|
Optical shearography techniques were used for the first time to measure the surface resistivity/conductivity of different
organic-thin films. Different organic coatings i.e., ACE Premium- gray, white, and beige Enamels (spray
coatings), on a metallic alloy, i.e., a carbon steel, were 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 coatings, which amounts to the thermal
deformation (strain) with respect to the applied temperature range. Then, the alternating current (AC) impedance
(resistance) of the coated samples was determined by the technique of electrochemical impedance spectroscopy (EIS) in
3.5 % NaCl solution at room temperature. In addition, a mathematical model was derived in order to correlate between
the AC impedance (resistance) and to the surface (in-plane) displacement of the samples in solutions. In other words, a
proportionality constant (surface resistivity or conductivity=1/ surface resistivity) between the determined AC impedance
(by EIS technique) and the in-plane displacement (by the optical interferometry techniques) was obtained. Consequently
the surface resistivity (ρ) and conductivity (σ) of the coated samples in solutions were obtained. Also, electrical
resistivity values (ρ) from other source were used for comparison with the calculated values of this investigation. This
study revealed that the measured values of the resistivity for the ACE Premium - gray, white, and beige coatings
were carried out for the first time. No data on the values of (ρ) were found in literature for the same coatings, using
direct current (DC) methods. However, the value range of (ρ) of all investigated coatings, 0.25×108 - 0.27×1010 Ω-cm
was found in the insulator range.
|
