US3786346A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for detecting defects using magnetic particles in a viscous fluid that restricts their mobility
Assignee: Magnaflux Corp
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Filing: 1973-03-06
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Granted: 1974-01-15
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Expires: 1993-03-06
Abstract
Abstract Method and composition for detecting defects in a magnetizable test piece which involves applying over the surface of the test piece a relatively viscous slurry of ferromagnetic flakes, preferably in an oily medium, the slurry being sufficiently viscous to restrict lateral mobility of the flakes while permitting rotary movement of the flakes, magnetizing the test piece, and thereafter inspecting the test piece to determine the existence of surface flaws denoted by rotation of the flakes due to reorientation thereof by any stray fields present at defects in the test piece.
Inventors
- 👤 D Lorenzi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 10:40
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/83; G01N27/84
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
85 words
The method of detecting defects in a magnetizable test piece which comprises applying over the surface of said test piece a relatively viscous slurry of ferromagnetic flakes, said slurry being sufficiently viscous to restrict lateral mobility and accumulation of the flakes therein while permitting rotary movement of said flakes, magnetizing said test piece, and thereafter inspecting said test piece to determine the existence of flaws denoted by rotation of said flakes due to reorientation thereof by stray fields present at defects in said test piece.
Claim 2
Independent Claim
85 words
The method of detecting defects in a magnetizable test piece which comprises applying over the surface of said test piece a relatively viscous slurry of ferromagnetic flakes, said slurry being sufficiently viscous to restrict lateral mobility and accumulation of the flakes therein while permitting rotary movement of said flakes, magnetizing said test piece, and thereafter inspecting said test piece to determine the existence of flaws denoted by rotation of said flakes due to reorientation thereof by stray fields present at defects in said test piece.
Claim 3
Dependent Claim
23 words
The method of claim 1 in which said slurry includes an oil having a viscosity of from 100 to 500 centistokes at 25*C.
Claim 4
Dependent Claim
13 words
The method of claim 2 in which said oil is a hydrocarbon oil.
Claim 5
Dependent Claim
17 words
The method of claim 1 in which said ferromagnetic flakes are composed of a ferromagnetic stainless steel.
Claim 6
Dependent Claim
38 words
The method of claim 1 in which said slurry contains from 6 to 20 parts by volume of an oil having a viscosity of from 100 to 500 centistokes at 25*C. for every part by volume of flakes.
Claim 7
Dependent Claim
13 words
The method of claim 1 in which said slurry is applied by brushing.
References Cited (Backward Citations)
GB475383A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-01-14 | 1977-07-16 | 1978-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-14 | 1981-07-16 | 1982-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-14 | 1985-07-16 | 1986-01-15 | $7700.00 | Window Closed / Lapsed |