2022-Sustainable Industrial Processing Summit
SIPS2022 Volume 4 Kipouros Intl. Symp. Molten Salt, Ionic & Glass-forming Liquids & Powdered Materials
| Editors: | F. Kongoli, R. Fehrmann, V. Papangelakis, I.Paspaliaris, G. Saevarsdottir. |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2022 |
| Pages: | 100 pages |
| ISBN: | 978-1-989820-40-7(CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
CD shopping page
Electrochemical Dealloying of Ag – Zn Alloys in Eutectic Alkali Chlorides Melts
Nina Kulik1; Nickolay Shurov1; Nickolay Tkachev2;1INSTITUTE OF HIGH TEMPERATURE ELECTROCHEMISTRY OF THE URAL BRANCH OF THE RUSSIAN ACADEMY OF SCIENCESS, Ekaterinburg, Russian Federation; 2INSTITUTE OF HIGH-TEMPERATURE ELECTROCHEMISTRY RAS, Ekaterinburg, Russian Federation;
Type of Paper: Regular
Id Paper: 148
Topic: 13
Abstract:
KEYWORDS: dealloying, molten salts, Ag-Zn alloys
ABSTRACT
Electrochemical dealloying as a promising method for producing metals with a highly developed surface is widely studied in aqueous solutions [1, 2]. However, there are very few works devoted to studying it in liquid salt ionic media at elevated temperatures.The possibilities of using anhydrous high-temperature ionic electrolytes for the production of porous metals have not yet been disclosed, and the regularities of dealloуing in such media have not been clarified.
The purpose of this work is to establish the features of the selective anodic dissolution of zinc from its alloys with silver in еutectic melts of alkali chlorides.Two homogeneous Ag-Zn alloyswere prepared by fusing the components under a layer of molten salts. The zinc content in the alloys was 67 and 46 mol.%, which corresponded to the ε and β phases of the phase diagram and the investigatedtemperature interval was from 300 up to 500 °С. EutecticsLiCl0.57CsCl0.26KCl0.17and CsCl0.455KCl0.245NaCl0.30was used as electrolytes.Three-electrode cell was designed for the experiments. A glassy carbon crucible served as a reservoir for the melt and, at the same time, as the counter electrode. The reference electrode was a silver wire immersed in the same melt with addition of 3 mol. % AgCl in a micro-perforated alundum tube. Selective anodic dissolution of alloys carried out in potentio- and galvanostatic modes varying the voltage and the current density.
Practically full zinc removal was achieved at a current density of about 20 mA/cm2 in the case of the ε phase and 7 mA/cm2 for the β phase in galvanostatic mode. The selectivity of the dealloyng decreased with the increasing current density. Typical homogeneous porous structures obtained on the surface of Zn0.67Ag0.33 alloywith pores and ligaments of approximately the same size lying in the range of 0.5–5 μm. For the Zn0.46Ag0.54, dendritic structures with sizes of silver particles of the order of 0.5–4 and 5–20 μm formed. It was shown that the increase in the process temperature led to the coarsening of the porous structure.
Thus, we have shown the possibility of percolation-type electrochemical dealloying and found the best method for the most dezincification of the alloy. The regularities of the influence of the alloy composition, temperature and electrolysis mode on the composition and structure of the resulting product have been established.
This work was supported by Russian Foundation for Basic Researches (20-03-00267)
REFERENCES:
[1] J. Weissmüller, K. Sieradzki, MRS Bulletin, 43 (2018) 14-19.
[2] J. Zhang, Ch.M. Li, Chem. Soc. Rev., 41(2012)7016–7031.
Keywords:
Corrosion; Electrochemical; Metals;References:
[1] J. Weissmüller, K. Sieradzki, MRS Bulletin, 43 (2018) 14-19.[2] J. Zhang, Ch.M. Li, Chem. Soc. Rev., 41(2012)7016–7031.