Electrocodeposition of metal and colloidal particle composite films onto a rotating cylinder electrode.

摘要

Metal and colloidal particle composite films have found increasing engineering applications in recent years. Electrocodeposition of such films from an electrolytic dispersion is one method of production with the advantages of speed and better control of the process. The properties of the composite depend greatly on the amount of particles codeposited in the metal matrix. Modeling of the colloidal particle and electroactive species mass transport and their deposition kinetics is done to better understand the effect of system parameters, such as particle size, agitation, and applied current on the rate of particle deposition. The particle deposition kinetic models used are the "Perfect Sink" Model, the Surface Force Boundary Layer Approximation Model, and the Modified Electrode-Ion-Particle Electron Transfer Model. Electrocodeposition onto a rotating cylinder electrode (RCE) system, operated under turbulent conditions, is studied. Theoretical rates of particle deposition, expressed as the particle Sherwood number, is calculated for codeposition in binary and supporting electrolytes. An experimental study on copper and polystyrene particle composite films is performed. The films are formed galvanostatically onto a RCE from an acidic copper sulfate dispersion with sulfuric acid as a supporting electrolyte. The films are studied with a scanning electron microscope (SEM) and the particle deposition rates are obtained from a particle count analysis. The Modified Electrode-Ion-Particle Electron Transfer Model was found to agree with the observed effect of current on the particle Sherwood number, and the general dependency of the RCE rotation speed.