Some Aspects of the Growth of Electrodeposits

Abstract

The relevance of the processes of crystal growth at a cathode to the development of industrial plating processes is discussed. The published literature on the subject is reviewed with the purpose of emphasising that deposition of metal at a cathode can take place by mechanisms analagous to those observed in other methods of growing crystals. A method of observing and photographically recording the electrodeposition process at high optical magnifications is described. Some results obtained by this method during an investigation of copper deposition, from acid copper sulphate solutions, on single crystal and polycrystalline cathodes are reported. These results illustrate growth by the spreading of layers and the formation of crystallographically well-defined surface features, details of which are dependent on the crystallographic orientation of the cathode surface. Observations of growth by the self-propagating spiral step mechanism are also reported. A cine-recording of these growth processes is available on loan from the authors.