Periodic Reverse Current Research Articles

The effect of periodic reverse current on the surface roughness of metal deposits and the maximal deposition rate

The mechanism of electrode surface roughening in metal electrodeposition with a periodic reverse current (RC) is outlined. The relation between the shape of the RC and the maximal deposition rate is shown. Good agreement between the mathematical model, experimental results and literature data is obtained.

Periodic Reverse Current Process in Electroplating Using Acid Copper Electrolytes

SummaryThe effect of periodic reverse current on deposit properties is investigated by varying current parameters and electrolyte composition. Using high reversal frequencies, plating speed, throwing power and surface quality can be increased in comparison with d c plating. By choosing convenient current parameters, the benefit of periodic reverse plating can be considerable.

銅の電解精製における陽極溶解過程について

For the purpose of investigating the mechanism of anodic passivation in the electrolytic refining of copper at high current densities, the polarization curve was determined ly the potential sweep method, while the resistance polarization in the process of anode passivation was measured by the current interrupter method. Also, the polarization in the electrolysis by using periodic reverse current was measured. From these results, the mechanism of anode passivation was discussed.The phenomenon of passivation of copper anode is caused by the abnormal increase of resistance polarization due to the formation of a passive film such as oxide.It is presumed that the anode passivation occurs as a result of arrival to the passivation potential due to the increase of concentration polarization.The reverse current aids rapid disappearance of the concentration gradient in the boundary film on the electrode, from which it is considered that the application of periodic reverse current for electrolytic refining of copper is noticeably effective to prevent the anodes from being passivated.

周期的反転電流による銅の電解精製の工業化試験

Large scale tests on the application of periodic reverse current in electrolytic refining of copper were carried out at the pilot plant of Hitachi Refinery. A thyrister rectifier with an output capacity of D. C. 13, 000A was installed for the tests to generate the periodic reverse current. High current density of 350-400 A/m2 (effective) was applied under normal electrolytic conditions.Under these conditions, an anode passivation and other abnormal phenomenon did not occur and the appearance and deposition of cathode was found to be satisfactory. From the tests, it was confirmed that the technique of periodic reverse current could be applied in the electrolysis in industrial scale.The cathode copper obtained from thses pilot plant tests were melted and casted into wire bars. Any differences in electric conductivity was not found between these wire bars and those of cathode copper obtained from the usual operation under 200-250A/m2 D. C.

シアン化銅メッキ添加剤の光沢効果について

Although the bright and leveled copper deposits from cyanide baths are widely used in practical plating, there have been found less investigations on brightners and their effects of these deposits than those of nickel or acid copper plating deposits. The author has investigated on brightners of copper cyanide baths. In this paper, there are given the results of the brightening effects of copper cyanide baths; the investigations were carried out on the cathodes in Hull cell and Haring cell with about 60 kinds of organic and inorganic compounds as additives and under various plating conditions.The results were summarized as follows.1) The most effective brightners included the compounds containing easily freed sulfur, such as thiocyanide, thiosulfate, xanthogenate, etc. Good results were obtained from the baths containing these compounds over a wide range of cathode current density when agitation and periodic reverse current were applied in the bath of high temperature.2) Among the inorganic compounds containing no sulfur, the compounds consisting of the elements belonging to the IIIB-VIB Groups of Periodic Table had good brightening effects. When their atomic weight was larger, they showed the better effects.3) The organic compounds containing no sulfur had no brightening effects, but the effects were improved in some degree when a large quantity of surface active agent was added.