Electrochemical Impedance Spectroscopic Analyses of the Influence of the Surface Nanocrystallization on the Passivation of Carbon Steel in the Pore Solution

This research aimed to apply different models on electrochemical impedance spectroscopy to study the influence of grain refinement and straining obtained from surface mechanical attrition treatment on the passivation of carbon steel in an alkaline solution at open circuit and different passivating potentials. Based on the power law model, the graphical presentation of capacitances at high frequencies and the SIMPLEX method at low frequencies were used to evaluate the electrochemical properties of the interface. The point defect model was used to estimate point defects diffusivity of the passive film in the passivating potential range. Results showed the oxide layer formed on a more strained and grain refined surface was thinner but less porous.