Nondestructive testing of marine protective coatings using terahertz waves with stationary wavelet transform

Wanli Tu, Shuncong Zhong, Yaochun Shen, Atilla Incecik

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43 Citations (Scopus)
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Terahertz wave propagation in marine protective coatings and its non-destructive testing (NDT) capability were studied by the finite difference time domain (FDTD) method. The FDTD model was used to calculate the propagation and reflection of THz radiation from marine protective coatings. The reflected terahertz waves could be employed in coating thickness analysis of the paint layers. In order to clearly identify the interface between antifouling and anticorrosive coatings, stationary wavelet transform (SWT) approach was applied to decompose the obtained terahertz impulse functions into approximation and detail coefficients; SWT detail coefficients were used for the feature extraction of the coating thickness. SWT provides a more accurate identification of salient features in a signal, such as the weak feature between antifouling and anticorrosive coatings. We found that the developed model and SWT-based algorithms could be used to evaluate the occurrence of defects beneath the coatings (e.g., paint-off and corrosion defects). The proposed method provides the solution for coating thickness of marine protective coatings and it would benefit the effective maintenance to avoid coating failure and facilitate marine protective coating design. Therefore, non-destructive testing and evaluation of marine protective coating system by terahertz waves with SWT could be recommended for engineering applications.

Original languageEnglish
Pages (from-to)582-592
Number of pages11
JournalOcean Engineering
Early online date11 Dec 2015
Publication statusPublished - 1 Jan 2016


  • finite difference time domain
  • marine protective coatings
  • non-destructive testing
  • stationary wavelet transform
  • terahertz wave


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