Fabrication of Thin Palladium-Silver Alloy Film by Using Electroplating Technique

A thin Pd-Ag alloy film, which will be applied to fabricate membranes for hydrogen separation, was successfully deposited using an electroplating technique. The plating solution for the formation of a thin Ag-rich Ag-Pd film for electric contact consisted of PdCl2, AgNO3, HBr, and HNO2. An improvement of the electrolytic bath was achieved by a pH control, which was kept constant at 6.6 and by the addition of H3BO3 and C2H5NO2. When the concentration of PdCl2 in the bath was increased to 4 times as high as that of the reported bath, the deposited film had the preferable composition of 72mass% Pd and 28mass% Ag. It was confirmed by SEM observations, and XRD, and EPMA analyses that the deposited film possessed a negligible amount of cracks and pinholes and was composed of Pd-Ag alloy without exhibiting any concentration gradient along the film thickness. [doi:10.2320/matertrans.48.1119]