NONDESTRUCTIVE EVALUATION OF AN EPOXY-BASED COATING BY OPTICAL INTERFEROMETRY TECHNIQUES

A study on evaluating an epoxy-based coating was conducted. The study aimed to determine the performance of the coating on a low carbon stee l as a result of chemical contaminations. Coated samples were tested i n a local tap water by using the method of real time-holographic inter ferometry. A mathematical model was used along with the obtained exper imental data. The model described processes of detecting the early cor rosion of the steel under the coatings by holographic interferometry. Consequently, the holographic interferometry technique was found very useful in detecting the early corrosion processes of the coated steel. Also, a relationship between the displacement of the coating, due to metal corrosion under the coating, and corrosion current density of th e coated steel was established for the epoxy-based coating with and wi thout an addition of sodium chloride to the coating.