramic material and leaching solution to a temperature of at least about 200° C.; (c) dissolving substantially all of an interconnecting network of ceramic material formed in situ between grains of the material by sintering by chemical attack caused by the leaching solution, and (d) removing at least some of the undissolved ceramic material from the casting by the solution agitated by the chemical reaction.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein the temperature in the autoclave is no greater than about 350° C.
Claim 4
Dependent Claim
31 words
The method of claim 1 wherein the composition of the aqueous leaching solution is from about 10 percent by weight to about 70 percent by weight hydroxide and the balance water.
Claim 5
Dependent Claim
10 words
The method of claim 3 wherein the hydroxide is KOH.
Claim 6
Dependent Claim
15 words
The method of claim 2 wherein the temperature in the autoclave is about 290° C.
Claim 7
Dependent Claim
31 words
The method of claim 5 wherein the composition of the aqueous leaching solution is from about 10 percent by weight to about 70 percent by weight hydroxide and the balance water.
Claim 8
Dependent Claim
10 words
The method of claim 6 wherein the hydroxide is KOH.
References Cited (Backward Citations)
US2989385A
Cited
US3859427A
Cited
US4068048A
Cited
US4013477A
Cited
US4052538A
Cited
US4073662A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-02-26 | 1982-08-28 | 1983-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-02-26 | 1986-08-28 | 1987-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-02-26 | 1990-08-28 | 1991-02-27 | $7700.00 | Window Closed / Lapsed |