Investigation on corrosion protection mechanism of polyaniline nanoparticles doped with phosphoric acid by scanning Kelvin probe and other electrochemical methods

In this research corrosion protection mechanism of Polyaniline nanoparticles (PANs) doped with phosphoric acid dispersed in the Epoxy–Novolac polymer was investigated. Scanning and transmission electron microscopy proved PANs nanometer size and uniform dispersion in Epoxy. Conductivity, EIS, Potentiodynamic, OCP measurements and Scanning Kelvin Probe technique were used to study the protection mechanism of PANs. It was proved that PANs in the coating stabilize the potential of metal in passive state via formation of protective oxide layer and passivation of pinholes on the carbon steel. Coefficient of variation of surface Volta potentials was suggested as an index for investigation on corrosion uniformity under the coatings in presence of PANs.