A ferrite-cored funnel-shaped probe for pulse-modulation eddy current screening of pitting corrosion in conductive heterostructures

The hostile and corrosive environments may leave the conductive heterostructures vulnerable to the pitting corrosion which undermines the structural integrity and safety. It is imperative to non-intrusively detect and evaluate the pitting corrosion with high detection depth and spatial resolution via non-destructive evaluation (NDE) methods before it progresses further. In light of this, following the investigation of pulse-modulation eddy current (PMEC) testing, in this paper a ferrite-cored funnel-shaped probe is proposed for quantitative screening of the pitting corrosion in conductive heterostructures. Closed-form expressions of field quantities are formulated via the semi-analytical modelling for theoretical simulations. The simulation results reveal the better characteristics of the probe particularly in terms of high-sensitivity testing and capability of balancing the eddy current penetration depth and planar concentration. In parallel, experiments have been carried out to further investigate the imaging of the pitting corrosion with the proposed probe. The experimental results further confirm the superiority of the proposed PMEC probe.