Electrochemical study of polymer and ceramic-based nanocomposite coatings for corrosion protection of cast iron pipeline

Coating is one of the most effective measures to protect metallic materials from corrosion. Various types of coatings such as metallic, ceramic and polymer coatings have been investigated in a quest to find durable coatings to resist electrochemical decay of metals in industrial applications. Many polymeric composite coatings have proved to be resistant against aggressive environments. Two major applications of ferrous materials consist of their use in marine environment and in oil & gas industry. Knowing the corroding behavior of ferrous based materials during exposure to these aggressive applications, an effort has been made to protect the material by polymeric and ceramic based coatings reinforced with nano materials. Uncoated and coated cast iron pipeline material was investigated during for corrosion resistance by employing EIS (electrochemical impedance spectroscopy) and electrochemical DC corrosion testing using 'three electrode system'. Cast iron pipeline samples were coated with Polyvinyl Alcohol/Polyanline/FLG (Few Layers Graphene) and TiO2/GO (graphene oxide) nanocomposite by dip coating. The EIS data indicated better capacitance and higher impedance values for coated samples compared with the bare metal, depicting enhanced corrosion resistance against seawater and 'produce water' of a crude oil sample from a local oil rig; Tafel scans confirmed a significant decrease in corrosion rate of coated samples