Evaluation of the protection against corrosion of a thick polyurethane film by electrochemical noise

This paper focuses on the study of protection against corrosion by means of a thick polyurethane film. Noise resistance, R,, calculated from a series of potential and current noise measurements, shows that electrochemical noi se (EN) technique was able to monitor corrosion under coated metals even wh en applied at high thicknesses. By using spectral analysis, the nature of t he attack on the metallic surface was determined; indeed, the characteristi cs of the corrosion process were determined even from the beginning of the phenomenon when the surface was exposed in a Salt Fog Chamber. It was possi ble to determine both how the continuous protection was given by the polyur ethane film as a barrier and when the corrosion process was controlled by t he appearance of pores on the barrier film. This paper seeks to establish a methodology to study highly resistant coatings. (C) 2001 Elsevier Science B.V. All rights reserved.