Ceramics used as intermetallic diffusion barriers in Pd-based composite membranes sputtered on porous nickel supports

A ceramic barrier was introduced onto the surface of a porous nickel support (PNS) to prevent intermetallic diffusion. Al2O3 and ZrO2 were deposited on the PNS by RF sputtering to a thickness of 200 nm. Pd and Au were then deposited by DC and RF sputtering with thicknesses of 3 μm and 0.5 μm, respectively, on the PNS with the diffusion barrier. The permeation measurement was carried out using hydrogen and helium at 723 K and a pressure difference of 100-2000 kPa. The gas permeation tests confirmed that the hydrogen permeation flux increased with increasing pressure difference and reached 4.07 mol m−2 s−1 at 2000 kPa with an H2/He selectivity of more than 5000. The ZrO2 barrier membrane provided a flux of 1.5 times higher than that achieved by the Al2O3 barrier membrane. The sputtering method was successful in depositing intermetallic diffusion barriers and Pd-Au alloy layers.