The use of electrochemical impedance spectroscopy (EIS) for the determination of the protective properties of solvent- and water-based paint systems

The corrosion protection properties of three paint systems were evaluated i n 0.5M NaCl solution using Electrochemical Impedance Spectroscopy (EIS). Th e point systems, a water-based, a solvent-hosed, and a mixture of both, wer e prepared commercially. The EIS measurements on the paint systems were con ducted over a wide range of frequencies as a function of time. Bode, phase angle, and Nyquist plots were obtained showing progressive losses in the re sistance and of the coating increase in coating capacitance with exposure t ime. The gradual shift in the phase angle from capacitance to resistance fo r the water-based system was greater than that observed for the solvent-bas ed system. The corrosion protection properties of the solvent-based point w ere found to he superior to those of the water-based system. Those of the l ayer of the hybrid solvent/water-based paint was found to be moderately bet ter.