Inspection method using magnetic particles in a liquid carrier in combination with electrical detection means
US4859943A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 28, 1987 |
| Grant date | Aug 22, 1989 |
| Priority date | — |
| Expiry date | Dec 28, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N27/84
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for inspecting the surface of a workpiece for the presence of flaws using a ferrofluid as a penetrant which is applied to the surface of the workpiece and then scanning the surface of the workpiece with electrical detection means placed adjacent to the surface for providing responses indicative of the presence of flaws in the surface of the workpiece. If desired, a magnetic field can be used to induce the flow of the ferrofluid into any flaws prior to inspection, and for post-inspection cleanup as well. By the use of a ferrofluid, the sensitivity of the electrical detection means, advantageously of the eddy current type, is enhanced in typical applications, and also allows the use of an eddy current probe to inspect workpieces made of nonconductive and/or nonferromagnetic materials.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.