Patent US4031945A successfully refreshed from Google Patents.
US4031945A
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Process for making ceramic molds having a metal oxide barrier for casting and directional solidification of superalloys
Assignee: General Electric Co
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Filing: 1976-04-07
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Granted: 1977-06-28
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Expires: 1996-04-07
Abstract
Abstract At least one element of a superalloy cast into a refractory oxide-silica investment mold is oxidized to form a metal oxide barrier layer at the mold-metal interface to permit directional solidification of the cast superalloy at elevated temperatures without metal-mold reaction.
Inventors
- 👤 Michael F. X. Gigliotti, Jr.
- 👤 Charles D. Greskovich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 06:35
CPC Classifications
B; B22; B22C; B22C9/00; B22C9/02; B22C9/04; B22D; B22D21/00; B22D21/06
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
210 words
A method for forming a barrier layer at the mold-metal interface in a mold suitable for the casting and directional solidification of superalloys therein including the process steps of: placing a mold made of a material comprising a first refractory oxide bonded together by silica within a furnace; introducing a controlled prevailing atmosphere into the furnace; heating the mold in the controlled prevailing atmosphere at an elevated temperature for a sufficient period of time to dissolve some of the first refractory oxide into the silica; casting a melt of superalloy metal into a cavity of the mold, and forming a barrier layer comprising a second refractory oxide by the oxidation of at least one constituent of the superalloy within the mold in integral contact with the first refractory oxide material, the barrier layer having a surface defining at least a portion of the interior wall surfaces of the cavity into which the superalloy melt is cast and comes into contact therewith, and having a thickness greater than 1 micron to substantially prevent the molten metal from penetrating into the mold structure and the microstructure of the mold in the vicinity of the cavity exhibiting a substantially porous free structure containing silica bearing phases therein in contact with the barrier layer.
Claim 2
Independent Claim
210 words
A method for forming a barrier layer at the mold-metal interface in a mold suitable for the casting and directional solidification of superalloys therein including the process steps of: placing a mold made of a material comprising a first refractory oxide bonded together by silica within a furnace; introducing a controlled prevailing atmosphere into the furnace; heating the mold in the controlled prevailing atmosphere at an elevated temperature for a sufficient period of time to dissolve some of the first refractory oxide into the silica; casting a melt of superalloy metal into a cavity of the mold, and forming a barrier layer comprising a second refractory oxide by the oxidation of at least one constituent of the superalloy within the mold in integral contact with the first refractory oxide material, the barrier layer having a surface defining at least a portion of the interior wall surfaces of the cavity into which the superalloy melt is cast and comes into contact therewith, and having a thickness greater than 1 micron to substantially prevent the molten metal from penetrating into the mold structure and the microstructure of the mold in the vicinity of the cavity exhibiting a substantially porous free structure containing silica bearing phases therein in contact with the barrier layer.
Claim 3
Dependent Claim
19 words
The method of claim 1 wherein the thickness of the barrier layer so formed is at least 10 microns.
Claim 4
Dependent Claim
39 words
The method of claim 1 wherein the first refractory oxide is one selected from the group consisting of aluminum oxide, calcium oxide, yttrium oxide and magnesium oxide, and the composition of the superalloy material is substantially free of aluminum.
Claim 5
Dependent Claim
22 words
The method of claim 3 wherein the composition of the mold is from approximately 80.0% to about 99.9% by weight aluminum oxide.
Claim 6
Dependent Claim
16 words
The method of claim 1 wherein the first and second refractory oxides are the same material.
Claim 7
Dependent Claim
28 words
The method of claim 5 wherein the first refractory oxide is one selected from the group consisting of an aluminum oxide, yttrium oxide, calcium oxide and magnesium oxide.
Claim 8
Dependent Claim
20 words
The method of claim 6 wherein the thickness of the barrier layer so formed is greater than about 1 micron.
Claim 9
Dependent Claim
19 words
The method of claim 7 wherein the thickness of the barrier layer so formed is greater than 10 microns.
Claim 10
Dependent Claim
27 words
The method of claim 1 wherein the second refractory oxide comprises material derived in part from the melt of metal cast into the cavity of the mold.
Claim 11
Dependent Claim
35 words
The method of claim 3 wherein the second refractory oxide comprises oxide constituents from the superalloy metal melt of at least one metal selected from the group consisting of magnesium, yttrium, hafnium, zirconium, and titanium.
Claim 12
Dependent Claim
32 words
The method of claim 9 wherein the second refractory oxide comprises oxide constituents from the superalloy metal melt and at least one metal selected from the group consisting of magnesium and yttrium.
Claim 13
Dependent Claim
25 words
The method of claim 2 wherein the first refractory oxide is one selected from the group consisting of aluminum oxide, yttrium oxide and magnesium oxide.
Claim 14
Dependent Claim
26 words
The method of claim 2 wherein the supplied prevailing atmosphere comprises a mixture of an inert carrier gas and a predetermined amount of an oxygen-bearing gas.
Claim 15
Dependent Claim
11 words
The method of claim 13 wherein the inert gas is argon.
Claim 16
Dependent Claim
21 words
The method of claim 13 wherein the supplied prevailing atmosphere is provided by introducing pure oxygen into the inert carrier gas.
Claim 17
Dependent Claim
16 words
The method of claim 15 wherein oxygen comprises from 0.01% to 5% of the gas mixture.
Claim 18
Dependent Claim
11 words
The method of claim 15 wherein the inert gas is argon.
Claim 19
Dependent Claim
20 words
The method of claim 13 wherein the prevailing atmosphere is provided by introducing water vapor into the inert carrier gas.
Claim 20
Dependent Claim
13 words
The method of claim 13 wherein the oxygen bearing gas is carbon monoxide.
Claim 21
Dependent Claim
51 words
The method of claim 19 including practicing the process step of heating the mold in the furnace with a graphite susceptor, and forming carbon monoxide to mix in the inert carrier gas by reacting the graphite of the susceptor with the oxygen-bearing gas in the prevailing atmosphere introduced into the furnace.
Claim 22
Dependent Claim
71 words
The method of claim 19 including practicing the process step prior to heating the mold to an elevated temperature of disposing a body of carbon-bearing material within the confines of the furnace, and practicing the process step subsequent to heating the mold to an elevated temperature, forming carbon monoxide in the inert carrier gas by reacting the carbon-bearing material with the oxygen-bearing gas in the prevailing atmosphere introduced into the furnace.
Claim 23
Dependent Claim
12 words
The method of claim 18 wherein the oxygen-bearing gas is carbon monoxide.
Claim 24
Dependent Claim
29 words
The method of claim 2 wherein the prevailing atmosphere is a gas selected from the group consisting of hydrogen and hydrogen containing a predetermined amount of water vapor therein.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-06-27 | 1980-12-27 | 1981-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-06-27 | 1984-12-27 | 1985-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-06-27 | 1988-12-27 | 1989-06-28 | $7700.00 | Window Closed / Lapsed |