potentiodynamische

Potentiodynamic polarization is an electrochemical method used to study corrosion behavior and electrode kinetics by sweeping the potential of a working electrode relative to a reference electrode while recording the resulting current. It is commonly performed with a three-electrode cell in a suitable electrolyte.

During a potentiodynamic scan, the potential is varied at a controlled rate, typically starting near the open-circuit potential and moving in the anodic direction; cathodic sweeps are also used. The resulting current–potential curve, or polarization curve, provides information on kinetic parameters and corrosion resistance.

From polarization curves one extracts Ecorr (corrosion potential) and iCorr (corrosion current density) as measures of corrosion rate. The anodic branch may show passivation, and the pitting potential Epit indicates susceptibility to localized corrosion. Tafel slopes can be determined to quantify reaction kinetics.

Applications include evaluating corrosivity of environments for metals and coatings, assessing passivation behavior, and screening alloys. It is widely used in materials research and quality control.

Interpreting results requires caution: the measured iCorr depends on scan rate, surface finish, temperature, and electrolyte composition; dynamic sweeping may not reflect long-term corrosion under constant potential. High scan rates can exaggerate corrosion currents; gas evolution may disturb the surface.

Historically, potentiodynamic polarization emerged in the mid-20th century as a practical extension of polarization methods and remains a standard tool alongside other electrochemical techniques.