copper zinc nickel alloys are used for various applications including automotive synchronizer rings. They are characterized by high strength and wear resistance. In order to enhance the wear resistance, the alloys are plated on hard substrates like high-strength steels, aluminium and aluminium alloys or transparent conductive oxides such as indium tin oxide. Hence, obtaining a uniform and pore free metallic coating is essential to prevent the substrate from corrosion. Moreover, the metal coating shall also protect the substrate from physical damage and ensure good adhesion. Electrodeposition of metals from ionic liquids (ILs) is a promising solution to these challenges.
Ionic liquids provide different environments/electrolytes for electrodeposition, wide electrochemical windows, high thermal stability and improved ionic conductivity [1]. They also eliminate the mechanical instability problems caused by hydrogen evolution during the deposition process. Thus, the use of ILs for metal deposition has gained significant attention in recent years.
In particular, the electrochemical properties of ILs for zinc and Zn-based alloys have attracted considerable interest. A number of studies have been reported on the deposition of copper zinc nickel alloy from ILs such as ChCl/EG, CHCl/2, CHCl/4, CHCl/6 and CHCl/Urea. These ILs have been found to be suitable for the electrodeposition of bright and uniform Zn-Ni deposits with Ni contents in the range of 12-15 wt % that exhibit the g phase of the alloy.
A detailed investigation of the deposition process has revealed that adding additives to the ionic liquid significantly improves the overall performance and properties of the deposits. Among these additives, amines are the most widely used as they can promote the formation of Zn-Ni silicides and improve the surface coverage of the deposit.
