用丝束电极研究亚硝酸钠对低碳钢缝隙腐蚀的影响

在5％NaCl溶液和5％NaCl＋5％NaNO2溶液中，采用丝束电极技术测量了低砖、钢缝隙内、外的自腐蚀电位和电化学阻抗谱，研究了亚硝酸钠对低碳钢缝隙腐蚀的影响．结果表明，在5％NaCl溶液中，缝隙内的碳钢为阳极、缝隙外为阴极；随浸泡时间增加，腐蚀不均匀性增加．加入5％NaNO2后，缝隙内外的腐蚀电位都正移，电位差减小，碳钢的腐蚀速度显著降低．亚硝酸钠使碳钢表面形成致密氧化膜，有效抑制了碳钢的缝隙腐蚀．

Effect of Sodium Nitrite on Crevice Corrosion of Mild Steel Using Wire Beam Electrode

The effect of sodium nitrite on the crevice corrosion of mild steel was studied by applying the wire beam electrode technique.The corrosion potentials and the electrochemical impedance spectra inside and outside the crevice were measured in 5%NaCl and 5%NaCl+5%NaNO2 solution.Experimental results showed that the mild steel inside the crevice was anode and that outside the crevice was cathode in 5%NaCl solution.The distribution of the corrosion potentials became inhomogeneous gradually with the increase of immersion time.Because of the addition of 5%NaNO_2 solution,the corrosion potentials inside and outside the crevice shifted towards positive,the difference of corrosion potentials was diminished and the corrosion rate of mild steel was reduced evidently.In 5%NaCl+5%NaNO_2 solution,compact oxide film with a strong adhesion to the surface of the mild steel was formed,and the crevice corrosion of the mild steel was effectively restrained.