The electrochemical impedance of polarized 316L stainless steel: Structure‐property‐adsorption correlation

Abstract Electrochemical (EC) impedance and polarization data were synergistically coupled with AFM micrographs providing insight on the polarized alloy–electrolyte interface. Several regions of oxide topography/ impedance characteristic were apparent on a 316L SS surface. A relatively rough surface with apparent EC reaction products was observed below −500 mV. Smooth surfaces were seen from −500 mV to 200 mV. A transition region which displayed the aggregation of particles on the surface was seen from 200 mV to 600 mV. Above 600 mV these particles disappeared revealing a smooth topography. These topographical observations matched closely with the impedance behavior of the system, particularly the capacitance (C), polarization resistance (R_p) and current density. The presence of pre‐adsorbed Fb had a significant impact on C below approximately −500 mV (increased capacitance). The deviation from ideality of the current response as determined by a KWW empirical dielectric decay function showed significant differences between PBS‐immersed and pre‐adsorbed Fb cases. Earlier, changes in Fb area coverage, height, and eccentricity were observed between voltages lower and higher than 0 mV. The presence of the flat‐band potential around −150 mV as well as high cathodic charge‐transfer reactions taking place below −100 mV relate to these observations. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009