The term electrochemical noise is used at corrosion studies to describe the nucleation processes and their healing. These processes correlate to small electrically measurable pulses (events). The analysis methods used are, e.g. event counting, standard deviation or evaluation in the frequency range.
The special feature of measuring electrochemical noise compared to other methods of electrochemical corrosion testing is that the gain in information can be obtained without external excitation of the system (potential noise). The high sensitivity of the test method enables, e.g., the initiation processes of local corrosion phenomena on passive metal surfaces to be determined.
Causes of the electrochemical noise on passive metals are activation and re-passivation processes of the passive layer respectively the hereby caused fluctuations of the charge at the phase boundary interface metal-(passive layer) / electrolyte. Depending on the experimental setup, these charge fluctuations can be measured as noise of current or potential.