High-Precision Thickness Detection of Coatings Based on Terahertz Propagation Simulation Model

Bin, 程滨 Cheng; Jiaojiao, 任姣姣 Ren; Jian, 顾健 Gu; Lijuan, 李丽娟 Li; Tian-yuan, 高天元 Gao

doi:10.3788/aos202040.1312001

Cited by 4 publications

(3 citation statements)

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“…Studies have shown that the refractive index value of an epoxy resin mixture has little volatility in a certain frequency range [24,25], therefore the refractive index n of the epoxy coating was supposed to not be dependent on frequency. It could be measured first by the experimental test, and subsequently the high-frequency permittivity ε ∞ could be calculated as it approximately equals n 2 .…”

Section: Coating Parameter Settingmentioning

confidence: 99%

Improved Numerical Modeling of Terahertz Wave Propagation in Epoxy Coating with the Finite-Difference Time-Domain Method

Tu,

Zhong,

Zhang

et al. 2023

Coatings

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Electromagnetic theoretical analysis was usually used to investigate the pulsed terahertz wave interaction with the medium. For epoxy coatings, the material dispersion of the coating was often simplified or ignored in the traditional propagation model. It is difficult to elaborate on the propagation mechanism and to differentiate the coating deterioration as serving time increases. An improved propagation model based on the finite-difference time domain was established to characterize the propagation in the epoxy protective coating under broad-band terahertz radiation. Either an intact or defective coating structure was investigated, and the simulated results were compared with the experimental test. The dissipation mechanism was considered in the proposed model. The results indicated that the terahertz reflections varied with the change in optical and dielectric properties caused by coating aging, which influences the intrinsic impedance of the medium. Moreover, it could well elucidate the propagation mechanism of pulsed terahertz waves in rusted, defective coating structures.

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Section: Coating Parameter Settingmentioning

confidence: 99%

Improved Numerical Modeling of Terahertz Wave Propagation in Epoxy Coating with the Finite-Difference Time-Domain Method

Tu,

Zhong,

Zhang

et al. 2023

Coatings

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show abstract

“…The maximum variance of the threes samples is 6.46% (Sample 1), 7.73% (Sample 2), and 6.72% (Sample 3) when compared to the traditional thickness meter. It needs to be pointed out that the resolution of TPI is approximately 20-30 μm and it can meet the requirements of the painting process with the current technology for monitoring the thickness of single-layer and multilayered organic coatings using terahertz technology [7,8].…”

Section: Terahertz Non-destructive Testing Of Multilayered Organic Coatingsmentioning

confidence: 99%

“…Recently, great progress has been made in coating structure analysis, such as coating thickness measurement [6]. Cheng B et al proposed an optimization method to improve the detection resolution of top paint layer [7]. Non-contact measurement of multi-layered coating thickness was also investigated by Lin Y and coworkers [8].…”

Section: Introductionmentioning

confidence: 99%

Non-Destructive Evaluation of Hidden Defects Beneath the Multilayer Organic Protective Coatings Based on Terahertz Technology

Zhong

Luo

et al. 2021

Front. Phys.

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An organic protective coating system plays an important role for the corrosion protection of offshore metallic structures. It is of practical importance to detect possible coating defects and evaluate coating performance for corrosion degradation monitoring. Reliable defect identification can provide timely and effective maintenance to avoid serious consequences. This work investigated various multilayer organic coating systems by terahertz pulse imaging technology and aimed to explore the inspection ability of terahertz non-destructive testing (THz NDT) of protective coatings. Several types of defective coating samples were measured. The comparison of measurements obtained for sites with and without defects was provided. The changes in the signals caused by the presence of defects were explained. Structural analysis, quantitative evaluation, and defect identification were carried out in detail. The results of measurements showed that corrosion defects, paint bulge defects, and paint detachment defects can be distinguished and identified in combination with the causes of defects. It can provide effective technical guidance for terahertz technology to be gradually extended to engineering applications.

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Rapid diagnosis of corrosion beneath epoxy protective coating using non-contact THz-TDS technique

Zhong

Zhang

et al. 2023

Nondestructive Testing and Evaluation

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High-Precision Thickness Detection of Coatings Based on Terahertz Propagation Simulation Model

Cited by 4 publications

References 0 publications

Improved Numerical Modeling of Terahertz Wave Propagation in Epoxy Coating with the Finite-Difference Time-Domain Method

Improved Numerical Modeling of Terahertz Wave Propagation in Epoxy Coating with the Finite-Difference Time-Domain Method

Non-Destructive Evaluation of Hidden Defects Beneath the Multilayer Organic Protective Coatings Based on Terahertz Technology

Rapid diagnosis of corrosion beneath epoxy protective coating using non-contact THz-TDS technique

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