Universidade Federal de Sao Joao del-Rei, Universidade Federal de São João del-Rei, Universidade Federal de Sao Joao del-Rei, Universidade Federal do Espírito Santo, Universidade Federal de São João del-Rei, Universidade Federal de São João del-Rei
Polyaniline films were electrodeposited onto carbon steel using different procedures to evaluate the influence of deposition parameters on coating formation and the corrosion rate of the carbon steel coated with the conductive polymer film. Electrodeposition was performed using chronoamperometry in an oxalic acid and aniline solution. Corrosion resistance was evaluated in a 3.5% NaCl solution. The procedures studied assessed how the presence of the passive layer, the solution composition, and the applied potential interfere with the formation of polyaniline films. The morphology of the obtained films was characterized by Scanning Electron Microscopy combined with Energy Dispersive Spectroscopy and by Fourier Transform Infrared Spectroscopy. The electrochemical evaluation of corrosion resistance was performed using Open Circuit Potential, Linear Polarization Resistance, Electrochemical Impedance Spectroscopy, and Potentiodynamic Polarization. The results showed that the deposition parameters were crucial for the quality of the films obtained, especially when applied to substrates previously passivated with a layer of iron oxalate. It was also observed that the polyaniline films reduced the corrosion rate by approximately three times compared to uncoated carbon steel. Furthermore, the corrosion potential showed more negative values for the coated substrate, suggesting that the film acts as cathodic protection for the carbon steel.
