Electrochemical synthesis and corrosion performance of polyaniline (PANI)coating on iron substrates

ABSTRACT PhD THESIS ELECTROCHEMICAL SYNTHESIS AND CORROSION PERFORMANCE OF POLYANILINE (PANI) COATING ON IRON SUBSTRATES ALI TUNCAY OZYILMAZ DEPARTMENT OF CHEMISTRY INSTITUTE OF NATURAL AND APPLIED SCIENCES UNIVERSITY OF ÇUKUROVA Supervisor: Prof.Dr. Birgül YAZICI Year: 2004 Pages: 178 Jury : Prof.Dr. Birgül YAZICI Prof. Dr. Mehmet ERBİL Prof.Dr. Nureddin ÇOLAK Prof.Dr. Sermin ÖRNEKTEKİN Assosc.Prof. Dr. İlyas DEHRİ In this study, Polyaniline (PANI) films were deposited by using potentiodynamic, potentiostatic and galvanostatic techniques on stainless and mild steel samples from aqueous solutions of oxalic acid. The PANI films obtained using potentiodynamic tecnique were found to be more quality than other techniques. Therefore, the mild steel was coated using potentiodynamic tecnique in p- toluenesulfonic acid solution as an electrolyte medium for the purpose of comparison. To obtain homogenous and strongly adherent films, the electrode surface should be first passivated before oxidation of aniline. The passivation of steels was provided by the formation of a FeC2Û4 complex on the surface of the electrodes. The corrosion performances of steel samples coated with PANI were investigated in hydrochloric and sulphuric acid solutions. Nyquist curves showed that the polarization resistance of PANI coated mild steels were relatively lower with respect to stainless steels. The protection mechanism of stainless steel depended on the quality of the oxide film, which should be obtained by PANI acting with catalytic effect. Keywords: Polyaniline, Oxalic acid, Potentiodynamic, Stainless and mild steel II