Material Characterization by Electrical Conductivity Assessment Using Impedance Analysis

Eddy currents non destructive testing is a well known method for material characterization, which is sensitive to different properties of conductive materials, such as: electrical conductivity, magnetic permeability, phase proportions, hardness, size, discontinuities, etc. These properties alter the flow of the currents induced in the sample under test by an AC magnetic field. One of the most common applications of the method is the evaluation of electrical conductivity, by a procedure that requires at least two reference standards, and is not valid for very thin samples (less than 1 mm, roughly). In this paper a variation of that procedure is proposed, in which only one reference standard is needed. The procedure allows for the evaluation of conductivities in the range 0.9 - 59 MS/m on planar samples with thickness greater than 30 μm.