Characterization of electroless plated palladium–silver alloy membranes

Abstract

Palladium and silver coated membranes were prepared using electroless plating. Palladium–silver alloy membranes were synthesized by successive palladium and silver depositions on the same membrane support. Full characterizations of the pure palladium and pure silver membranes were performed using scanning electron microscopy (SEM), X-ray diffractometry (XRD) and proton induced X-ray emission (PIXE). Metal coated membranes were heat treated for 5 h in a hydrogen atmosphere at 650°C. The effect of the palladium and silver deposition sequence on coating adhesion and metal distribution in the alloy matrix after heating were investigated. By depositing first silver 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. However, when palladium was deposited first, the alloy penetrated at least 3 μm into the support and the palladium and silver concentration profiles across the thickness of the film were asymmetric.