Effect of photo-radiation on anti-corrosion and protection performance of acrylic polyurethane coating

To evaluate the aging behavior of acrylic polyurethane coating/carbon steel system, an artificial accelerated aging test was carded out with the aid of a xenon lamp. The aged coatings were characterized with Fourier transform infrared spectroscopy (FTIR), optical microscope and vancometer. The corrosion resistance of the aged coatings was evaluated by salt spray test, and the effect of photo-radiation on the corrosion of the metal underneath the coating was investigated preliminary. The results show that the coatings with different aging periods all keep good protection state after salt spray test. However, the metal underneath the coating is corroded more severely with the increase of aging time. It can be concluded that the C-N bond of the coating breaks after the exposure to photo-radiation, which causes the increase in surface roughness and the decrease in gloss with the increase of aging time. Furthermore, these surface changes build the access to the underneath metal, which accelerates the penetration of medium into the coating and therefore makes the metal corrode severely.