The effect of thiosulfate ion on the corrosion behavior of 310 SS in saturated ammonium chloride and 5 M sodium chloride solutions, with or without the addition of 0.01 M sodium thiosulfate, was investigated. Potentiodynamic polarization curves showed that a delayed pitting corrosion was found in saturated ammonium chloride solution as compared with that in 5 M sodium chloride solution. The addition of 0.01 M sodium thiosulfate to the saturated ammonium chloride solution caused a substantial effect on the electrochemical behavior. At the potential in the range of -0.35 to +0.15 V, both the anodic polarization curves and the microscopic observation indicated that S 2O 3(=) participated in the electrochemical reactions. The anodic current density increase sharply and sulfide was formed on the specimen surface in this potential range. However, once the potential was greater than 0.15 V, the current density decreased and a secondary passive behavior exhibited in the polarization curve. The synergistic effect of Cl - and S 2O 3(=) on pitting corrosion of 310 SS is also discussed.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Science(all)