电沉积与铁基体电位活化的增强拉曼光谱研究

为探讨电沉积初始过程对电镀层结合强度的影响,采用循环伏安法和表面增强拉曼(SERS)光谱研究了光亮铁电极在5%KCl溶液中表面氧化物随电位负移的还原过程,并应用循环伏安法和恒电流电位-时间法研究了氰化物镀铜体系铁基体的电位活化现象和电沉积初始过程.结果表明,在电位-0.9 V时,特征波数为424 cm-1和499 cm-1的Fe3O4谱峰消失,电位-1.2 V时,特征波数671 cm-1的FeO、谱峰明显降低,说明Fe3O4和FeO在不同电位下依次实现还原过程.循环伏安曲线在-0.9 V及-1.2 V附近也依次出现了铁氧化物的还原电流平阶.在氰化物镀液中,铜的析出电位(约-1.4 V)负于铁表面氧化物的还原电位,电极过程首先实现铁表面氧化物的还原,随后铜沉积在活化的铁基体上.

Study of Potential Activation of Iron Substrate in Electrodeposition by Enhanced Raman Spectroscopy

The reductive process of the oxide on bright iron electrode along with the moving of potential towards negative in 5% KC1 solution were investigated using cyclic voltammetry (CV) and surface-enhanced Raman spectroscopy (SERS), aiming al revealing the effect of the initial electrodeposition process on the bonding strength between the electrodeposited coating and substrate. Thus the potential activation and the initial electrodeposition process of iron substrate in copper cyanide bath were studied based on the measurements of the cyclic voltammetry curves (CV) and potential-time curves (CP) at constant current. The results indicated that the eigenfrequency peak of Fe3O4 at 424 cm-1 and 499 cm-1 disappeared at a potential of -0.9 V, while al a potential of -1.2 V the intensity of the eigenfrequency peak of FeO al 671 cm-1 was considerably decreased, indicating that Fe304 and FeO were deoxidized in turn al different potentials. At the same time, the cyclic voltammetry curves also showed evidence to the deoxidizing of iron oxide in turn around a potential of -0.9 V and -1.2 V, respectively. Since the deposition potential of copper (about -1.4 V) is less than the reduction potential of the oxide on the iron substrate in cyanide solution, the reduction of the oxide on the iron surface was preferentially achieved in the polarization process of the electrode, followed by the deposition of copper on the activated iron substrate.