EIS study of the rust converter effectiveness under different conditions

The present work evaluates the anticorrosive properties of a rust converter applied on pre-rusted steel samples obtained in atmospheres with different aggressiveness. The nature and morphology of oxide/conversion layer are characterised by XRD and SEM techniques. In order to make a comparative study, pre-rusted samples with and without rust converter are painted and the electrochemical behaviour is monitored using EIS technique.The results suggest that the conversion layer generated in non-aggressive media is not efficient and, consequently, the use of the rust converter is not beneficial, or even harmful, on the overall paint behaviour. Nevertheless, when it is applied on samples pre-corroded in aggressive media the formed conversion layer is more compact and the protection properties of the painted samples are clearly improved.