Evaluation of the corrosion protection of steel by anodic processing in metasilicate solution using the scanning vibrating electrode technique

Abstract

Anodic processing in metasilicate solution was investigated for the improvement of the corrosion resis-tance of various steels, namely F111 low alloy carbon and 304 stainless steels, as well as on galvanizedsteel cut edges. The efficiency of the prior electrochemical treatment for each material was tested duringtheir exposure to naturally-aerated aqueous chloride solutions of different aggressiveness. Analysis wasperformed using the scanning vibrating electrode technique (SVET) in order to detect local ionic currentdistributions over the samples under study associated to the corrosion reactions. The onset of corrosionprocesses was greatly inhibited after anodic processing with metasilicate on both the low alloy carbonsteel and the galvanized steel cut edge. Conversely, SVET analysis of unbiased 304 steel samples tested in0.1M chloride-containing solution did not show differences between pristine and metasilicate-treatedsurfaces. Differences intheelectrochemical reactivity between treatedandnon-treated304 steel surfaces were only observed after partial removal of the corresponding passive layers under operator-controlledpolarization