镍基复合镀层在NaCl溶液中的电化学研究

采用体视显微镜、Tafel曲线、电化学阻抗谱和电化学噪声等方法对镀镍层以及复合镀镍层进行了研究.研究发现:镀镍层原有的孔隙在复合镀镍中大部分被惰性微粒封闭;两种镀层的Tafel曲线形状有所不同,复合镀镍层具有更正的腐蚀电位,且腐蚀电流远小于镀镍层;镀镍层的电化学阻抗谱表现为2个时间常数,而复合镀镍层仅为1个,且复合镀镍层的极化电阻约为镀镍层的2倍,表明复合镀镍层的耐蚀性更好,这与电化学噪声的时域分析结果相一致.

Electrochemistry of Composite Nickel Coating in NaCl Solution

Nickel and composite nickel coating are compared by methods of stereomicroscope, Tafel curve,electrochemical impedance spectroscopy(EIS),electrochemical noise,etc.It is found that in the composite coating,most pores originally in nickel coating have been sealed by inert particles;Tafel curves are also somewhat different between the two coatings.The composite coating has more positive corrosion potential and smaller corrosion current than nickel plating.In the Bode plots of nickel-plating,there are two time constants,but only one for the composite coating.The polarization resistance Rp of the composite coating is twice as that of nickel plating.This shows that the composite coating has better corrosion resistance than nickel plating,which is in a good agreement with the time-domain analysis of electrochemical noise.