Evaluation of the surface treatment effect on the corrosion performance of paint coated carbon steel

D.M. SANTÁGATA; P.R. SERÉ; C.I. ELSNER; A.R. DI SARLI

PROGRESS IN ORGANIC COATINGS

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 1998 vol. 33 p. 44 - 54

0300-9440

Electrochemical impedance spectroscopy studies carried out for plasticized chlorinated rubber coated carbon steel sheets under free corrosion conditions when exposed to artificial seawater. Four different samples types were used (sandblasted, pickled, pickled + phosphatized and sandblasted + wash primer). Electrochemical impedance spectroscopy (EIS) data was interpreted considering the values of the distinct equivalent electrical circuit models, whose components allowed a quantitative evaluation of the long term corrosion behavior for the different pretreated coated steel specimens. Furthermore, from impedance data, the water content of the paint on the steel substrate was calculated by the Basher expression and the progress of the coating delamination process was calculated by an empirical expression relating to the measured/specific double layer capacitance ratio. On the basis of both the experimental and the visually monitored test results it was concluded that the best corrosion performance was provided by pickled + phosphated painted steel surfaces followed by the pickled surface. This result was attributed to the fact that such surface treatment might improve the barrier protection and the steel/paint adhesion properties or reduce the osmotic pressure effect, respectively.