用丝束电极研究SO_4~(2-)对纯铝缝隙腐蚀的影响

采用动电位极化和丝束电极技术测量了纯铝在2mol/L NaCl和2mol/L NaCl 0.8mol/L Na2SO4溶液中的极化曲线、缝隙内外的自腐蚀电位和电化学阻抗分布,研究了SO42-对铝缝隙腐蚀的影响。结果表明,在NaCl溶液中,缝隙内的铝为阳极、缝隙外为阴极;随浸泡时间增加,腐蚀不均匀性增加。加入Na2SO4后,减小了缝隙内外腐蚀电位差,显著降低了铝的腐蚀速度。Na2SO4是中性溶液中铝的吸附型缓蚀剂,延缓了缝隙腐蚀的发生。

A STUDY ON THE EFFECT OF SO_4~(2-) ON CREVICE CORROSION OF PURE ALUMINIUM USING WIRE BEAM ELECTRODE

Polarization curves,corrosion potentials and electrochemical impedance spectroscopy inside and outside the crevice of pure aluminium were measured in 2mol/L NaCl and 2mol/L NaCl 0.8mol/L Na_2SO_4 solutions using potentiodynamic polarization and wire beam electrode techniques.The effect of SO~(2-)_4 on crevice corrosion of pure aluminium was studied.Pure aluminium inside and outside the crevice was anode and cathode respectively in NaCl solution.The distribution of corrosion potentials became inhomogeneous gradually with increase of immersion time.Because of the addition of Na_2SO_4 to NaCl solution,the difference of corrosion potentials inside and outside the crevice decreased and the corrosion rate of pure aluminium was reduced evidently.It was suggested that Na_2SO_4 was an adsorption inhibitor for pure aluminium in neutral solution,and crevice corrosion of the pure aluminum was restrained availably.