为验证某电站闭式循环冷却水系统中的Fe2+含量显著增加是否由低浓度的污染离子NO2－引起, 采用静态挂片失重法、旋转挂片失重法和电化学方法评估了低浓度亚硝酸盐对碳钢材料的腐蚀影响。结果表明, 室温条件下, 在pH为10.0左右的除氧LiOH溶液中, 添加3 mg·kg-1 NaNO2使A106B碳钢的平均腐蚀速率从0.66 μm·a-1增大至0.99 μm·a-1, 但当空气漏入时A106B碳钢的平均腐蚀速率为73 μm·a-1。对比空气溶解引起水样碳酸化对腐蚀的影响, 低浓度NO2－的影响基本可以忽略。

In order to test and verify whether the significantly increased iron concentration in a plant closed cooling water system was caused by the low concentration contamination of nitrite ion, the effect of nitrite on corrosion rate of A106B carbon steel was investigated by static weight loss, dynamic weight loss and electrochemical measurements. The results show that the corrosion rate of A106B steel was increased from 0.66 μm·a-1 to 0.99 μm·a-1 in the deaerated LiOH solution with pH value of 10.0 at a dosage of 3 mg·kg-1 NaNO2, however, the corrosion rate significantly increased to 73 μm·a-1 in the case of air inleakage because of the carbonation. As compared with the effect of dissolved oxygen and carbon dioxide, the effect of low concentration nitrite on the corrosion of carbon steel could be ignored.