Electrochemical Studies on Inorganic Zero VOC Coated Steel in Atmospheric Exposure and REAP Test

Abstract

The application of coatings for control of degradation of materials has been historically used since ancient civilizations, but usually the coating systems take a long time to show the physical evidence of corrosion on coated metals, so the evaluation of coatings in aggressive atmospheres and with a rapid way has been the dream of the experts and users through the time. Laboratory standard tests have been developed as a quality control for coatings, including salt fog, climate chamber or artificially damaged conditions.The paint systems utilized for the study were zero volatile organic solvents or paints water base with metallic zinc content. The electrochemical measurements were made before and after the potentiostatic test using the electrochemical techniques of Corrosion Potential (Ecorr), Linear Polarization Resistance (LPR), Electrochemical Impedance Spectroscopy (EIS) and the Polarization Curves.For the evaluation of the coatings exposed to the atmosphere, the samples were retired at different times to apply the electrochemical tests in the laboratory and then returned to the exposure rack. For the application of the Rapid Electrochemical Assessment of Paints (REAP), the galvanic current was registered during the potentiostatic conditions due that provides an alternative method for the qualification of paint systems, while the parameter of degradability for the paint systems can be calculated from the LPR results that are showed and compared with the results from both evaluation methods.