电沉积金属铬过程中阴极反应机理的研究

A Study on the Mechanism of Cathodic Reaction in Electrodeposition Process of Metallic Chromium

采用电化学阻抗、阴极极化曲线等测试技术，考察了铬酸溶液中金属铬的电沉积过程实验证实了镀铝阴极过程中表面吸附膜的存在，它改变了阴极表面的状态，导致阴极极化曲线上出现电流峰，迫使阴极电位负移，为金属铬的电沉积创造了条件电化学阻抗测量发现，在Ｎｙｑｌｌｉｓｔ图上出现上一个代表吸附膜的“感抗圈”．据此，推导了表面膜电阻的大小，并探讨了Ｈ２ＳＯ４对阴极表面吸附膜电阻大小的影响．

The Electrodeposition process of metallic chromium from chromic acid solution was investigated with the techniques of electrochemical impedance spectroscopy (EIS), polarization curves. The experimental results conform that in the cathodic process of the chromium plating, there exists a surface adsorotion film which changes the cathodic surface condition and causes a current peak appearing on the cathodic polarization curves and forces the cathodic potentials to shift in negative direction. All these result in creation of metal chromium electrodeposition. By measuring the electrochemical impedance spectroscopy of cathodic reaction, it is found that an inductance semi-circle indicating the existence of surface film was appeared in the Nyquist diagram. The resistance of the surface film was measured, and the effect of SO42-ion on the resistance of the surface film was discussed.