Characterization of Coatings on Magnetic Metals Using Swept-Frequency Eddy Current and Transient Eddy Current Methods

Tai, Cheng‐Chi; Rose, James H.; Moulder, John C.

doi:10.1007/978-1-4615-5947-4_208

Cited by 6 publications

(1 citation statement)

References 6 publications

(8 reference statements)

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“…Eddy current methods have been used in a range of technological applications such as thickness measurement, quality inspection, coating and surface treatment [1][2][3][4][5]. Both single-frequency eddy current techniques, where the coil is excited with a sinusoidal signal, and pulsed eddy current (PEC) techniques [6][7][8][9], where the coil is excited with a rectangular stimulus, have been developed. Conventional single-frequency eddy current techniques typically interrogate samples at a fixed frequency, which translates into a certain depth of sensitivity according to electromagnetic theory.…”

Section: Introductionmentioning

confidence: 99%

A multi-frequency impedance analysing instrument for eddy current testing

Yin

Dickinson

Peyton

2006

Meas. Sci. Technol.

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This paper presents the design of a high-performance multi-frequency impedance analysing instrument (MFIA) for eddy current testing which has been developed primarily for monitoring a steel production process using an inductive sensor. The system consists of a flexible multi-frequency waveform generator and a voltage/current measurement unit. The impedance of the sensor is obtained by cross-spectral analysis of the current and voltage signals. The system contains high-speed digital-to-analogue, analogue-to-digital converters and dual DSPs with one for control and interface and one dedicated to frequency-spectra analysis using fast Fourier transformation (FFT). The frequency span of the signal that can be analysed ranges from 1 kHz to 8 MHz. The system also employs a high-speed serial port interface (USB) to communicate with a personal computer (PC) and to allow for fast transmission of data and control commands. Overall, the system is capable of delivering over 250 impedance spectra per second. Although the instrument has been developed mainly for use with an inductive sensor, the system is not restricted to inductive measurement. The flexibility of the design architecture is demonstrated with capacitive and resistive measurements by using appropriate input circuitry. Issues relating to optimizing the phase of the spectra components in the excitation waveform are also discussed.

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Section: Introductionmentioning

confidence: 99%

A multi-frequency impedance analysing instrument for eddy current testing

Yin

Dickinson

Peyton

2006

Meas. Sci. Technol.

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Thickness measurement of non-magnetic plates using multi-frequency eddy current sensors

Yin

Peyton

2007

NDT & E International

164

109

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Analysis of the Lift-off Effect of Phase Spectra for Eddy Current Sensors

Yin

Binns

Dickinson

et al.

2005 IEEE Instrumentationand Measurement Technology Conference Proceedings

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This paper presents an analytical model which describes the inductance change when a double air-cored coil sensor is placed next to a conducting plate. Analysis of the analytical model reveals that the phase signature of such sensor is virtually lift-off independent. This finding is verified by numerical evaluations. This paper also finds that the phase signature of a ferrite U-cored sensor can be approximated by that of a double aircored sensor of similar size, and therefore possesses similar lift-off independent property. Measurements made with a sample U-cored sensor next to plates of non-magnetic and magnetic materials verified the theoretical results .

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Characterization of Coatings on Magnetic Metals Using Swept-Frequency Eddy Current and Transient Eddy Current Methods

Cited by 6 publications

References 6 publications

A multi-frequency impedance analysing instrument for eddy current testing

A multi-frequency impedance analysing instrument for eddy current testing

Thickness measurement of non-magnetic plates using multi-frequency eddy current sensors

Analysis of the Lift-off Effect of Phase Spectra for Eddy Current Sensors

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