Characterization of palladium and palladium-silver alloy layers on stainless steel support

Pd and Pd/Ag layers were prepared by a technique of electroless plating on stainless steel supports. To form Pd/Ag layers, Pd layer was plated on an activated stainless steel (SS) sheet followed by Ag plating. The Pd/Ag-SS sheet composite was annealed at 873 K-973 K for 10 h -12 h in helium. Before annealing, the thickness of Pd layer and Ag layer on Pd/Ag-SS sheet composite was 7.6 mu m and 1.9 mu m, respectively. The formation of Pd/Ag alloy was observed on the SS sheet after annealing at 873 K for 12 h in helium. The ratios of Ag/(Pd+Ag) were 0.28 on the surface by XRF and 0.29 in the bulk by XPS. This result showed the formation of homogeneous Pd/Ag alloy on the SS sheet at that annealing condition. Helium permeances were measured at a pressure difference of I atm and room temperature. The permeances of porous stainless steel (PSS) tubes without and with 78 mu m Pd layer were 100 m(3)/m(2)h and 0.35 m(3)/m(2)h, respectively. This result showed the obtained membrane was an almost dense membrane.