Electropolishing of WCu composite in a deep eutectic solvent
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Electropolishing of WCu composite in a deep eutectic solvent Anna Kityk1,2 · Miroslav Hnatko2,3 · Viliam Pavlik3 · Miroslav Boča3 Received: 13 July 2020 / Accepted: 9 November 2020 © Institute of Chemistry, Slovak Academy of Sciences 2020
Abstract The possibility of using a deep eutectic mixture of choline chloride and ethylene glycol in a 1:2 molar ratio (ethaline) for the electropolishing of a WCu composite (~ 71 wt.% of W and ~ 12 wt.% of Cu) has been shown for the first time. It was demonstrated that 20 min electropolishing in ethaline at a temperature of 25 ºC causes significant leveling of the surfaces and decreases the amount of defects and the depth of scratches. It was also found that electropolishing of WCu composite in ethaline was accompanied by changes in the elemental surface composition: a decrease in Cu, C and O concentrations and an increase in W concentration were observed. It was shown that such changes in the surface elemental composition of WCu samples, together with the leveling of the surfaces and elimination of defects, led to almost a fourfold improvement in the corrosion resistance of the samples in 10 wt.% aqueous NaCl solution. Keywords WСu composite · Electropolishing · Deep eutectic solvent · Cyclic voltammogram · Corrosion resistance
Main text sections Over the last few decades, WCu materials have found many fields of applications and attracted considerable interest from numerous researchers due to the non-trivial combination of different properties of the material’s components (Deng et al. 2019; Chen et al. 2017; Liang et al. 2017; Li et al. 2020). According to the standard definitions, WCu materials are not alloys, but composites, since two components (W and Cu) are mutually insoluble (Li et al. 2020). Modern industry offers WCu composites with different ratios of W and Cu (the W content in such composites can range from 50 to 90 wt. %), which allows the variation of material properties over a certain range (increasing the amount of W in composites significantly increases the density, hardness, resistivity, and bending strength). It should also be noted that
* Anna Kityk [email protected] 1
Ukrainian State University of Chemical Technology, Gagarin Ave., 8, Dnipro 49005, Ukraine
2
Centre of Excellence for Advanced Materials Application, Dúbravská St, Slovak Academy of Sciences, 5807/9, 845 11 Bratislava, Slovak Republic
3
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská St., 9, 845 36 Bratislava 45, Slovak Republic
WCu composites are characterized by an attractive combination of high electrical and thermal conductivity, while at the same time, being heat resistant and having a low thermal expansion coefficient (Deng et al. 2019; Chen et al. 2017). This unique combination of properties of WCu composites makes them excellent materials for electrodes, heat sinks in microelectronics, and contact materials in vacuum, oil and gas systems, and also raises the possibility of using them for welding and other tasks (Deng et al.
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