Journal of Failure Analysis and Prevention

, Volume 10, Issue 5, pp 427–433 | Cite as

Critical Assessment of the Integrity of Thin Organic Films by Shearography

  • K. Habib
Technical Article---Peer-Reviewed


The temperature versus thermal deformation (strain) with respect to time, of different coating films was studied by a non-destructive technique (NDT) known as shearography. The behavior of organic coatings, i.e., epoxy, a white enamel, or a yellow acrylic lacquer on carbon steels, was investigated at a temperature range simulating the severe weather temperatures in Kuwait especially 20–60 °C differences between the daylight and the night time temperatures. The investigation focused on determining the in-plane displacement of the coatings, which amounts to the thermal deformation that results from the applied temperature range. Furthermore, the investigation also focused on determining the thermal expansion coefficients of coatings and the slope of the plot of the thermal deformation versus the applied temperature range. A critical (steady state) value of the thermal expansion coefficients of coatings was used to determine the integrity of the coatings with respect to time. This value was determined from the decreasing, time-dependent value of the thermal expansion coefficients of coatings. In fact, determination of critical (steady state) value of the thermal expansion coefficients of coatings could be accomplished independent of parameters such as UV exposure, humidity, presence of chemical species, and other parameters normally considered in conventional methods of the assessing of the integrity of coatings. By using the technique of shearography, one needs only to determine the critical (steady state) value of the thermal expansion coefficients of coatings, regardless of the history of the coating, in order to assess the integrity of coatings. These results indicate that the technique is a very useful NDT method for determining the critical value of the thermal expansion coefficients of different coatings and can be used as a 2D-microscope for monitoring the deformation of the coatings in real-time at a submicroscopic scale.


Shearography Optical interferometry Thermal expansion coefficient In-plan displacement High temperatures Carbon steel Organic Coating Epoxy 


  1. 1.
    Erf, K.R.: Speckle Metrology, p. 2. Academic Press, New York (1978)Google Scholar
  2. 2.
    Habib, K.: Thermally induced deformations measured by shearography. Opt. Laser Technol. 37, 509–512 (2005)CrossRefADSGoogle Scholar
  3. 3.
    Habib, K.: Measurement of thermal expansion coefficients of thin film of different organic coatings by shearography. Key Eng. Mater. 321–323, 67–70 (2006)CrossRefGoogle Scholar
  4. 4.
    Lambourne, R.: Paint and Surface Coatings: Theory and Practice. Wiley, New York (1987)Google Scholar
  5. 5.
    Schweitzer, P.: Mechanical and Corrosion Resistance Properties of Plastics and Elastomers. Marcel Dekker Inc., New York (2000)Google Scholar
  6. 6.
    Zhang, H., Ke, J.: Determination of residual stress by laser speckle shearing interformetry and hole drilling method. J. Exp. Mech. 1, 181–188 (1986)Google Scholar
  7. 7.
    Shigley, J.: Mechanical Engineering Design, 3rd edn, pp. 67–69. McGraw-Hill, New York (1978)Google Scholar

Copyright information

© ASM International 2010

Authors and Affiliations

  1. 1.Materials Science Laboratory, Department of Advanced SystemsKISRSafatKuwait

Personalised recommendations