Cyclic Polarization Purpose

The Cyclic Polarization technique is normally used to qualitatively evaluate a metal’s tendency to pit in a corrosive environment. With this technique, you can determine quantitative information such as protection potential (Eprot), pitting or breakdown potential (Ep or Eb), and passive current (ip). The experiment is based on a slow linear sweep of the potential of a metal. The initial sweep is towards anodic potentials. When the measured current reaches a specified level, the sweep direction is reversed and a cathodic-going sweep occurs. The experiment’s data are a plot of log(current) versus potential. Both forward and reverse sweeps are shown on one plot. Significant hysteresis between the sweeps indicates pit formation.

See ASTM Standard G-61, “Standard Test Method for Conducting Cyclic Polarization Measurements for Localized Corrosion Susceptibility of Iron-, Nickel- or Cobalt-Based Alloys ” for useful information about Cyclic Polarization measurements.