Cr-Based intermetallic diffusion barrier for stainless steel supported palladium membrane

Abstract

Aimed at developing an effective Cr-based intermetallic diffusion barrier, this study prepared three Cr₂O₃ and one CrN films employing: (1) direct oxidation of the stainless steel support, (2) oxidized Cr-electroplating, (3) oxidized Cr-sputtering in argon atmosphere and (4) Cr-sputtering in nitrogen atmosphere. The oxidation step was performed in oxygen atmosphere and the most suitable condition (temperature and time) was determined by X-ray photoelectron spectroscopy to be at 600°C for 6 hours. The efficacies in preventing intermetallic diffusion were assessed employing SEM-EDS to analyze the elemental content of the palladium layer after being heated for 24 hours at 450, 500 or 550°C. All Cr-based thin films can, at varying degrees, protect the palladium layer from metal diffusion. The Cr₂O₃ intermetallic diffusion barriers were more effective than the CrN. The Cr₂O₃ film was better prepared by either (2) or (3) since the film formed via (1) was extremely thin and did not continuously cover the surface of the support due to the inadequate availability of Cr in the stainless steel. Other results including the effects of the barrier on morphology which directly influence the properties and overall usefulness of the palladium layer were also reported.