在NaHCO_3-NaCl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 ,NO-2 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 ;Cr2 O2 -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 NaHCO_3-NaCl SOLUTION

The effects of anions on the pit nucleation and growth on A3 steel in NaHCO 3-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 MoO 2- 4, indicating suppression of pit nucleation and propagation. Cr 2O 2- 7 anion suppressed pit nucleation but stimulated pit growth. SO 2- 4, NO - 3 anions stimulated both pit nucleation and propagation at low concentrations.The pitting potential and repassivation potential decreased linearly with logarithm of SO 2- 4 concentration. Increasing the concentrations of SO 2- 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.