Electrodeposition mechanism, adhesion and corrosion performance of polypyrrole and poly(N-methylpyrrole) coatings on steel substrates

By Su, Wencheng & Iroh, Jude O
Published in Synthetic Metals NULL 2000

Abstract

Polypyrrole and poly(N-methylpyrrole) coatings have been successfully electrodeposited on steel substrates from aqueous oxalate solutions. In acidic solutions, the electrodeposition process was characterized by three distinct stages. In this work the electrodeposition process was first investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and FTIR techniques. The adhesion and corrosion performance of the electrodeposited coatings were then evaluated by single lap shear tests and tafel tests, respectively. Our results reveal that deposition of FeC2O4·2H2O crystal layer first established the passivation of steel at the end of the first two stages, but the formed FeC2O4·2H2O passive layer is subsequently decomposed followed by electropolymerization of pyrrole. Our results also show that electrochemical process parameters had significant effects on the adhesion and corrosion performance of the electroposited polypyrrole and poly(N-methylpyrrole) coatings. Polypyrrole coatings exhibited better adhesion and corrosion performance than poly(N-methylpyrrole) coatings.

Read Article » Back