Abstract

MUNOT, H.; DESHPANDEA, P.  and  DELIGEORGIEV, T.. Electrochemical Investigations on Semi-conducting Properties of a Passive Film on Conducting Polypyrrole Coated Low Carbon Steel in a Simulated Concrete Pore Solution. Port. Electrochim. Acta [online]. 2019, vol.37, n.1, pp.43-50. ISSN 0872-1904.  https://doi.org/10.4152/pea.201901043.

Conducting polypyrrole was synthesized by the chemical oxidative method, and characterized using FTIR spectroscopy. An epoxy based paint containing conducting polypyrrole was prepared and applied on a low carbon steel sample, using a film applicator. The uncoated and painted steel samples were kept immersed in the simulated concrete pore solution. The Mott-Schottky technique was used to study the passive film formation on an uncoated low carbon steel, and the conducting polypyrrole coated low carbon steel was immersed in a simulated pore solution. The peaks at 1447 cm^-1 and 1149 cm^-1 are the responsible peaks of protonated nitrogen atoms in polypyrrole. The peak at 1538 cm^-1 refers to the C-C stretching vibration in the pyrrole ring, and the peak at 1042 cm^-1 denotes the C-H stretching vibration in the pyrrole ring. The M-S slope indicates that the passive film on uncoated low carbon steel exhibited n-type semi-conductive behaviour, and that the polypyrrole coating exhibited p- n type behaviour. However, with the increasing chloride contents and immersion time, the polypyrrole coating exhibited only p type behaviour.

Keywords : corrosion; passive film; concrete pore solution; rebar; conducting polypyrrole.

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