Sensing corrosion within an artificial defect in organic coating using SECM

The electrochemical reactivity of a defect in organic coating was investigated by electrochemical noise (EN) and scanning electrochemical microscopy (SECM). Time dependent EN spectra and SECM image on a metal with defective organic coating was measured, and corresponding EN frequency domain spectra and probe approach curves (PACs) were used to obtain electrochemical reactivity information within the coating defects. All time domain and frequency domain analyses, and SECM measurements were successful indicators of corrosion intensity within the defect. The amplitude of electrochemical current noise (ECN) and the low-frequency plateau of the power spectral density (PSD) WL increased significantly with corrosion intensity.