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In the present work, the temperature versus thermal deformation (strain) with respect to time, of
different coating films were studied by a non-destructive technique (NDT) known as shearography. An
organic coating, i.e., ACE Premium Enamel, on a metallic alloy, i.e., a carbon steel, was investigated at a
temperature range simulating the severe weather temperatures in Kuwait especially between the daylight and
the night time temperatures, 20-60 °C. The investigation focused on determining the in-plane displacement of
the coating, which amounts to the thermal deformation (strain) with respect to the applied temperature range.
Furthermore, the investigation focused on determining the thermal expansion coefficients of coatings, the
slope of the plot of the thermal deformation (strain) versus the applied temperature range. In other words, one
could determine, from the decreasing value of the thermal expansion coefficients of coatings, a critical (steady
state) value of the thermal expansion coefficients of coatings, in which the integrity of the coatings can be
assessed with respect to time. In fact, determination of critical (steady state) value of the thermal expansion
coefficients of coatings could be accomplished independent of parameters, i.e., UV exposure, humidity,
exposure to chemical species, and so on, normally are considered in conventional methods of the assessment
of the integrity of coatings. In other words, with the technique of shearography, one would need 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. Furthermore, results of shearography
indicate that the technique is very useful NDT method not only for determining the critical value of the
thermal expansion coefficients of different coatings, but also the technique can be used as a 2D- microscope
for monitoring the deformation of the coatings in real-time at a submicroscopic scale.
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