Location

Brunswick, ME

Start Date

1-1-1997 12:00 AM

Description

Eddy currents are used to inspect metals for small near-surface cracks and other defects. The eddy-current signal can be calculated quantitatively, at the cost of some effort, for non-magnetic metals at room temperature. Surprisingly, the same cannot be said for ferromagnetic metals [1]. Neither a quantitative nor a qualitative understanding exists for the change in the impedance when an air-core coil is placed next to an otherwise unspecified ferromagnetic metal. Nickel and iron are the ferromagnetic metals most commonly used in commercial applications. The authors are conducting an experimental/theoretical program aimed at developing a fundamental understanding of the swept-frequency impedance of coils placed next to thick plates of these elements. We start with commercially pure nickel.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

16A

Chapter

Chapter 1: Standard Techniques

Section

Eddy Currents

Pages

249-255

DOI

10.1007/978-1-4615-5947-4_32

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Extreme Sensitivity of Eddy-Currents to the Surface Conditions of Nickel

Brunswick, ME

Eddy currents are used to inspect metals for small near-surface cracks and other defects. The eddy-current signal can be calculated quantitatively, at the cost of some effort, for non-magnetic metals at room temperature. Surprisingly, the same cannot be said for ferromagnetic metals [1]. Neither a quantitative nor a qualitative understanding exists for the change in the impedance when an air-core coil is placed next to an otherwise unspecified ferromagnetic metal. Nickel and iron are the ferromagnetic metals most commonly used in commercial applications. The authors are conducting an experimental/theoretical program aimed at developing a fundamental understanding of the swept-frequency impedance of coils placed next to thick plates of these elements. We start with commercially pure nickel.