Single-frequency apparent eddy current conductivity assessment of metallic coating thicknesses over nonmagnetic metals

Advantages offered through eddy current technology provide a promising solution to assess metallic coating thicknesses over nonmagnetic metals. Existing single- and multi-frequency impedance-based eddy current techniques are sensitive to both coating/substrate combinations and lift-off deviations fr...

Full description

Saved in:
Bibliographic Details
Published inInternational journal of applied electromagnetics and mechanics Vol. 56; no. 4; pp. 533 - 547
Main Authors Ansari, Zain A., Abu-Nabah, Bassam A., Alkhader, Maen
Format Journal Article
LanguageEnglish
Published Amsterdam IOS Press BV 01.01.2018
Subjects
Approximation
Coating
Computer simulation
Eddy currents
Inspection frequency
Liftoff
Mathematical analysis
Substrates
Online AccessGet full text

Cover

More Information
Summary:Advantages offered through eddy current technology provide a promising solution to assess metallic coating thicknesses over nonmagnetic metals. Existing single- and multi-frequency impedance-based eddy current techniques are sensitive to both coating/substrate combinations and lift-off deviations from those used over the coated calibration blocks. The adoption of apparent eddy current conductivity (AECC) spectroscopy demonstrated the potential benefits to overcome these limitations and deliver one-order of magnitude improvement in coating thickness estimation within a ± 25.4 μm lift-off range. To meet the plane-wave approximation, this technique requires capturing the AECC spectrum over a broad frequency range using a relatively large coil design, which makes the technique less practical. This study takes the AECC-based technology a step further to operate at a single frequency in assessing metallic coating thicknesses of such nonmagnetic-layered structures. The criteria for reducing the coil diameter and selecting the inspection frequency are demonstrated in agreement with the plane-wave approximation and COMSOL simulations. Moreover, a new AECC-based inversion model is developed and validated for single-frequency AECC measurements over different coating thicknesses relevant to the industry.
ISSN:1383-5416
1875-8800
DOI:10.3233/JAE-170037