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US3617747A
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Detecting minute amounts of residual core material by means of neutron radiography
Assignee: General Electric Co
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Filing: 1968-09-26
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Granted: 1971-11-02
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Expires: 1988-09-26
Abstract
Abstract A method of detecting very small amounts of residual core material remaining in inaccessible internal passages in a cast metal article is disclosed. Typically, a very small amount of a material having a high neutron absorption cross section, such as gadolinium oxide, is mixed into the core material. After the metal article is cast and the core material removed, such as by dissolving the core away, a neutron radiograph of the article is prepared. Any remaining particles of the doped core material are very distinctly visible in the radiograph. This system is capable of detecting about 0.5 milligram particles.
Inventors
- 👤 Charles D Wilkinson
- 👤 Bruce C Meyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:37
CPC Classifications
G; G01; G01N; G01N23/00; G01N23/02; G01N23/06; G01N23/09; G01N23/18
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
73 words
A process for detecting minute amounts in the order of about 0.5 milligram and larger of residual core material in a cast hollow metal object after removal of the core has been attempted, comprising the step of adding a small amount of a material having a high neutron absorption cross section to said core material before casting so that the presence of residual core material is readily detectable by neutron radiography transmission techniques.
Claim 2
Dependent Claim
73 words
A process for detecting minute amounts in the order of about 0.5 milligram and larger of residual core material in a cast hollow metal object after removal of the core has been attempted, comprising the step of adding a small amount of a material having a high neutron absorption cross section to said core material before casting so that the presence of residual core material is readily detectable by neutron radiography transmission techniques.
Claim 3
Dependent Claim
35 words
The process according to claim 1 wherein from about 0.5 to about 6 weight percent of said material having a high neutron absorption cross section is dispersed throughout said core material before said casting operation.
Claim 4
Dependent Claim
20 words
The process of claim 1 wherein said material having a high neutron absorption cross section is an additive containing gadolinium.
Claim 5
Dependent Claim
24 words
The process according to claim 3 wherein the additive containing gadolinium is present in the core material from about 1 to about 4 percent.
Claim 6
Dependent Claim
37 words
The process according to claim 1 in which the subsequent step of preparing a neutron radiograph is practiced by exposing said cast hollow metal object to a neutron flux of at least about 5 X 104 neutrons/cm.2-sec.
Claim 7
Dependent Claim
33 words
The process according to claim 5 wherein said neutron flux includes primarily thermal neutrons and the ratio of thermal neutrons to gamma radiation is at least about 104 thermal neutrons/milliroentgen of gamma radiation.
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) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |