Abstract
The electrodeposition behavior of Ni-Cd alloys was investigated using sulfate baths. It was found that over a wide range of electrolysis conditions the codeposition behavior of Ni-Cd alloys was anomalous because the Ni content of the alloys was extremely low in comparison with the metal-percentage of Ni in the baths. The Ni content of the alloys increased with increases in the Ni concentration in the baths, current density, pH and temperature, and with a decrease in the sodium acetate concentration in the baths.
The polarization curves were measured during the deposition of Ni-Cd alloy and each component metal. In the alloy plating bath, Ni deposition showed significant polarization which brought about the anomalous codeposition while Cd deposition began to occur at around the equilibrium potential of Cd. The high polarization of Ni deposition was observed even in a Ni single bath. Therefore, the anomalous codeposition appearing in the Ni-Cd system is not attributed to the interaction of both ions during their simultaneous discharge, but to the polarization peculiar to single Ni deposition from aqueous solutions.
