Corrosion Inhibition Performance of Composite Inhibitors for Carbon Steel in Simulated Seawater

Liu, F., 2019. Corrosion inhibition performance of composite inhibitors for carbon steel in simulated seawater. In: Guido-Aldana, P.A. and Mulahasan, S. (eds.), Advances in Water Resources and Exploration. Journal of Coastal Research, Special Issue No. 93, pp. 397–403. Coconut Creek (Florida), ISSN 0749-0208.In this paper, sodium molybdate, sodium tungstate and sodium citrate were selected to compose a series of corrosion inhibitor solutions in different proportions. Their corrosion inhibition effects on standard Q235 carbon steel in simulated seawater were determined by static weightlessness method, polarization curve method and scanning tunneling microscopy (STM), and the corrosion inhibitor formula having better synergistic corrosion inhibition effect with molybdate was determined through experiments. The results show that the concentration of tungstate inhibitor was too high, but the inhibition rate was very low when tungstate and molybdate are combined. When sodium citrate and molybdate were combined and tungstate was added, the corrosion inhibition rate of the composite inhibitor increased obviously, but increased first and then decreased, indicating that there was an optimum ratio between sodium tungstate and sodium citrate, which made the inhibitor have a good synergistic effect. At the same time, it was found that: (1) sodium tungstate is an anodic corrosion inhibitor which mainly inhibits the anodic reaction; (2) when the concentration of composite corrosion inhibitor is more than 300 mg/L, it can protect Q235 carbon steel well, and the lower the temperature of sea water is, the better the protection effect is.