Technology Of Colored Electroplating On Nickel Substrate

The silver-white Ni surface is not attractive. Cuprous oxide(Cu2O) is usually usedas special functional material. The Cu2O films on the metals surfaces show a variety ofcolors with nanoscale thickness of the films, such as gold, green, blue, red, purple andso on due to the optical interference effect. The Ni surfaces can be decoreted byelectroplating colored Cu2O films to improve business value. In this study, thetechnological conditions of electroplating colored Cu2O films were studied.Cyclic voltammetry was used to study the reaction mechanism in the basic platingbath. X-ray photoelectron spectroscopy(XPS) was used to detect elements compositionand valence state and the result indicates the color coatings mainly consist of Cu2O.Scanning electron microscopy(SEM) was used to detect surface morphology of thecolored coatings and the SEM photographs show the smooth surface of Cu2O filmswithout special features.Hull cell was applied to research the suitable electroplating conditions by usingdirect and puls current. The direct current Hull cell experiment with constant charge wascarried on to study technological conditions including temperature,current density andadditives. The opitimized conditions of direct current Hull cell experiments are35°C,0.375mA·cm-2and20g·L-1potassium sodium tartrate. The pulse plating conditionsincluding peak current, duty cycle and additives were studied by Hull cell experiment.The opitimized conditions of pulse current Hull cell experiments are35.0°C, ton=0.05s,toff=1.5s and ip=10~20mA·cm-2, and the quality of colored film is not improved byadditives。Electroplating experiments were carried on by the opitimized conditions, whichindicates the colors of coatings appears cyclically with addition of thickness of coatings.And Ellipsometry was used to characterize the thickness of Cu2O films plated withdifferent time under the same plating conditions. The results show linear relationshipbetween thickness of Cu2O films and plating time, which means the nanoscale thicknessof the film, which correlated to the color, was varied by changing the deposition time.