EDTA溶液からの銀-パラジウム合金電析

抄録

Silver-palladium alloy deposition from alkaline solutions containing EDTA, ammonium carbonate, and ammonia water has been studied. The cathodic potential for alloy deposition was -0.37V (vs. SCE) which was between those of Ag⁺ and Pd²⁺ single ion solutions. It was found that the silver deposition became the condition of diffusion controll, when palladium was deposited. This deposition of silver-palladium alloy was an anomalous codeposition, and the palladium content of electrodeposited alloy was always smaller than that of the electrolyte. The amount of palladium codeposited tended to increase with an increased in bath pH or current density, and decreased with an increase in bath temperature. Cathode current efficiency was about 70% irrespective of bath temperature. It improved with an increase in pH, and tended to decrease with higher current density.The electrodeposit of silver-palladium alloy had a crystal structure with no remarkable orientation. SEM photographs showed good adhesion and a smooth surface with no cracks.