Electrochemical monitoring of organic coating degradation during atmospheric or vapor phase exposure

This article reports an atmospheric electrochemical monitor (ATMEIS) designed to assess degradation of painted metal substrates during atmospheric exposure using electrochemical impedance spectroscopy (EIS). The monitor consists of a painted steel coupon upon which a gold electrode is electron-beam-deposited to serve as a reference/counter electrode. Electrochemical impedance spectroscopy measurements were made between the underlying steel substrate and the gold reference/counter electrode residing on the coating surface. The ATMEIS has been tested in both immersion exposure and in an atmospheric exposure chamber and has been found to generate EIS data consistent with that predicted for a painted metal coupon in an aggressive environment. Details of the design and testing of this monitor are reported herein.