| Induced Electrochemical Codeposition of Rhenium and Tungsten Alloys with Iron-Group (and other) Metals Noam Eliaz1; Eliezer Gileadi2; 1DEPT. MATERIALS SCIENCE AND ENGINEERING, TEL-AVIV UNIVERSITY, Tel Aviv, Israel; 2SCHOOL OF CHEMISTRY, TEL-AVIV UNIVERSITY, Tel Aviv 6997801, Israel; PAPER: 12/Physical/Plenary (Oral) SCHEDULED: 14:25/Fri. 25 Oct. 2019/Aphrodite B (100/Gr. F) ABSTRACT: The term "induced codeposition" was already coined by Brenner in 1963 to describe a process where certain elements such as tungsten (W),that cannot be deposited alone from their aqueous solutions, are readily codeposited with iron-group metals. Indeed, alloys of W with iron-group metals can readily be formed using, for example, a solution of NiSO<sub>4</sub> and Na<sub>2</sub>WO<sub>4</sub>, with citric acid added as a complexing agent. In this particular case, it was shown that the NiW alloy is deposited from an adsorbed complex containing both metals, while Ni is also deposited in parallel reactions from its complex with citrate. The term induced codeposition may also be used to describe a process where a metal, that can barely be deposited alone, with a low current efficiency (FE) and poor adherence of the deposit, is readily deposited in the presence of other metal ions. This is the case of rhenium (Re), which can be electroplated alone at FE a ≤ 7% and poor coating quality. By adding a suitable iron-group metal salt to the bath, we have obtained coatings with a Re content as high as 93 at.% and a FE as high as 96%. In this plenary presentation, we review our study of the electrodeposition and electroless plating of Re-based alloys. Issues such as the catalytic effect of iron-group metals on the deposition of Re, the early stages of deposition, the effects of bath additives and pulse plating, electroless plating, and the associated microstructures are discussed. We also discuss the effect of other alloying elements (e.g. Sn or Ir) on the resulting deposition process and microstructure. Similarities and differences compared to induced codeposition of W are discussed. The fundamental aspects are complemented by some applied aspects, e.g. with respect to thermal barrier coatings and catalysis. References: 1) N. Eliaz, T.M. Sridhar and E. Gileadi, Electrochim. Acta, 50(14) (2005) 2893-2904. 2) N. Eliaz and E. Gileadi, Chapter 4, in Modern Aspects of Electrochemistry, Vol. 42, eds. C.G. Vayenas, R.E. White and M.E. Gamboa-Aldeco, Springer, New York (2008) 191-301. 3) A. Naor, N. Eliaz and E. Gileadi, J. Electrochem. Soc., 157(7) (2010) D422-D427. 4) A. Naor-Pomerantz, N. Eliaz and E. Gileadi, Electrochim. Acta, 56 (2011) 6361-6370. 5) O. Berkh, N. Eliaz and E. Gileadi, J. Electrochem. Soc., 161(5) (2014) D219-D226. *** The first ever open-access manuscript of the Journal of the Electrochemical Society. 6) T. Nusbaum, B.A. Rosen, E. Gileadi and N. Eliaz, J. Electrochem. Soc., 162(7) (2015) D250-D255. 7) A. Duhin, A. Inberg, N. Eliaz and E. Gileadi, Electrochim. Acta, 174 (2015) 660-666. 8) B.A. Rosen, E. Gileadi and N. Eliaz, Catal. Commun., 76 (2016) 23-28. 9) S.I. Baik, A. Duhin, P.J. Phillips, R.F. Klie, E. Gileadi, D.N. Seidman and N. Eliaz, Adv. Eng. Mater., 18(7) (2016) 1133-1144. 10) N. Eliaz and E. Gileadi, Physical Electrochemistry: Fundamentals, Techniques, and Applications, Wiley-VCH, 2nd Edition. ISBN: 978-3-527-34139-9 (2019). |
