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Gold deposits from a pyrophosphate bath and those from a cyanide bath, have been compared in physical properpies and crystal structure to assess functional utility. Deposition potentials from the pyrophosphate bath and cyanide bath were -0.60V and -0.92V (vs. SCE) respectively. Bath limiting currents were in the vicinity of 3mA/cm2. The cathode current efficiencies of the baths showed the same tendency-an increase in cathode current density reduced current efficiency while a rise in pH or bath temperature increased it. Pyrophosphate gold deposits were more satisfactory cyanide deposits in soldering. The X-ray deffraction patterns of both deposits exhibited random crystal structures. SEM observation showed that while gold deposited from the cyanide bath was dentritic that from the pyrophosphate bath were cubic and showed bright tones. A correspondence was found between grain size and the hardness of the deposits: harder deposits were obtained from the cyanide than from the pyrophosphate bath. However, differences in size caused by different electrolytic conditions was small in the pyrophosphate bath, so that relatively stable deposits could be obtained.
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