AbstractsChemistry

Electrodeposition of metals may be divided into four categories. In electroplating, articles are coated with a layer of metal for the purpose of ornament or protection. The physical form of the deposit is of prime importance since upon it depend such properties as lustre, hardness and ductility. Good adherence of the deposit to the plated article is also a requisite. The process of electroforming is the production or reproduction of articles by electrodeposition. Reproduction of printing plates and phonograph matrices are common examples of electroforming. In electrorefining, the anodes consist principally of the metal to be refined. The purpose is to convert an impure into a pure metal as, for example, with copper. Except for marked roughness which may cause short circuits and thus lower current efficiency the structure and physical properties of deposits are of minor importance. The process of electrowinning employs insoluble anodes in a solution derived by leaching ores. The purpose is to recover a pure metal from a solution which usually contains other metals. As in electrorefining, the physical structure of the deposit is of small importance since the metal in both cases is usually re-cast from a melt before use. Also, since the deposit is stripped from the cathode starting sheet, the adhesion in both cases must be of a limited degree.[...]