The Effect of Different Polyaniiine Types in Silicon Dioxide Containing Coatings for Carbon Steel Protection in Artificial Geothermal Brines

摘要

Carbon steel is prone to uniform and pitting corrosion in geothermal brines,whereas high alloyed materials which exhibit excellent corrosion resistance are relatively costly.For these reasons,coating systems become an alternative to protect carbon steel from corrosion in the geothermal environment.In this research,a coating system consisting of polyaniiine and silicon dioxide was optimized by investigating differently synthesized polyaniiine types in the coating with respect to their protective effect on carbon steel.SEM images of the phosphoric acid and dodecylbenzenesulfonic acid doped polyaniiine showed different morphology,which suggested different physical and chemical properties.The geothermal brine found in Indonesia was simulated by an artificial solution with pH 4.Evaluation of the coating system was performed by surface analysis of the exposed specimens and electrochemical tests,i.e.electrochemical impedance spectroscopy(EIS),open circuit potential(OCP),and potentiodynamic polarization at 150 °C with 1 MPa pressure.Visual assessment of exposed specimens with single component addition into coatings showed that coatings underwent degradation,whereas the combination of polyaniiine and silicon dioxide showed a better protective behavior.