A coating health monitor (CHM) is based on electrochemical impedance spectroscopy (EIS). It consists
of a mini-potentiostat coupled to electrodes mounted on top of a paint coating. It is periodically
interrogated by a laptop so an inspector can assess the paint’s condition and determine if detailed
inspection or maintenance is needed. The units are battery powered with an estimated battery lifetime of
up to ten years, depending on the frequency of measurement and interrogation. CHMs can be
strategically placed in areas difficult to access, monitor, and maintain. These wireless units can be read
up to 500 feet away by a laptop that displays the current coating condition. Benefits include increased
readiness and safety and reduced inspection costs.
Several panels with different paint coatings were tested in the laboratory. Accelerated corrosion
exposure was achieved with alternate immersion. EIS measurements for the CHM and a commercial
potentiostat exhibit excellent agreement over six orders of magnitude. The good coatings exhibit high
electrochemical impedance with very little change during testing. No corrosion was seen after 90 days.
In contrast, although poor coatings exhibited high initial impedance, their impedance had dropped by
several orders of magnitude by the first measurement period and rust quickly appeared.