Recent UK work investigating anti-corrosive organic coatings using the electrochemical noise method (ENM)

The Electrochemical Noise Method (ENM) monitors the small potential and current fluctuations that occur naturally in electrochemical cells. It is the least intrusive of all electrochemical techniques in regular use. This paper reviews recent work using the Electrochemical Noise Method to investigate waterborne and solvent based coating systems. The coating systems were investigated on the substrate both as intact coatings and as scribed coatings. In general, the former has corroborated previous work where Rn values of >1 x 107 ohms/cm2 were indicative of protection. In the scribed work the level of protection afforded at the exposed metal surface by the coating was correlated directly with the Noise Resistance value. Also detached films were examined in a novel test cell that can be used to simulate different conditions. Results show that the ENM has useful applications in the laboratory for monitoring the accelerated testing of coatings and to investigate environmentally-friendly inhibitive pigments. The technique could be adapted for in-situ monitoring of structures in the field and a new experimental technique has been devised to enable measurements to be made on electrically connected substrate areas