Corrosion Inhibition Mechanism of Molybdate Complex Inhibitor in Sea Water

The corrosion inhibition mechanism of molybdate complex inhibition was studied in sea water by EIS and energy spectra. The results of electrochemical EIS testing showed that the corrosion rate decreased because the complex inhibitor increasing the charge transfer resistance of metal surface. The results of XPS showed that a compact protective passive film was formed on the surface of carbon steel in seawater. The main components of the film are Fe3O4 and Fe2O3 and a little Fe3+, MoO42- and organic substance. X-ray dispersive spectroscopy (EDS) testing showed that the calcium content in the film on carbon steel surface was very low when addintion of the compound inhibitor was only 0.08%, indicating that the complexation and dispersion of organic phosphate (HEDP) and sodium gluconate on Ca2+ in seawater impeded the deposition of calcium on metal surface. It also showed that the complex corrosion inhibitor had good scale inhibition performance.