Electrodeposition of Alloys of Rhenium with Iron-Group Metals from Aqueous Solutions

Rhenium (Re)-Me alloys (where Me=Ni, Fe, or Co) were deposited galvanostatically. The plating bath consisted of ammonium perrhenate, nickel or cobalt sulfamate, or iron sulfate, citric acid, and magnesium sulfamate. The effects of bath chemistry and deposition time on faradaic efficiency (FE), Re content, and partial deposition currents were determined. Rhenium contents as high as 93 atom % or FE values as high as 96% were attained in different solutions. The results are discussed, with emphasis on routes to increase the FE and Re content in the coating. The possible role of the second metal in the electrodeposition of Re is presented. A plausible mechanism by which addition of Ni, Fe, or Co to the solution enhances the rate of the deposition of Re is through a unique type of electroless deposition, in which the reducing agent is Me-0 formed in situ. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3430084] All rights reserved.