Characterization of electroless plated palladium-silver alloy membranes

Palladium and silver coated membranes were prepared using electroless plati ng. Palladium-silver alloy membranes were synthesized by successive palladi um and silver depositions on the same membrane support. Full characterizati ons of the pure palladium and pure silver membranes were performed using sc anning electron microscopy (SEM), X-ray diffractometry (XRD) and proton ind uced X-ray emission (PIXE). Metal coated membranes were heat treated for 5 h in a hydrogen atmosphere at 650 degrees C. The effect of the palladium an d silver deposition sequence on coating adhesion and metal distribution in the alloy matrix after heating were investigated. By depositing first silve r and then palladium, the palladium to silver ratio across the thickness of the film remained constant after heat treatment and it resulted in only a small amount of the alloy penetrating into the support membrane pores. Howe ver, when palladium was deposited first, the alloy penetrated at least 3 mu m into the support and the palladium and silver concentration profiles acr oss the thickness of the film were asymmetric. (C) 1999 Elsevier Science S. A. All rights reserved.