The effect of pollypyrole and nickel+pollypyrole coatings on AISI 304 stainless steel corrosion behaviour

Polypyrrole (PPy) and nickel+PPy coatings have been occured on 304 steel surface by cyclic voltammetry technique in aqueous oxalic acid solutions and as the supporting electrolytes are used saccharin and NaNO3. Corrosion behavior of the polypyrrole and nickel+PPy coated 304 steel electrodes was investigated using linear anodic polarization, Tafel extrapolation and Electrochemical Impedance Spectroscopy (EIS) techniques in various aqueous corrosive solutions. The polypyrrole coated samples have been characterized by Scanning Electron Microscope (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). SEM analysis showed that PPy structure depends closely on the electrochemical conditions. Additionally, it is seen in FTIR analysis, characteristic polypyrrole absorption bands have occurred in all the coated surfaces. Tafel analyses and open-circuit potential datas revealed that the polypyrrole and nickel+PPy coatings effectively protects the steel substrate from corrosion in H2SO4 ve NaOH solutions. However, the corrosion protection properties were reduced with longer immersion times. Nickel+PPy coatings more effectively protects the steel substrate from corrosion than polypyrrole