Electrochemical and physico-chemical characterization of fluorinated organic coatings for steel and concrete protection: influence of the pigment volume concentration

In this paper the electrochemical and physico-chemical characterization of fluorinated coatings was carried out. Their water permeability and its dependence on the pigment volume concentration (PVC) was quantitatively investigated through electrochemical impedance measurements and a linear relationship between the maximum amount of permeated water and the PVC was found. The impedance data analysis, performed through equivalent circuit modelling, on results obtained on undamaged and artificially damaged coatings was used to evaluate the protective performance and the retention of the coating adhesion once exposed to aggressive environments. It demonstrated that these properties are not remarkably affected by the PVC variation, even if the lower the PVC, the higher the performance of the coatings. The influence of the pigment concentration on some physico-chemical properties (water vapour diffusion coefficient, tensile strength, tensile strain and gloss) was also evaluated for the optimization of the coating formulation. (C) 1998 Elsevier Science S.A. All rights reserved.