Unraveling the complex infiltration and repairing behaviors in defect coatings

Organic coatings are commonly used to protect the metals or alloys from corrosion. However, defects such as scratches or natural aging of the coating can induce unexpected diffusion paths for the corrosive media, so the wettability of repairing liquids and the selection of suitable repairing liquids are crucial. In this study, we systematically investigated the capillary impregnation phenomenon by using liquids with various surface tensions and glass capillaries with different surface energies. We utilized this regularity to instruct the defects repairing process. By using an ultra-depth field microscope, scanning electron microscope, and electrochemical analysis, two kinds of repairing liquids, high surface tension liquid (HSTL) and low surface tension liquid (LSTL), were investigated for repairing man-made defects of coatings. Our results showed that the substrate and the surface energy of the liquids significantly influence the infiltration of the repair liquid. By effectively leveraging the relationship between the repair liquid and the substrate, the repair agent can not only establish a uniform and dense repairing layer but also notably enhance the corrosion resistance of the defective coating. This study provides valuable insights into the repairing of coating defects, as well as liquids transportation, microfluidic chip design, and surface modification of microporous materials.