Enhanced anticorrosion performance of epoxy primer coating on zinc in 3.5% NaCl by micro and nano particulates of biopolymers

Anticorrosive coatings are extensively used to protect metals and alloys, especially in the marine environment. This study reports the enhancement of coating performance of epoxy primer coating on zinc in 3.5% NaCl at 303 K by impregnating the epoxy primer with micro and nano particulates of biopolymers. Initially, conditions were standardized to achieve optimum efficiency of Maltodextrin (MLD) and Glycogen (GLY) for corrosion of zinc in 3.5% NaCl. The optimum concentration of inhibitors was then added to the epoxy primer coating a applied on zinc. Anti-corrosion performance of epoxy primer with biopolymer was compared with that of standard coating, which was devoid of biopolymers. The coating characteristics were further enhanced by incorporating nanoparticles of MLD and GLY into the epoxy primer matrix. Potentiodynamic polarization measurement (PDP) and Electrochemical impedance spectroscopy (EIS) were employed to study corrosion rate measurement. Detailed surface morphology was studied using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) techniques. Electrochemical and surface studies clearly demonstrated the capability of micro and nanosized biopolymers in improving the anti-corrosion performance of the coating. The average efficiency of epoxy primer coating improved to a considerable extent by studying biopolymers. The overall efficiency of the coating formulation was found to be 99.5%. Surface morphology studies showed that coating thickness increased to 32.1 µm from 27.2 µm after incorporating biopolymers. In addition to this, there was a remarkable change in the surface roughness of epoxy primer coating in contact with 3.5% NaCl after the addition of biopolymers into it. The coating formulation developed turned out to be eco-friendly with significant environmental benefits.