Influence of Organic Corrosion Inhibitor on Corrosion Behavior of St-37 Carbon Steel in NaCl Medium

摘要

Good mechanical materials made them to have limitless applications. In order to minimize corrosion rate, corrosion inhibitors are used in Na-Cl medium process. This research was conducted as an attempt to investigate the influence of some organic inhibitors with various concentrations on corrosion behaviour of St-37 carbon steel in NaCl medium. This research used organic corrosion inhibitors pectin and tannin extract. The concentration of the extract which were used ranged from 1% to 12%. The method used was potentiodynamic to observe the value of the corrosion current for four days. Corrosive medium used in this research was NaCl 5%. The results show that the greatest corrosion rate was resulted in the corrosive medium without the addition of inhibitors, while the corrosion rate decreases with the addition of inhibitors. It is also proven from the results of the Tafel plot that shows the decrese of Icor. The greater the concentration of inhibitor that is used, the lower the corrosion rate. The greatest efficiency values both for medium corrosive obtained at inhibitor concentrations of 12% in NaCl 5%. This shows that tannin extract inhibitor is very efficient in controlling the rate of corrosion in NaCl medium. The optical photograph analysed on the morphology of St-37 steel showed that the addition of tanin extract gets less corrosion..