镀锌钢板墨绿色钝化膜的腐蚀行为

Corrosion behavior of dark green passivation film on galvanized steel sheet

采用极化曲线、电化学阻抗谱和中性盐雾试验,研究了镀锌钢板墨绿色钝化膜的耐蚀性。在质量分数为5%的NaCl溶液中,钝化试样的腐蚀电位较未钝化试样明显正移,腐蚀电流密度大幅降低。镀锌未钝化及钝化试样的Nyquist谱图呈现2个较为完整的容抗弧,说明腐蚀体系受电化学控制。墨绿色钝化试样的容抗弧半径较未钝化试样大,因为钝化膜的形成增大了腐蚀过程的反应电阻,从而提高了试样的耐腐蚀性能。在中性盐雾试验中,镀锌墨绿色钝化试样的耐白锈时间达到400h。

The corrosion resistance of dark green passivation films on zinc-plated steel sheet was studied by polarization curve measurement, electrochemical impedance spectroscopy and neutral salt spray test. The passivated sample features a more positive corrosion potential and much lower corrosion current density as compared to non-passivated sample in 5% （mass fraction） NaCl solution. The Nyquist plots of the samples with and without passivation was characterized as two complete capacitive arcs, indicating that the corrosion is controlled by electrochemical process. The radii of capacitive arcs of the passivated sample are larger than that of non-passivated sample, because the passivation film formed on the surface of sample increases the reaction resistance in corrosion process, thus the corrosion resistance of the sample is improved. The anti-white rust time of the passivation film in neutral salt spray test is 400 h.