Electrodeposition of rhenium-nickel alloys from aqueous solutions

Rhenium-nickel alloys were deposited on copper substrates in a small three-electrode cell. under galvanostatic conditions. The bath solution consisted of ammonium perrhenate, citric acid and nickel sulfamate. The effects of bath composition and deposition time were studied. The Faradaic efficiency (FE) and partial deposition current densities were calculated based on mass gain and elemental analysis using energy dispersive spectroscopy. The surface morphology was characterized by scanning electron microscopy. The thickness of the coating was measured on metallographic cross-sections. The results are discussed with emphasis on routes to increase the Faradaic efficiency and rhenium content in the coating. A plausible mechanism for the electrodeposition of rhenium-nickel alloys is presented. (C) 2009 Elsevier Ltd. All rights reserved.