Electrodeposition of Sn and NiSn alloys coatings using choline chloride based ionic liquids-Evaluation of corrosion behavior

The present paper presents several experimental results regarding the electrodeposition and corrosion behavior of Sn and NiSn alloy coatings from some choline chloride based ionic liquids, applied onto various metallic substrates including Cu and steel. There are discussed electrolytes containing Sn and Ni salts in choline chloride-ethylene glycol and choline chloride-malonic acid eutectic mixtures. The obtained Sn and Ni-Sn alloy deposits are adherent and uniform onto metallic substrates The Ni-Sn alloys contained about 62-72 wt% Sn according to EDX analysis, with a very slight variation against the applied current density domain. According to XRD investigations both electrochemical coatings showed a nanocrystalline structure, with average sizes of the crystallites between 50 and 80 nm for Sn and around 11-14.5 nm for NiSn alloy. To evaluate corrosion resistance of Sn and Ni-Sn alloy coatings, potentiodynamic polarization curves and electrochemical impedance spectra (at open circuit potential) in 0.5 M NaCl solution have been recorded after different immersion times of coated specimens. Different corrosion performances are discussed taking into account the used electrodeposition procedures. (C) 2013 Elsevier Ltd. All rights reserved.