Z.H. Gu

A statistical analysis of the electrodeposition of nickel in the presence of a magnetic field

Statistical analysis has been applied to study the effect of magnetic fields on the electrodeposition of nickel in terms of (i) fractional Brownian theory applied to its rate, and (ii) a variance-based analysis of the deposit surface roughness determined by confocal scanning laser beam microscopy.

Electrolytic mass transport at a rotating outer cylinder electrode with developing axial flow in the annulus

Mass transport in an experimental horizontal electrochemical reactor with a rotating outer cylinder and axial flow in the annulus has been investigated, and appropriate dimensionless relationships for the estimation of mass transport rates have been developed by employing statistical regression analysis of experimentally measured flow rates and current density.

Comparison of dynamic behaviour of the anodic dissolution of copper in aqueous chloride and bromide solutions

Abstract Differences in the dynamic behaviour of the anodic dissolution of copper in aqueous NaCl and NaBr solutions containing SCN − ions were studied. In a neutral solution, addition of small amounts of NaBr to relatively concentrated NaCl solutions modifies oscillation amplitude, frequency and mean current density. While the mean value of the anodic current density is essentially the same in 0.5 mol dm −3 NaCl and 0.5 mol dm −3 NaBr electrolytes containing 0.5 mol dm −3 sulfuric acid, fluctuation patterns are different. The experimental results are interpreted via Fractional Brownian Motion theory and analyzed by the principles of chemical equilibria.

Effect of operating conditions on anode passivation in the electrorefining of copper

The effect of various process variables on anode passivation in copper electrorefining was investigated by combining conventional electrochemical techniques, laser-based visualization, and digital image processing in a laboratory scale copper electrorefining cell. High current density operation causes early anode passivation; in the range of 0.23 to 1.50 kA m−2, the effect of current density on the onset of passivation was found to be constant. The higher the temperature the longer the time required for the onset of anode passivation. When the electrolyte is circulated, anode passivation occurs earlier than in the absence of circulation, but the effect also depends on the direction of circulation.

An experimental study of anodic dissolution of copper in aqueous sodium chloride via laser-induced image processing

The formation of a Cu2O precipitate induced via anodic copper dissolution in an aqueous sodium chloride electrolyte was studied over the pH range 1–7 by means of laser illumination and digital processing of video images. A mechanism of precipitation is proposed on the basis of the experimental findings and the theory of ionic equilibria.

A study of anodic slime behaviour in the electrorefining of copper

Abstract The kinetics of anode slime formation and propagation were studied in a laboratory-scale copper electrorefining apparatus. Laser-based illumination and digital image processing of videotaped records of slime movement, combined with current/time monitoring and polarization experiments, provide quantitative information about the complex interaction between characteristic parameters of the copper electrorefining process.

Laser-assisted electrochemical deposition on certain cathodes

Abstract Irradiation by multi-line average-power argon laser was used for the enhancement of the electrochemical deposition of gold and copper from cyanide solution, and copper and nickel from sulfate solutions. The deposition rate was significantly increased with increasing laser power. The diameter of the laser focus on the cathode was less than 30 μm at a power density (intensity) of 0.1 MW/cm 2 . The increase in deposition rate may be explained by thermal activation of the cathode/electrolyte surface at the interface.

On two control parameters of the dynamics of the anodic dissolution of copper

Abstract An experimental study of the effect of SCN − ion concentration and laser bombardment intensity on the anodic dissolution of copper into an aqueous NaCl electrolyte is reported. The laser was used to accelerate the dissolution process. The results are analyzed in terms of power spectra, fractional Brownian motion theory and confocal image processing. An interpretation of the dynamic phenomena via the theory of nonlinear dynamics is also suggested.

Current behaviour under periodic excitation during the anodic dissolution of copper

Current oscillations observed during the anodic dissolution of copper under sinusoidal and square wave potential perturbations are analysed via certain techniques of nonlinear dynamics. Low order Fourier expansions, and Poincaré maps indicate the existence of essentially nonchaotic characteristic structures.

The effect of incident power density on laser-catalyzed oscillatory anodic dissolution

Abstract The effect of laser bombardment on the anodic dissolution of copper into aqueous KSCN NaCl solutions was studied. The experimental results demonstrate that laser bombardment has a significant effect on various aspects of the oscillatory behaviour and the anodic surface, as a function of its power density. It appears that laser imposition can act as an important parameter for the control of the anodic dissolution processes.