EVALUATION OF CORROSION PROTECTION PERFORMANCE OF CONDUCTING POLYANILINE/NANO-ZINC PHOSPHATE COATED LOW CARBON STEEL BY IMPEDANCE SPECTROSCOPY

Conducting polyaniline nano zinc phosphate composite was prepared by chemical oxidative method. The epoxy based paint containing 2 wt % conducting polyaniline nano zinc phosphate composite pigment was applied on low carbon steel samples. Corrosion protection performance the painted low carbon steel samples in 3.5 wt % sodium chloride solution was evaluated by impedance spectroscopy and alternating immersion testing machine. Conducting polyaniline nano zinc phosphate based paint can protect low carbon steel up to 48 hours in 3.5 wt % NaCl aqueous medium and withstand drying - wetting cycles in the atmosphere. The protection is based on simultaneously operating mechanisms viz. enhanced barrier protection, passivation and release of inhibiting phosphate ions when in contact with corrosive media.