Using an accurate thin-layer cell, the electrochemical impedance corresponding to the diffusion of ferro-cyanide ions was measured on a large-disk electrode covered by thin films of electrolyte. Experimental
impedance diagrams obtained in a large frequency range (100 kHz−5 mHz) were in good agreement with
those expected in the case of a spatially restricted linear diffusion impedance. For electrolyte film thicknesses
lower than 100 μm, an increase of the low-frequency limit of the real part of the impedance and a decrease
of the high-frequency phase angle were however observed experimentally as the electrolyte film thickness
decreases. This specific behavior, in disagreement with the classical linear diffusion theory, was explained
by the potential distribution existing in the thin-layer cell and was modeled using an original transmission
line. In a very low-frequency range (lower than 1 mHz), an additional time constant was also evidenced. In
consistency with previous work of Gabrielli et al. on microelectrodes, this feature was ascribed to the radial
contribution of diffusion processes existing within a thin-layer cell.
In this work, the effect of the nature of the salt anion (chloride and sulphate) in the Cu–Zn citrate bath was investigated, using cyclic voltammetry (CV) and chronoamperometry (CA). Experimental electrodeposition parameters (switching potential and imposed potential) were varied in order to examine their influence on the deposits. The coating microstructures were observed by scanning electron microscope (SEM-EDS), the coating phases were characterized by X-ray diffraction (XRD) analysis and the surface composition was assessed by XPS. Higher current efficiency was obtained in chloride baths compared to sulphate baths and best deposits were obtained at
compared to
and
. Corrosion test results in 0.5 M NaCl solution show that Cu–Zn deposit produced from chloride bath exhibited the highest corrosion resistance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.