Preparation and Corrosion Resistance of Manganese Sulfate Doped Polypyrrole Film

Direct contact oxidation technology was used to prepare manganese sulfate doped polypyrrole film on the surface of stainless steel. The microstructure and corrosion resistance of manganese sulfate doped polypyrrole film were tested by cyclic voltammetry, microstructure observation, potentiodynamic polarization curve and electrochemical impedance spectroscopy. The results show that the doping of manganese sulfate changed the structure of polypyrrole and enhanced the compactness of film structure, which made the manganese sulfate doped polypyrrole film had good corrosion resistance and played a role in protection of stainless steel. Compared with the bare stainless steel, the free corrosion potential increased by about 1.0 V and free corrosion current density decreased by about 3 orders of magnitude after the surface of stainless steel covered with manganese sulfate doped polypyrrole film.