化学镀Ni-Cu-P合金镀层耐蚀性研究

A Study on Corrosion Resistance of Electroless Plated Ni-Cu-P Coating

采用极化曲线和交流阻抗法,与Ni-P合金镀层对比,研究了化学镀Ni-Cu-P合金镀层在3.5%NaCl水溶液中的电化学行为。极化曲线结果表明,化学镀Ni-Cu-P合金镀层的自腐蚀电流密度(4.037μA/cm2)远远小于Ni-P合金镀层,说明Ni-Cu-P合金镀层的耐蚀性能比Ni-P合金镀层好。在交流阻抗谱图中,化学镀Ni-Cu-P合金镀层在整个浸泡过程中仅出现一个时间常数的单容抗弧,镀层电阻不断的增大,表明镀层有钝化膜不断生成。

Electrochemical behavior of electroless plated Ni-Cu-P coating in 3.5% NaCl aqueous solution was studied using methods of polarization curve and electrochemical impedance. The results were compared with those of electroless plated Ni-P coating. The results of polarization curve measurement show that self-corrosion current density of the Ni-Cu-P coating （4. 037 μA/ cm^2） is much less than that of the Ni-P coating suggesting corrosion resistance of the Ni-Cu-P coating being better than that of the Ni-P coating. During the dipping corrosion process, only a single capacitance loop with one time constant appear on the electrochemical impedance spectra of the Ni-Cu-P coating and the resistance of the coating keeps increasing. These show that a passivation film is present on the Ni-Cu-P coating surface and the passivation film is growing continuously.