US3957104A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making an apertured casting
Assignee: National Aeronautics and Space Administration
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Filing: 1974-02-27
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Granted: 1976-05-18
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Expires: 1994-02-27
Abstract
Abstract An apertured casting is made by first forming a duplicate in the shape of the finished casting, positioning refractory metal bodies such as wires in the duplicate at points corresponding to apertures or passageways in finished products, forming a ceramic coating on the duplicate, removing the duplicate material, firing the ceramic in a vacuum or inert atmosphere, vacuum casting the metal in the ceramic form, removing the ceramic form, heating the cast object in an atmospheric furnace to oxidize the refractory metal bodies and then leaching the oxidized refractory bodies from the casting with a molten caustic agent or acid solution.
Inventors
- 👤 Andrew Terpay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:28
CPC Classifications
B; B22; B22D; B22D29/00; B22D29/001; B22D29/002; B22C; B22C9/00; B22C9/02; B22C9/04; F; F05; F05B; F05B2220/00; F05B2220/30; F05B2220/302; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49316; Y10T29/49336; Y10T29/49339; Y10T29/49341
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
187 words
A method of making a cast object of the type having perforations or passages therein comprising the steps of: forming a duplicate of the object to be cast from a material having a relatively low melting point; inserting wires in said object duplicate corresponding to the desired location of apertures in said object, said wires being selected from a metal which oxidizes when subjected to a temperature from about 1000° to 2000°; forming a ceramic coating on said duplicate object; removing said material; firing said ceramic in a substantially nonoxidizing atmosphere to produce a mold and to form an oxide coating on said wires; casting a metal in said ceramic mold; removing said ceramic mold; heating said cast object to a temperature range of from about 1000° F to 2000° in an oxidizing atmosphere to oxidize said wires; and leaching out the oxidized wires with an agent which corrodes and dissolves the oxidized wires without reacting significantly with the casting metal at a temperature of from about 1000° F to 1500° F, the melting point of said material being lower than the oxidation temperature of said wires.
Claim 2
Independent Claim
187 words
A method of making a cast object of the type having perforations or passages therein comprising the steps of: forming a duplicate of the object to be cast from a material having a relatively low melting point; inserting wires in said object duplicate corresponding to the desired location of apertures in said object, said wires being selected from a metal which oxidizes when subjected to a temperature from about 1000° to 2000°; forming a ceramic coating on said duplicate object; removing said material; firing said ceramic in a substantially nonoxidizing atmosphere to produce a mold and to form an oxide coating on said wires; casting a metal in said ceramic mold; removing said ceramic mold; heating said cast object to a temperature range of from about 1000° F to 2000° in an oxidizing atmosphere to oxidize said wires; and leaching out the oxidized wires with an agent which corrodes and dissolves the oxidized wires without reacting significantly with the casting metal at a temperature of from about 1000° F to 1500° F, the melting point of said material being lower than the oxidation temperature of said wires.
Claim 3
Dependent Claim
21 words
The method of claim 1 wherein said wires are selected from the group of metals consisting of molybdenum, tantalum and tungsten.
Claim 4
Dependent Claim
34 words
The method of claim 1 wherein the leaching agent is a molten caustic salt selected from the group consisting of Na 2 CO 3 , K 2 CO 3 , NaFl, CaFl and NaOH.
Claim 5
Dependent Claim
21 words
The method of claim 1 wherein the agent is an acid comprising at least 35% nitric acid, the remainder being water.
Claim 6
Dependent Claim
16 words
The method of claim 4 wherein some of the water is replaced by 20% hydrofluoric acid.
Claim 7
Dependent Claim
24 words
The method of claim 1 wherein said wires are positioned to extend at least 0.030 inch out of the surface of said duplicate object.
Claim 8
Dependent Claim
21 words
The method of claim 1 wherein said casting metal is one selected from the group consisting of high temperature-chrome nickel alloys.
Claim 9
Dependent Claim
19 words
The method of claim 1 wherein said wires range from about 0.003 inch to about 0.125 inch in diameter.
Claim 10
Dependent Claim
15 words
The method of claim 1 wherein said wires are tungsten and said agent is NaFl.
Claim 11
Dependent Claim
28 words
The method of claim 1 wherein said wires are tantalum and said agent is a mixture comprising 40% nitric acid and 20% hydrofluoric acid, the remainder being water.
Claim 12
Dependent Claim
23 words
The method of claim 1 wherein the ceramic firing step is carried out in a vacuum of less than about 50 microns pressure.
Claim 13
Dependent Claim
25 words
The method of claim 1 wherein the ceramic firing step is carried out in a hydrogen atmosphere of about 2 ounces per square inch pressure.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-05-18 | 1979-11-17 | 1980-05-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-18 | 1983-11-17 | 1984-05-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-18 | 1987-11-17 | 1988-05-18 | $7700.00 | Window Closed / Lapsed |