Electropolishing of Tin in an Amide-Type Ionic Liquid

Abstract

Anodic dissolution and electropolishing of Sn were investigated in an amide-type ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide. The rate of anodic dissolution was considered to be determined by the diffusion of anodically dissolved Sn(II) species. A large increase in the local viscosity during dissolution was observed in-situ by the impedance-type electrochemical quartz crystal microbalance, reflecting an increase in the local concentration of Sn(II) near the electrode. A shiny and smooth surface was obtained after anodic dissolution at 0.1 V vs Ag∣Ag(I) with agitation. A decrease in the surface roughness estimated by confocal laser scanning microscopy suggested electropolishing of Sn was possible in the ionic liquid within the electrochemical potential window probably due to the formation of the viscous layer near the electrode.

Advantages of Electrochemical Polishing of Metals and Alloys in Ionic Liquids

“…The authors studied the behavior of an Sn electrode under various experimental conditions. It is seen in Figure 13 that some scratches on the tin surface that resulted from the mechanical abrasion of the sample disappear after potentiostatic anodization at 0.1 V. The decrease in the roughness of the electrode from 283 to 79 nm after anodization in BMPNTf 2 leads to the shiny surface of tin due to the viscous layer formation on the metal [53]. The same polishing effect was observed for the galvanostatic anodization of tin (0.5 mA cm −2 ).…”

“…The same polishing effect was observed for the galvanostatic anodization of tin (0.5 mA cm −2 ). The role of the viscous layer formation in the surface finishing of the metal was established [53][54][55]. The Sn(2+) diffusion through the viscous layer near the electrode was found to be the rate-determining stage of electropolishing.…”

“…Ionic liquids based on the pyrrolidinium cation were also successively used for electropolishing of tin [53][54][55]. 1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMPNTf 2 ) was tested as an electrolyte for anodic dissolution of tin.…”

Electropolishing with Low Mass Loss for Additive Manufacturing of Ti6Al4V in Zinc Chloride-Urea Deep-Eutectic Solvent

“…Therefore, the development of electropolishing technologies for Ti6Al4V alloys should also be based on determining appropriate electrolyte and process parameters. 11 Regarding electropolishing technologies for melt-casted titanium alloys, the electrolyte is typically a high viscosity concentrated acid medium such as perchloric acid, phosphoric acid or sulphuric acid or a mixture of the last two mentioned.…”

Room-Temperature Preparation of Ta Ions-Containing Ionic Liquid and its Vapor Deposition toward Ta-Oxide Film Coating

“…In fact, there are some reports on the availability of ILs for electropolishing 12 of e.g. Ti, 13 Pt 14 Ni 15 and Sn 16 as well as for anodic dissolution of various metals. 17 These pioneering works encourage our attempt of the electroelution of metal Ta in IL, though there have been no reports on the electropolishing nor electroelution of metal Ta in ILs.…”