Accelerated corrosion of polyaniline-coated steel in high pH media

The corrosion behavior of steel and polyaniline-coated steel in caustic media is presented. DC polarization curves show steel is protected from excessive corrosion forming a passive oxide layer in a caustic solution even in the presence of dilute chloride ion. A iron(II) oxalate tie-layer deposited on steel prior to aniline polymerization corrodes more slowly than the bare steel in a chloride-free electrolyte. Chloride ion accelerates corrosion of the oxalate layer prior to the formation of the oxide barrier layer. The polyaniline (PANi)-coated steel exhibited the lowest corrosion rate and the chloride ion had a negligible effect on the corrosion performance.