Application of voltammetry to copper electrodeposition
"A study was undertaken to determine the feasibility of using voltammetry and scanning electron microscopy techniques to characterize copper deposition from an acid-sulfate electrolyte. The main process variables investigated were temperature and addition agents (chloride ion, glue, separan or thiourea) at different concentrations, over a range of current densities. Cathodes employed were either polycrystalline titanium or copper. Some long-time copper deposits were also made using Ti cathodes and the orientations of these deposits were determined by x-ray diffraction. Observations of copper crystals produced during voltammetry scans, on a Ti cathode, indicated that a characteristic morphology was associated with each type of addition agent. Temperature also affected the physical appearance of the deposited copper. With a Cu cathode the crystal morphologies were essentially identical, regardless of the addition agent used. At a constant scanning rate of 1 mV/sec, the various addition agents, on both Ti and Cu cathodes, gave characteristic and reproducible voltammograms. Shifts and relative differences between the polarization curves were also noted with changing temperature. The results of this investigation indicate that there is a definite correlation between type and concentration of addition agent and voltammogram. The substrate used in the deposition process also has an effect. A definite relationship exists between the morphology of the copper and the processing conditions used during deposition. It thus seems that a combination of voltammetry and scanning electron microscopy would be potentially useful in predicting the electrolyzability of commercial copper refining or winning solutions"--Abstract, pages iv-v.
Missouri University of Science and Technology
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