In the present work, the temperature versus thermal Ldformation (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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