Electrodeposition of Al-W-Mn Ternary Alloys from the Lewis Acidic Aluminum Chloride−1-Ethyl-3-methylimidazolium Chloride Ionic Liquid

Abstract

The electrodeposition of non-equilibrium ternary Al-W-Mn alloys was examined in the Lewis acidic 66.7-33.3 m/o aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl 3 -[C 2 mim]Cl) ionic liquid (IL). K 3 [W 2 Cl 9 ] and MnCl 2 were added to provide sources of W and Mn. The Al-W-Mn alloys were deposited on Cu wire substrates rotated at a fixed rate of 1000 rpm by using a dc galvanostatic method. The W content in the ternary Al-W-Mn alloys decreased with an increase in the deposition current density and was independent of the K 3 [W 2 Cl 9 ] and MnCl 2 concentrations in the plating solution. However, both the current density and the metal salt concentrations affected the Mn content of the ternary alloys. X-ray diffraction and composition analysis of the resulting Al-W-Mn deposits revealed the presence of an amorphous non-equilibrium alloy phase without chloride contamination. The chloride-induced pitting potential of the Al-W-Mn ternary alloys was found to be superior to that of the related binary alloys, Al-W and Al-Mn, indicating that the presence of two transition metal solutes has a beneficial additive effect on the corrosion resistance of Al. The many useful features and novel physical properties of ionic liquids (ILs), which are also called room-temperature or ambient-temperature molten salts, make them fertile media for future technologies.1-3 Thermodynamically, aluminum metal cannot be electrodeposited from aqueous solutions containing Al(III), because hydrogen is produced before the Al(III) can be reduced. However, Al can be deposited from aprotic, nonaqueous solutions, e.g., organic solvents containing aluminum salts and from chloroaluminate ILs. 4 However, all processes involving the electrodeposition of Al from organic solvents are based on volatile, flammable solvents and pyrophoric aluminum salts, greatly complicating large-scale aluminum plating operations. As a result, one of the fastest emerging technologies based on ILs is the electrodeposition of aluminum and its alloys from chloroaluminate ionic liquids. Although reactive with moisture, these ILs are virtually non-flammable and have negligible vapor pressure. Among the chloroaluminates, AlCl 3 -1-ethyl-3-methylimidazolium chloride (AlCl 3 -[C 2 mim]Cl) IL is under development for industrial-scale aluminum plating and for lab-scale aluminum alloy electrodeposition. mim]Cl IL. The processes leading to these alloys can be divided into underpotential and overpotential deposition. 5 The former alloys are deposited thermodynamically; i.e., their composition as a function of potential can be calculated from the Nernst equation.5 Al-Cu and Al-Ag alloys form by this underpotential mechanism. However, they tend to suffer from significant chloride contamination. The overpotential deposition results in stable non-equilibrium alloy phase with uniform composition and structure. Furthermore, the non-equilibrium alloys exhibit similar chloride-induced pitting potentials as those prepared by physical non-equilibrium alloying methods such as rapid * Elect...

Review—Electrochemical Surface Finishing and Energy Storage Technology with Room-Temperature Haloaluminate Ionic Liquids and Mixtures

“…Included in this list are Al-Hf, 72 Al-W, 73 Al-In-Sb, 74 Al-Mo-Ti, 75 and Al-W-Mn. 76 As discussed in our previous review, 71 we categorized Al alloy electrodeposition from haloaluminate RTILs into three main types. Here, we focus only on "overpotential-driven" Al-M 1 and Al-M 1 -M 2 alloy deposition because the most significant results are obtained only in this area.…”

“…This result was noted during previous studies of Al alloy electrodeposition from this same RTIL system, 74,75,94 and it is based on the fact that the concentration of K 3 [W 2 Cl 9 ] in the solvent is much smaller than the concentration of the reducible Al(III) and Mn(II) species. Figure 14 also shows that -j Mn increases with -j t and decreases with a decrease in MnCl 2 concentration in the solutions 76 The salt concentrations added to the IL were:…”

Tailoring lixiviant properties to optimise selectivity in E-waste recycling

“…22 One of the main benets of using an IL or DES is the minimisation or lack of oxide/ hydroxide chemistry, allowing the accessibility of metals and their alloys that generally could not be achieved in aqueous systems, including aluminium, magnesium, and germanium. 14,[23][24][25] By adding water to decrease the viscosity, there is a chance that passivating oxide or chloride layers may form on the more reactive metals during processing, and hinder dissolution processes, which may make the process unusable, or might instead impart some selectivity of dissolution. The most commonly used version of the DES formed from ethylene glycol and choline chloride has a 2 : 1 molar ratio of EG : ChCl.…”

Template-Free Fabrication of Diameter-Modulated Co-Zn/Oxide Wires from a Chlorozincate Ionic Liquid by Using Pulse Potential Electrodeposition

“…25,26 Nanowires that are difficult to be electrodeposited from aqueous baths have been successfully electrodeposited from various ILs with template-assisted [27][28][29][30][31] and template-free methods. [32][33][34][35][36][37][38][39][40][41][42][43] Recently, by taking the advantage of the unique properties of chloroaluminate ILs, 44 we have demonstrated the template-free electrochemical fabrication of diameter-modulated Al wires can be achieved from a Lewis acidic chloroaluminate ionic liquid (IL) by using a pulse potential deposition method. 45 In that report, the deposited wire diameter was thinner when the potential was pulse at a more negative cathodic value, and the wire diameter got thick when the potential was pulsed to a less negative cathodic value, and by repeating the pulse sequence, wires with modulated-diameter were obtained.…”