高脉冲频率对纳米晶镍-铁合金电沉积层性能的影响

Effect of Pulse Frequency on Performance of Electroplated Nanocrystalline Ni-Fe Alloy Coatings

为了探讨不同高脉冲频率对Ni-Fe合金镀层性能的影响,在铜锌合金基体上脉冲电沉积了纳米晶Ni-Fe合金层。采用SEM对纳米晶Ni-Fe合金镀层的显微形貌进行了观察,采用XRD对镀层的晶粒尺寸进行了表征,利用2273电化学工作站对其在3.5%NaCl溶液中的动电位极化曲线和交流阻抗谱进行了测试,研究了其耐蚀性能。结果表明:纳米晶Ni-Fe合金镀层致密、均匀;脉冲频率从0.5 kHz逐渐增至3.5 kHz时,镀层中的Fe含量在14.17%～22.77%内呈非线性变化,晶粒尺寸从23 nm逐渐降至15 nm;纳米晶Ni-Fe合金镀层的耐蚀性能呈下凹曲线规律变化,在1.5～2.5 kHz内耐蚀性能较好,1.5 kHz时最佳,自腐蚀电流密度约为0.216μA/cm2,镀层电阻约为1.443×105Ω.cm2。

Nanocrystalline Ni-Fe alloy coatings were prepared on Cu-Zn alloy substrate by pulse electroplating.The morphology of as-prepared Ni-Fe alloy coatings was observed using a scanning electron microscope,and the grain size of the alloy coatings was analyzed by means of X-ray diffraction.Moreover,the anodic polarization curves and electrochemical impedance spectra of the alloy coatings in 3.5% NaCl solution were measured with an electrochemical work station so as to evaluate their corrosion resistance.It was found that Ni-Fe alloy coatings obtained under different pulse frequencies were uniform and compact.With the increase of pulse frequency from 0.5 kHz to 3.5 kHz,the Fe content of the coatings varied nonlinearly between 14.17% and 22.77%,and the grain size decreased gradually from 23 nm to 15 nm.In the meantime,the corrosion resistance of the alloy coatings tended to vary in a notch-like mode,and the alloy coatings obtained at pulse frequencies of 1.5~2.5 kHz showed good corrosion resistance.Particularly,Ni-Fe alloy coating prepared at a pulse frequency of 1.5 kHz exhibited the best corrosion resistance,with a corrosion current density of about 0.216 μA/cm2 and polarization resistance of about 1.443×105 Ω·cm2.