Evaluation of Coating Thickness Using Lift-Off Insensitivity of Eddy Current Sensor

Meng, Xiaobai; Lü, Mingyang; Yin, Wuliang; Bennecer, Abdeldjalil; Kirk, K.J.

doi:10.3390/s21020419

Cited by 24 publications

(11 citation statements)

References 51 publications

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“…Therefore, some researchers have proposed a beneficial method to overcome the lift-off problem. Methods used in reducing the lift-off effect includesthe liftoff point of intersection (LOI) [18] [19], dual excitation frequency [1], normalization technique [3], Dodd and Deeds method [20]. These techniques have also been applied to measuring coating and thickness and identifying defects in metal testing.…”

Section: Eddy Current Testingmentioning

confidence: 99%

Lift-Off Effect Evaluation by Using Eddy Current Testing Technique on Copper (C101)

Sulaiman¹,

Harun²,

Eldy³

2023

IJETAE

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This study aims to develop an eddy current testing (ECT) probe that generates eddy current signals when a coil is placed above copper101 metal testing with and without nonconductive coating and the presence of lift-off height, i.e., 0, 2.5, 5.0, 7.5, and 10.0 0.5 mm. Then, the metal test with a variety of thicknesses, i.e., 1.5, 3.0, and 5.0 0.5 mm, and with varies of surface defects, i.e., 10, 20, and 30  0.5 mm, engraved on the metal testing. The coil probe is a rodshaped solenoid coil designed with an iron core with 65 mm length, 5 mm area, and 200 N turns. It demonstrates how the rod-shaped solenoid coil may be used to detect various surface defects on copper101 (C101). The optimal frequencies for C101 are 7.850 MHz. In conclusion, the output voltage signals for larger surface defect sizes increase but decrease as the thickness becomes thicker. Furthermore, as the lift-off height increases, the output voltage for both coated and non-coated metal decreases accordingly. Therefore, besides comparing the output voltage for coated and non-coated metals, there are minor differences which shows that the ECT technique in this studyis capableto detect surface defects appropriately.

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Section: Eddy Current Testingmentioning

confidence: 99%

Lift-Off Effect Evaluation by Using Eddy Current Testing Technique on Copper (C101)

Sulaiman¹,

Harun²,

Eldy³

2023

IJETAE

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“…As a consequence, in such cases, the impedance value is different from that of the tested component without the defect. This property also makes it possible to identify conductive objects [ 10 , 11 , 12 ] and to determine their thickness [ 13 , 14 ], radius [ 15 , 16 ], magnetic anisotropy [ 17 ] or electrical conductivity [ 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

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

Tytko

2023

Sensors

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Conductors consisting of thin layers are commonly used in many industries as protective, insulating or thermal barrier coatings (TBC). Nondestructive testing of these types of structures allows one to determine their dimensions and technical condition, while also detecting defects, which significantly reduces the risk of failures and accidents. This work presents an eddy current system for testing thin layers and coatings, which has never been presented before. It consists of an analytical model and a pot-core sensor. The analytical model was derived through the employment of the truncated region eigenfunction expansion (TREE) method. The final formulas for the sensor impedance have been presented in a closed form and implemented in Matlab. The results of the calculations of the pot-core sensor impedance for thin layers with a thickness above 0.1 mm were compared with the measurement results. The calculations made for the TBC were verified with a numerical model created using the finite element method (FEM) in Comsol Multiphysics. In all the cases, the error in determining changes in the components of the pot-core sensor impedance was less than 4%. At the same time, it was shown that the sensitivity of the applied pot-core sensor in the case of thin-layer testing is much higher than the sensitivity of the air-core sensor and the I-core sensor.

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“…According to Lentz’s rule, the secondary magnetic field is directed opposite to the primary field and thus causes a change in the impedance of the coil. This property makes it possible to detect defects in conductive objects [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ] and determine their geometric dimensions [ 20 , 21 , 22 , 23 , 24 , 25 ], magnetic permeability [ 26 , 27 , 28 ], or electrical conductivity [ 29 , 30 , 31 ]. The changes in the impedance components of the sensor, and therefore the sensitivity of the measurement, strongly depends on the frequency of the current that excites the eddy currents and on the geometry of the sensor.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Properties of Eddy Current Sensors Based on Their Equivalent Parameters

Dziczkowski

Tytko

2023

Sensors

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This paper presents a practical way of using the method of evaluating the metrological properties of eddy current sensors. The idea of the proposed approach consists of employing a mathematical model of an ideal filamentary coil to determine equivalent parameters of the sensor and sensitivity coefficients of tested physical quantities. These parameters were determined on the basis of the measured value of the real sensor’s impedance. The measurements were carried out with an air-core sensor and an I-core sensor while they were positioned at different distances from the surface of tested copper and bronze plates. An analysis of the influence of the coil’s position in relation to the I core on the equivalent parameters was also carried out, and the interpretation of the results obtained for various sensor configurations was presented in a graphical form. When equivalent parameters and sensitivity coefficients of examined physical quantities are known, it is possible to compare even very different sensors with the employment of one measure. The proposed approach makes it possible to make a significant simplification of the mechanisms of calibration of conductometers and defectoscopes, computer simulation of eddy current tests, creating the scale of a measuring device, and designing sensors.

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Evaluation of Coating Thickness Using Lift-Off Insensitivity of Eddy Current Sensor

Cited by 24 publications

References 51 publications

Lift-Off Effect Evaluation by Using Eddy Current Testing Technique on Copper (C101)

Lift-Off Effect Evaluation by Using Eddy Current Testing Technique on Copper (C101)

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

Evaluation of the Properties of Eddy Current Sensors Based on Their Equivalent Parameters

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