Improving corrosion protection performance of polypyrrole coating by tungstate ion dopants

Abstract

Polypyrrole ( PPy ) and polypyrrole-tungstate ( PPy - ) coatings were electrodeposited on mild steel (MS) electrodes by cyclic voltammetry (CV) technique. Aqueous oxalic acid solution was used as sup- porting electrolyte for these processes. For the electrodeposition of PPy - , tungstate anion was added to the supporting electrolyte. The surface morphologies of the two types of coated-samples were characterized by scanning electron microscopy (SEM) and line-scan EDX analysis. Furthermore, open circuit potential (OCP) monitoring, polarization and electrochemical impedance spectroscopy methods were performed for comparing the corrosion protection performances. Corrosion studies indicate that dopants can improve corrosion protection properties by taking part in: (i) the passivation process occurred prior to electrodeposition process, (ii) the electrosynthesis process and incorporation into polymer chain.