The current oil tanker is constructed as a double hull structure which consists of oil tank and water ballast tank. Also their interior walls are coated with epoxy paint to prevent corrosion. The cracks developed on the epoxy coating cause the corrosion of the interface and the break-off of the epoxy coating. The repair of the interior walls costs lots of labor and money. The crack of the interior walls is caused by the temperature changes during operation and the stress concentration on the welding line. The stress concentration level is dependent of the thermo-mechanical properties of the epoxy paint such as the coefficient of thermal expansion and the glass transition temperature. Once the coating crack occurs, the crack propagates to the adhesion interface and the delamination of the coating around the crack occurs due to the peel stress which is developed at the end of the fracture surface when the coating material expands and contracts due to the temperature change. Moisture penetration through the interface causes the corrosion of the substrate and the break-off of the epoxy coating, which is closely related to the interfacial morphology formed by the surface treatment.
In this thesis, after the thermo-mechanical properties of the epoxy paint were measured, the residual stress induced by the cure shrinkage and the thermal stress induced by the temperature change were evaluated by the finite element analysis using the measured data. Also, the pull-off tests were performed to investigate the deterioration of the bonding strength of epoxy coating with moisture absorption. From the investigation, it was found that the thermo-mechanical properties such as CTE and $T_g$ of the coating materials had dominant effects on the crack resistance rather than the cure shrinkage, the moisture penetration to the bonding interface caused the interfacial failure and the significant deterioration of bonding strength.
