Developing a self-healing anticorrosion coating for steel protection in marine tidal zone

A self-healing anticorrosion protective was developed for steel st-37 exposed to the marine tidal zone, which is composed of a multi-layer polymer coating. The coating includes zinc-rich epoxy primer, self-healing microencapsulated embedded epoxy, and a top coat consisting of polyurethane incorporated with silica nanoparticles. The size of microcapsules decreased with increasing agitation during encapsulation, which varies from 4 to 43 µm. Good performance was observed for producing the encapsulated particles with a size of up to 5 µm and more than 90% loading of the embedded healing agent, in which a 1680 rpm agitation along with a pH of 3 for the synthesis environment and a 130 min for the synthesis duration is set. The optimal amount of microcapsules and silica nanoparticles was 10 and 1.5 wt%, respectively. Also, the promised self-healing anticorrosion coating leads the damaged areas to be fully healed in almost 12 h in the face of harsh conditions. In contrast to the non-self-healing one, the healing ability of the developed self-healing coating shows good barrier properties and leads to a lesser loss of interface adhesion.