HYDRODYNAMIC EFFECTS OF HYDROPHILIC ALCONOX SURFACTANT ON THE MACROMORPHOLOGY OF ELECTRODEPOSITED ZINC AND FLOW VISUALIZATION

The macromorphological properties of electrodeposited zinc that result from hydrodynamic flow conditions on a rotating-disk electrode (RDE) and along a flat plate electrode (FPE) embedded in a channel flow cell (the mutual effects of the flow and electric fields and the interfaci al tension change imposed by the adsorption of a moderately strong com mercial (Alconox) surfactant) have been investigated using acidic zinc chloride solutions in the current density range 10-50 mA cm(-2). All the complex hydrodynamic characteristics of the re-attaching flow and the presence of streamwise-directed counter-rotating Taylor vortices b ehind the stagnation point and separation, together with stabilized st ream features in an admixture of Liqui-Nox surfactant, are clearly del ineated by the macromorphology of three-dimensional relief imprints. T he macromorphological properties of relief striations in zinc electrod eposition mainly represent the competition between the flow and electr ic fields and depend on the average current density, the rotation spee d (RDE) and/or the linear flow velocity (FPE), the time of deposition, the ionic zinc content, the electrolyte composition, the pH value, th e hydrodynamic flow pattern and the hydrodynamic effects of surfactant s. The last of these is reflected in both the stabilization of systema tic disturbances and perturbations within the boundary layer, and the interfacial surface tension traction (the flow-field throw). The macro morphological imprints of electrodeposited zinc within a certain curre nt density range could be employed for both the instantaneous and cumu lative (time sequence of photoimprints) electrochemical visualization method. The hydrodynamic effect of Alconox surfactant has been compare d with contributions from stronger (DuPont fluorosurfactant) and weake r (glycerol) surface-active agents, as well as with the macromorpholog ical features obtained in surfactant-free zinc chloride solutions unde r the same electrodeposition conditions. The hydrophilic wetting effec t of Liqui-Nox surfactant on the macromorphology of zinc deposits is e mphasized.