Novel properties of a conductive polymeric coating with an insulating nanoadditive

Abstract

Today, due to the limitations of hot dip galvanized coating, zinc-rich coating as a suitable alternative coating is used extensively, and the effectiveness of the mixture of a specific amount of zinc as a conductive and zinc oxide as a semiconductive additive to improve the corrosion resistance of these coatings has been illuminated. In this research, we obtained novel corrosion resistance properties for the conductive zinc-rich coating using clay layered silicate additive in spite of its insulating nature. So in this paper, zinc-rich polyurethane nanocomposite samples with addition of various concentrations of nanosilicate planes were prepared by ultrasonication method. Optical microscopy and X-ray diffraction for analysis of the structure and electrochemical impedance spectroscopy, water absorption and conductance for analysis the anticorrosive properties were done. Results showed improvement of corrosion resistance with increasing the value of clay in the coating up to 2 wt%. Since zinc-rich coating is a sacrificial coating dependent on conductivity, it seems insulating additives decreases its functionality, but it is interesting that the corrosion resistance is based on the interaction of two important parameters: barrier effect and conductance effect. Planar structure of clay silicate causes to reasonably increase the barrier effect of the coating. At the same time, sacrificial effect of conductive zinc particles gives unique properties to this new nanocomposite with considering the optimum percentage of clay additive to control the conductivity.