Coating Impedance vs Moisture

Typical impedance spectra of a coating during degradation

Low-frequency impedance as a function of exposure time showing three stages of degradation: moisture absorption, incubation, and substrate corrosion

Figure 1

In-Situ Sensor to Detect Moisture Intrusion and Degradation of Coatings, Composites, and Adhesive Bonds, G.D. Davis, C.M. Dacres, and L.A. Krebs, DACCO SCI Inc.