No abstract

No abstract

No abstract

Nano zinc oxide-containing epoxy-based coatings were prepared by co-deposition of zinc oxide nano particles and epoxy-based cathodic electrodeposition paint. The films were exposed to UV radiation for different periods and the corrosion resistance properties of the exposed films were evaluated by electrochemical impedance spectroscopy. It was found that the nano zinc oxide stabilized coatings maintain their protective properties even after a prolonged exposure to UV light. The more prolonged retention of protection properties of the coating was assigned to the morphology of the film containing nano ZnO after exposure to UV light. Nano ZnO stabilized coatings show a uniform degradation of the film surface while non-stabilized coating exhibit deep cracks which results in deterioration of the film integrity. UV exposure of non-stabilized films was found to result in formation of deep cracks and non-uniform photodegradation in epoxy coating.Organic coatings are widely used in protection of metallic substrate against corrosion. 1 It is generally accepted that the coating efficiency for outdoor applications depends on its weathering resistance, barrier and adhesion properties of the coating and the degree of aggressiveness of the environment and so on. Many factors may accelerate coating degradation namely ultraviolet (UV) radiation, water and moisture, elevated temperatures, chemicals, thermal variations, presence of molecular and singlet oxygen, ozone and abrasion or other mechanical stresses. Among the above mentioned factors, degradation of organic coatings is mostly promoted by simultaneous effect of: UV radiation, moisture, heat and chemicals. In a barrier protective coating, as the polymeric backbone of the coating film is slowly broken down by UV light, the coating's barrier properties is worsened. The ultraviolet range of the sunlight spectrum is an important damaging factor for the exterior coatings. [2][3][4][5] To decrease the probability of occurrence of such failures, coatings that are exposed to UV light during their service life are mostly formulated based on UV-resistant polymeric binders, such as acrylics and aliphatic polyurethanes. 6

No abstract