Electrodeposition of Zn-Mn coatings on steel from 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide ionic liquid

This work studies the electrodeposition of Zn-Mn alloy on high-resistance steel substrates from 1-ethy1-3-methylimidazolium-bis (trifluoromethanesulfonyl) imide ionic liquid and Zn and Mn bis (trifluoromethanesulfonyl) imide salts and their sacrificial corrosion protection properties. The cleaning of the electrodeposited Zn-Mn alloy for the purpose of removing any ionic liquid remains has proved to be a fundamental step. A variety of solvents were tested, showing that the best results were obtained with dichloromethane (CH2Cl2) since this solvent removed the ionic liquid residues without reacting with the electrodeposited coating. The Zn/Mn ratio in the electrodeposited material is dependent on the concentration of the solution salt, as well as on the potential chosen for electrodeposition. The most promising Zn-Mn alloy was electrodeposited from 0.15 M Zn to 0.3 M Mn salt solution at -1.8 V. The electrodeposited coating under these conditions shows a shift in the corrosion potential towards nobler values due to the Mn incorporation in the alloy, and has sacrificial properties that show lower dissolution rates than Zn when galvanic coupled with steel with an area ratio of 1:1. (C) 2014 Elsevier B.V. All rights reserved.