A review on anti-corrosion self-healing epoxy coatings

Epoxy resins are widely used as coating to protect metals in various applications. The properties such as very good processability, excellent chemical resistance, good insulation against electricity, and strong adhesion to non-homogeneous materials have caused epoxy materials to be widely considered in the coating industries. Epoxy coatings are susceptible to damage such as microcracking. These types of damages cause defects in the coating and reduce the appearance (beauty) and mechanical strength of the coating. Also, the penetration of water, oxygen and corrosive agents to the surface of the metal is accelerated. As a result, the local corrosion occurs in the metal. The repair process of polymer coatings is time-consuming, expensive, and in many cases it is impossible to detect the damages and access them for repair. Therefore, it is very important to find a solution to automatically repair the microcracks without any type of human intervention and the replacement of new components. Therefore, this can be possible by designing self-healing intelligent systems. The most common method of preparing self-healing coatings is microencapsulation of healing agent in polymer or mineral shells and embedding the prepared microcapsules in the epoxy matrix. The self-healing properties of the epoxy coatings can be investigated with electrical impedance spectroscopy and salt spray tests. In this research, the studies on self-healing epoxy coatings have been reviewed.