在NaHCO3-NaCI体系中阴离子对低碳钢点蚀的抑制作用

采用动电位和恒电位技术研究了低碳钢在NaHCO3-NaCl体系中的点蚀电位和再钝化电位的分布以及5种阴离子对它们的影响.结果表明，点蚀电位和再钝化电位均服从正态分布；在5种阴离子中，NO2-和MoO2-4能够抑制点蚀的发生和发展，而SO2-4、NO-3在低浓度时降低点蚀电位和再钝化电位，促进点蚀的发生，在高浓度时能够破坏自钝化；Cr2O2-7能显著抑制点蚀的发生，然而点蚀一旦产生后它却能加速点蚀的发展.

EFFECT OF ANIONS ON PITTING CORROSION OF A3 STEEL IN NaHCO3- NaCI SOLUTION

The effects of anions on the pit nucleation and growth on A3steel in NaHCO3 - NaCl solutions were investigated by potentiodynamic and potentiostatic techniques. Pitting potential and repassivation potential were shifted towards positive direction by the addition of NO-2 and MoO2-4, indicating suppression of pit nucleation and propagation. Cr2O2-7 anion suppressed pit nucleation but stimulated pit growth. SO2-4, NO-3 anions stimulated both pit nucleation and propagation at low concentrations. The pitting potential and repassivation potential decreased linearly with logarithm of SO2-4 concentration. Increasing the concentrations of SO2-4, NO-3 over 0.02M changed the potential from passive to active region. Pitting potential and repassivation potential of carbon steel were found to obey normal distributions.