Patent US3701379A successfully refreshed from Google Patents.
US3701379A
Expired / Lapsed
US
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Process of casting utilizing magnesium oxide cores
Assignee: RTX Corp
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Filing: 1971-07-06
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Granted: 1972-10-31
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Expires: 1991-07-06
Abstract
Abstract A metal casting having internal passages and apertures can be formed by pouring molten metal into a mold having a magnesium oxide core disposed therein. The core can be made by forming a mixture of magnesium oxide and an evanescent resin and shaping this mixture by suitable molding techniques. The evanescent resin is then slowly volatilized to leave a core of substantially pure MgO which can be sintered to form a carbonaceous material-free, self-supporting body. After a casting is made around the core, it can be removed by washing the casting in a non-corrosive media such as water or dilute acetic acid.
Inventors
- 👤 Michael H Fassler
- 👤 Norman E Brinker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 08:35
CPC Classifications
B; B22; B22D; B22D29/00; B22D29/001; B22D29/002; B22C; B22C9/00; B22C9/10; B22C9/101; B22C9/106
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
74 words
The process according to claim 1 wherein said heating is divided into two stages, the first stage including slowly heating said body at a rate sufficient to volatilize substantially all of the carbonaceous material but insufficient to generate quantities of gases which would dislodge particles of said magnesium oxide, the second stage including heating the body sufficiently to sinter the magnesium oxide particles together and form a core, but insufficient to cause appreciable shrinkage.
Claim 2
Dependent Claim
21 words
The process according to claim 1 wherein the magnesium oxide has a particle size between about 25 to 150 Mu .
Claim 3
Dependent Claim
38 words
The process according to claim 1 wherein said mixture is prepared by dissolving said resin in an organic solvent and said magnesium oxide is slurried in the solution, said solvent then being volatilized to produce a putty-like mass.
Claim 4
Dependent Claim
50 words
The process according to claim 4 wherein at least a portion of the putty-like mass is placed in a transfer cavity of a transfer molding press and subjected to pressure in the order of 10,000 to 20,000 p.s.i. to force the mass into an associated die having said predetermined shape.
Claim 5
Dependent Claim
22 words
The process according to claim 4 wherein said mixture further includes stearic acid as a lubricant and lithium fluoride as a flux.
Claim 6
Dependent Claim
11 words
The process according to claim 4 wherein said resin is polystyrene.
Claim 7
Dependent Claim
18 words
The process according to claim 1 wherein the dissolving step involves contacting said core with an organic acid.
Claim 8
Dependent Claim
11 words
The process according to claim 8 wherein the acid is acetic.
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) | 1975-10-31 | 1976-05-01 | 1976-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-31 | 1980-05-01 | 1980-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-31 | 1984-05-01 | 1984-10-31 | $7700.00 | Window Closed / Lapsed |