Novel Electroless Plating of Ruthenium for Fabrication of Palladium-Ruthenium Composite Membrane on PSS Substrate and Its Characterization

This paper focused on a novel method of electroless plating ruthenium (Ru) on solid or porous substrates like porous stainless steel (PSS) discs or ceramic tubes. A novel complexing plating bath of Ru was developed. It is proven that Ru can be deposited directly on these substrates by the bath at a temperature of 328 K and strong alkaline environment. TGA, SEM, EDX and XRD confirmed the successful deposition of Ru. Relationships among plating rate, plating time, plating bath temperature and concentrations were also investigated. The Ru plating procedure was optimized. Based on the optimized procedure, a Ru layer was deposited by electroless plating of Ru onto the surface of pretreated aluminum-oxide modified PSS substrate. A 7.6 µm thick Pd-Ru membrane could be fabricated by electroless plating with a palladium (Pd) layer overlying the PSS substrate and a Ru layer overlying the Pd layer. Helium leakage and hydrogen permeation tests confirmed that the membrane was free of defects. Hydrogen diffusion through the Pd-Ru membrane was found to be the rate-controlling step in permeation. A new Pd-Ru composite membrane had the same features and permeation behavior as a previous one, indicating that electroless plating of both Ru and Pd is reliable and repeatable.