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In the hydrometallurgical processing route for primary production of zinc, one of the most significant impurities in terms of cost of processing is iron. In the last two decades, electroplating of steel sheet with alloys such as zinc/iron has seen considerable industrial development. In this process, there is an 'anomalous co-deposition', in which zinc is deposited at a higher rate than iron, even though it is more cathodic in the electrochemical series.In the 1980's research papers reported high current efficiencies for zinc electroplating in the presence of a comparable concentration of iron. It is of interest to the zinc industry to know conditions under which zinc could be electrowon efficiently without prior separation of iron. The chief aim of the current project was to obtain data which would allow evaluation of a zinc electrowinning step carried out in the presence of iron. It was necessary to understand the robustness of such a process towards variations in parameters such as electrolyte composition and purity, temperature, and current density. Means of producing smooth, strippable deposits at high current efficiencies also required evaluation. In order to electrolyse high iron solutions at high current efficiency, it is necessary to introduce a separator into the cell, to prevent cycling of iron oxidation at the anode and reduction at the cathode. The focus of this project was on the cathode process, particularly the determination of factors influencing morphology and current efficiency. Experiments involved modifications of some cells typically used in studies of conventional zinc electrowinning. A range of techniques for morphological studies and for electrochemical tets was evaluated for application to this problem, as well as to studies of conventional zinc electrowinning operations / Doctor of Philosophy (PhD)

In this study, the CVD diamond films were grinded using composite electroplating in-process sharpening (CEPIS). At an applied load of 4.2 kg, a rotation speed of 200 rpm and 20 rpm for the upper and lower spindles, the effects of NiCl2 (nickel chloride) content of electrolyte (in the range of 5-75 g/l) and cathode current density (in the range of 0-7.5 ASD) on the structure of the nickel-diamond composite coating and its grinding ability were investigated. Based on the experiment results, the coating structure became porous and the coating thickness increased with decreasing NiCl2 content of electrolyte during the composite electroplating process. During CEPIS process, the material removal rate of diamond film has no obvious concern with the NiCl2 content at low cathode current density (below 2.5 ASD). However, its material removal rate rapidly increased to a saturated value with increasing NiCl2 content at high cathode current density (above 5 ASD). The NiCl2 content to achieve a saturated material removal rate increased with increasing cathode current density. In this study, the maximum removal rate of diamond film is about 0.093 mg/min at the NiCl2 content of 75 g/l and the cathode current density of 5 ASD.

Thesis (M. Sc. (Physics))--Rhodes University, 2003.

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Thesis (Ph. D.)--University of Wyoming, 2005. / Title from PDF title page (viewed on Nov. 5, 2007). Includes bibliographical references.

Thesis (Ph. D.)--University of Minnesota, 1930. / Vita.

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.