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Quantifying the Relative Thickness of Conductive Ferromagnetic Materials Using Detector Coil-Based Pulsed Eddy Current Sensors

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Eddy Current Testing of Conductive Coatings Using a Pot-Core Sensor.

Grzegorz Tytko¹

¹Faculty of Automatic Control, Electronics and Computer Science, Silesian University of Technology, Akademicka 16, 44-100 Gliwice, Poland.

Sensors (Basel, Switzerland)

|January 21, 2023

Summary

A novel eddy current system featuring a pot-core sensor and analytical model enhances nondestructive testing for thin layers and thermal barrier coatings (TBC). This system achieves high sensitivity and accuracy, improving defect detection and structural integrity assessments.

Keywords:

analytical modeling coatings eddy current testing pot-core sensor sensor impedance thermal barrier coating truncated region eigenfunction expansion method

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Area of Science:

Materials Science
Electrical Engineering
Nondestructive Testing

Background:

Thin layers and thermal barrier coatings (TBC) are crucial in various industries for protection and insulation.
Nondestructive testing (NDT) is vital for assessing the dimensions, condition, and defects in these layered structures.
Existing NDT methods may lack sufficient sensitivity for very thin layers.

Purpose of the Study:

To introduce a novel eddy current system for the NDT of thin layers and coatings.
To develop and validate an analytical model for a pot-core sensor.
To demonstrate the enhanced sensitivity and accuracy of the proposed system compared to conventional sensors.

Main Methods:

Development of an analytical model using the truncated region eigenfunction expansion (TREE) method.
Implementation of the analytical model in Matlab for calculating sensor impedance.
Experimental validation of the model with thin layers (thickness > 0.1 mm).
Verification of thermal barrier coating (TBC) calculations using finite element method (FEM) in Comsol Multiphysics.

Main Results:

Closed-form formulas for sensor impedance were derived and implemented.
Calculated sensor impedance values showed less than 4% error when compared to experimental and numerical results.
The pot-core sensor demonstrated significantly higher sensitivity for thin-layer testing than air-core and I-core sensors.

Conclusions:

The developed eddy current system provides an accurate and sensitive method for NDT of thin layers and coatings.
The pot-core sensor offers superior performance for detecting defects in thin structures.
This technology can reduce risks associated with failures and accidents in industries utilizing thin-layer coatings.