Improved Electrochemical Test System For Evaluation Disbondment of Organic Coatings

Currently available Electrochemical Impedance Spectroscopy (EIS) Systems cannot be used to measure the degree of corrosion protection afforded by thick, high quality organic coatings. The impedance at which a coated metal\'s behavior switches from capacitive (due to the coating) to resistive (due to coating defects) is indicative of coating quality. Unfortunately, the impedance at which the switch occurs can be as high as 1012 ohius/cmX on a high quality coating. This project will develo^ and demonstrate a prototype EIS system capable of measuring 101 ohio impedances at 1 mHz and a 10 mV AC excLtation voltage. A special low current potentiostat that can measure femtoamp AC currents is the critical portion of the new system.