Laboratory Corrosion Monitoring of Zinc-Rich Paint Coatings on Naval Steel in Seawater by Electrochemical Methods

摘要

Laboratory assessment of the performance of zinc-rich paint (ZRP) coatings on naval steel in seawater has been carried out using electrochemical impedance spectroscopy (EIS) combined with cathodic protection potential measurements. Different formulations of painted naval steel samples were investigated during exposure times up to 50 days. ZRP coating formulations included those with the zinc pigment content covering a wide w/w-concentration range as well as those with different organic/inorganic binders based on chlorinated-rubber, epoxy-polyamide, ethyl-silicate and alkyd-resins. Experimental impedance diagrams ahve been quantitatively explained in terms of a transfer function analysis using identification procedures and non-linear fit routines. Information concerning the influence of both binder type and zinc pigment concentration on the corrosion protection behaviour of these ZRP coatings was obtained from the exposure time dependence of the system parameters, which were derived from the fitting procedure.