Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (05): 403-407.doi: 10.3866/PKU.WHXB20030505

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The Spontaneous Passivation of Stainless Steel in Simulated Cooling Water and the Influence of Sulfide

Ge Hong-Hua;Zhou Guo-Ding;Wu Wen-Quan   

  1. Electrochemical Research Group, Shanghai College of Electric Power, Shanghai 200090;College of Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093
  • Received:2002-09-11 Revised:2002-11-04 Published:2003-05-15
  • Contact: Ge Hong-Hua

Abstract: The spontaneous passivation of 316# stainless steel in simulated cooling water is studied by electrochemical impedance spectroscopy, and a suitable model is chosen through fitting. It is shown that the film resistance R2 increases while the value of Y02 , which reflects the film capacitance decreases continuously in the course of immersion of the electrode, but R2 decreases sharply with addition of sulfide. The Mott-Schottky plots show that the donor and accepter densities of the passive films on stainless steel immersed in simulated cooling water for 65 days have the values of 1.47×1020 cm-3 and 2.20×1020 cm-3, respectively, but the values increase to 4.52×1020 cm-3 and 7.02×1020 cm-3 after the addition of 9 mg•L-1 sulfide for 1 h. The polarization curves indicate that the passive current rises in the presence of sulfide.

Key words: Mott-Schottky plot, Electrochemical impedance spectroscopy, Passive film, Stainless steel, Sulfide