Under Ultrasonic Reaction Control On Copper Electrochemical Deposition Process

The effects of ultrasound on copper electrodeposition in control of heterogeneous electron transfer reaction were investigated with electrochemical impedance spectroscopy and polarization curve. The effects of ultrasound on surface morphology and crystal orientation of copper electrodeposition were investigated with scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis.1.Electrochemical impedance spectroscopy for copper electrodeposition in different ultrasonic conditionsElectrochemical impedance spectrum for copper electrodeposition were recorded in silent and sonicated conditions. The working electrode was a copper plate (5.0mm×5.0mm). The reference electrode was a saturated Hg/Hg2SO4 electrode and a copper plate (10.0mm×10.0mm) was used as counter electrode. The obtained results indicate the following:At the potential of -0.4V (vs. Hg/Hg2SO4), the copper electrodeposition process is in control of heterogeneous electron transfer reaction. In silent condition, the charge transfer resistance is 62.05?. Ultrasound can accelerate the charge transfer rate between the copper electrode and the solution. The charge transfer rate increases with increasing ultrasonic power. In sonicated condition (24kHz), the charge transfer resistance decreases from 42.89? to 28.12? with increasing ultrasonic power from 220W to 440W. The charge transfer rate rate increases with decreasing ultrasounic frequency. In sonicated condition (440W), The charge transfer resistance decreases from 40.71? to 28.12? with the decreasing ultrasonic frequency from 76kHz to 24kHz.2. Effects of ultrasound on kinetic parameters of copper electrodepositionEffects of ultrasound on kinetic parameters of copper electrodeposition reaction in CuSO4 solution were investigated with polarization curve. The working electrode was a copper plate (5.0mm×5.0mm). The reference electrode was a saturated Hg/Hg2SO4 electrode and a copper plate (10.0mm×10.0mm) was used as counter electrode. The scan rate was 1mV·s-1. The results indicate that:Ultrasound can increase the exchanging current density of copper electrodeposition. At the constant temperature, ultrasonic frequency and Cu2+ concentration, the exchanging current density and the ratio of the exchanging current density with ultrasound to that without ultrasound increases with the increasing ultrasonic power; At the constant temperature, ultrasonic power and Cu2+ concentration, the exchanging current density and the ratio of the exchanging current density with ultrasound to that without ultrasound increase with the decreasing ultrasonic frequency; At the constant ultrasonic frequency, ultrasonic power and Cu2+ concentration, the exchanging current density increases with the increasing temperature but the ratio of the exchanging current density with ultrasound to that without ultrasound decreases with increasing temperature.Ultrasound has almost no effect on the charge transfer coefficient. The electrochemical reaction mechanism of copper electrodeposition is not changed by ultrasound. 3. Effects of ultrasound on surface morphology and crystal orientation of copper electrodepositionEffects of ultrasound on surface morphology and crystal orientation of copper electrodeposition were studied with scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The working electrode was a copper plate (10.0mm×10.0mm ). The reference electrode was a saturated Hg/Hg2SO4 electrode and a copper plate (15.0mm×10.0mm) was used as counter electrode. The results indicate that: Ultrasound has no obvious effect on the morphology or crystal orientation of copper electrodeposition prepared in control of heterogeneous electron transfer reaction. (220) is the preferred orientation both in silent and sonicated conditions.Ultrasound has an obvious improving effect on copper electrodeposition obtained in control of mass transport, ultrasound makes the grains fine on deposit surface. Ultrasound obviously affects the texture coefficient of copper deposition. (111) is the preferred orientation in silent condition, but in sonicated condition (220) is the preferred orientation.