Conductivity and Thickness Layer Measurements of Conductive Layers on Conductive Base Materials Using Calibrated Apparent Conductivity Measurements

An eddy current technique for the simultaneous determination of the layer thickness and conductivity of a uniform conductive layer on a conductive base material is presented. The technique uses apparent conductivities measured on the surface of the sample at several frequencies and a calibration-based methodology that compares measured apparent conductivities to a three-dimensional calibration volume. The use of a calibration methodology is advantageous in that it avoids the need for forward or inverse modeling of the layered eddy current problem. Experimental results are presented that support the validity of the technique.

References
  • A.A. Tracton (ed.), Coatings Technology Handbook, 3rd. ed., (2005) CRC Press, Boca Raton, FL.
  • P.M. McIntire and M.L. Mester (eds.), Nondestructive Testing Handbook; Volume Four: Electromagnetic Testing, 2nd. ed. (1986), American Society for Nondestructive Testing, Columbus, OH.
  • S.J. Norton and J.R. Bowler, Theory of eddy current inversion, J. Appl. Phys. 73 (1993), 501-512.
  • J.C. Moulder, E. Uzal and J.H. Rose, Thickness and conductivity of metallic layers from eddy current measurements, Rev. Sci. Instrum. 63 (1992), 3455-3465.
  • C.V. Dodds and W.E. Deeds, Analytical Solutions to Eddy-Current Probe Coil Problems, J. Appl. Phys. 39 (1968), 2829-2838.
  • E. Uzal and J.H. Rose, The impedance of eddy current probes above layered metals whose conductivity and permeability vary continuously, IEEE T. Magn. 29 (1993), 1869-1873.
  • C.C. Cheng, C.V. Dodds and W.E. Deeds, General analysis of probe coils near stratified conductors. Int. J. Nondest. Test. 3 (1971), 109-130.
  • E. Uzal, J.C. Moulder, S. Mitra, and J.H. Rose, Impedance of coils over layered metals with continuously variable conductivity and permeability: Theory and experiment, J. Appl. Phys. 74 (1993), 2076-2089.
  • T.P. Theodoulidis, T.D. Tsiboukis and E.E. Kriezis, Analytical solutions in eddy current testing of layered metals with continuous conductivity profiles, IEEE T. Magn. 31 (1995), 2254-2260.
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