The Study of Copper Anodes in Acid and Cyanide Plating Baths
The 1956 Carl E. Huessner Gold Medal Award was given to Charles Faust and William H Safranek for Best Paper appearing in Plating or the AES Technical Proceedings in 1955, and their paper is republished here in a series on the AES/AESF/NASF Best Paper Awards. Their work involves an evaluation of anodes for copper plating at the time when OFHC anodes were first emerging in use.
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Charles L. Faust & William H. Safranek
Battelle Memorial Institute
Columbus, Ohio, USA.
The 1956 Carl E. Huessner Gold Medal Award for Best Paper appearing in Plating or the AES Technical Proceedings in 1955
Originally published as C.L. Faust and W.H. Safranek, AES 42nd Annual Technical Proceedings, 42, 193-198 (1955)
Editor's Note: This paper is part of a series on the AES/AESF/NASF Best Paper Awards. In 1955, Charles L. Faust and William H. Safranek received the Carl E. Huessner Gold Medal Award for Best Paper appearing in Plating or the AES Technical Proceedings. A printable PDF version is available by clicking HERE.
For several years after high-efficiency copper cyanide baths were introduced, electrolytic copper was preferred for anodes. The electrolytic copper then was the only high-purity metal supplied by reliable sources.
High-purity cast anodes (OFHC) became available about two years ago [~1953], overcoming the disadvantage of the electrolytic copper with respect to fastening hooks. The cast anodes dissolve uniformly, thus, creating less scrap than electrolytic copper. Furthermore, the high-purity cast anodes are supplied in lengths up to 90 inches, whereas electrolytic copper slabs are only 36 inches long. Most anodes used for plating need to be longer than 36 inches.
More than two million pounds of the high-purity castings have been used for copper plating since they were introduced. Several users have reported better results with the new cast form, by comparison with electrolytic copper. Particle roughness has been reduced. As a result, diaphragms have been eliminated in some installations.
The high-purity cast anodes were compared with electrolytic copper and with other types of anodes in laboratory and pilot-plant baths to provide information needed for commercial operation. This report deals with the laboratory and pilot-plant data.
Density and purity of anodes
The density, purity, and grain size of the anodes included in this study are listed in Table 1. The impurity contents given in Table 2 were the basis for calculating the purity, in accordance with the customary procedure for such an estimation.
The oxygen-free anodes and the rolled bars were denser than the electrolytic copper or the conventional castings. The porosity in the electrolytic and the conventional cast copper is associated with irregular dissolution in copper-plating baths, leading to the formation of small anode particles that contribute to "shelf" roughness in copper electroplates.
Table 1 - Density, purity and grain size of copper anodes.