THE STUDY OF INHIBITIVE MECHANISM OF CORROSION INHIBITORS FOR CARBON STEEL IN NATURAL SEAWATER

The inhibitive effect of compound corrosion inhibitor for carbon steel in natural seawater was studied by weight loss method.The inhibitory mechanism was analyzed by polarization curves and EIS.The results showed that the critical concentration was 280mg/L and the inhibitive efficiency was 93.8% without pre-filming process,and local corrosion was not found; the critical concentration was 210mg/L and the inhibitive efficiency was 93.1% with pre-filming process (1000mg/L,48h).The results of polarization curve indicated that the corrosion inhibitor was mixed-type inhibitor,which mainly inhibits anodic reaction.The results of EIS revealed the reaction of this inhibitor was composed of three stages:corrosion inhibitors were adsorbed on electrode surface primarily during initial stage of reaction,and the first inhibitor film was formed until 48h,while the film developed to multilayers during anaphase stage of reaction.