Electrochemical impedance spectroscopy (EIS) study of nano-alumina modified alkyd based waterborne coatings

摘要

A nano-composite coating was formed by dispersing nano-Al _2O _3 as pigments in different concentrations, to a specially developed alkyd based waterborne coating. The nano-Al _2O _3 based composite coatings were applied on mild steel substrate by dipping. The dispersion of particles in coating system was investigated by using SEM and AFM techniques. The effect of addition of these nano-pigments on the electrochemical behavior of the coating was investigated in 3.5% NaCl solution, using electrochemical impedance spectroscopy (EIS). It was found that coating modified with higher concentration of nano-Al _2O _3 particles showed comparatively better performance as it was evident from pore resistance (R _p) and coating capacitance (C _c) values after 30 days of exposure. In general, the study showed an improvement in the corrosion resistance of the nano-particle modified coatings as compared to the neat coating, confirming the positive effect of nano-particle addition in coatings.