Electrochemistry of Titanium and the Electrodeposition of Al-Ti Alloys in the Lewis Acidic Aluminum Chloride–1-Ethyl-3-methylimidazolium Chloride Melt

The electrodeposition of Al-W alloy films in a Lewis acidic 1-ethyl-3-methyl-imidazolium chloride (EMIC)-AlCl 3 ionic liquid using W 6 Cl 12 as the W ion source was investigated. W 6 Cl 12 dissolved in the ionic liquid at a higher concentration than other W ion sources used in previous studies. Potentiostatic electrodeposition was performed in a bath containing W 6 Cl 12 at a concentration of 49 mM. Dense Al-W alloy films containing up to 12 at.% W were electrodeposited at potentials more negative than 0 V vs. Al/Al(III). The deposition current density at >0 V was lower than 0.3 mA cm −2 , while that for Al-W alloy films was higher and reached 38 mA cm −2 at −0.5 V. The deposition of W was induced by the deposition of Al. At lower W concentrations, the Al-W alloy films were composed of a super-saturated solid solution, and in the W content range of 9-12 at.% they comprised an amorphous phase. Potentiodynamic polarization and nano-indentation showed that the Al-W alloy films containing 10-12 at.% W exhibited high pitting corrosion resistance, high hardness, and low Young's modulus. Al metal has high oxidation and corrosion resistance, and its chloride-induced pitting corrosion resistance is enhanced by alloying with transition metals. Consequently, Al-transition metal alloys have attracted much research attention as corrosion-protective materials. Among these alloys, Al-W alloys containing approximately 10 at.% are known to exhibit the greatest resistance to pitting corrosion. 1Since the maximum solubility of W in Al phases is only 0.022 at.% at 640• C in the equilibrium state, 2 the formation of Al-W alloy films having high corrosion resistances requires non-equilibrium processes, such as sputtering, 1,3-8 ion implantation, 9 and electrodeposition. 10-12Of these methods, electrodeposition has particular advantages in that a uniform film can be formed relatively quickly and continuously, onto substrates having complex shapes, using simple equipment. Various Al-based alloy films have been electrodeposited in molten salts such as NaCl-AlCl 3 with the addition of ion sources for the alloy component. Recently, electrodeposition using ionic liquids has become more popular owing to their low melting point and low volatility. A representative ionic liquid used for the electrodeposition of Al alloys is Lewis acidic 1-ethyl-3-methylimidazolium chloride (EMIC)-AlCl 3 (where the AlCl 3 /EMIC molar ratio >1 Al-Mn, 18 and Al-Hf 19 are available in the literature. A previous study revealed that electrodeposition in a EMIC-AlCl 3 bath with the addition of W(IV) chloride (WCl 4 ) yielded Al-W alloys, but the W content was lower than 1 at.%.10 Recently, the electrodeposition of Al-W alloy films from an EMIC-AlCl 3 bath with the addition of the W(III) compound K 3 W 2 Cl 9 was reported.11,12 Although the W content of the Al-W alloys reached nearly 96 at.%, the deposits with high W content had powdery morphologies. When the current density was high (>20 mA cm −2 ), dense Al-W alloy films were obtained, but the W content decreased t...

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confidence: 99%

Electrodeposition of Al-W Alloy Films in a 1-Ethyl-3-methyl-imidazolium Chloride-AlCl₃Ionic Liquid Containing W₆Cl₁₂

Higashino

Miyake

Fujii

et al. 2017

“…Figure 4 shows SEM images of Al-W-Mn alloy samples prepared at three different applied current densities under two different bath conditions. In each bath, as is the case for Al-Ti alloy electrodeposition from the 66.7 m/o IL, 6 the nodule size of the alloy samples becomes larger with an increase in the magnitude of −j t . At higher MnCl 2 bath concentrations, spherical shaped deposits were obtained regardless of the applied current densities as shown in Figs.…”

Section: Resultsmentioning

confidence: 91%

“…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. 5 A great number of aluminum-transition metal alloys including AlCu, 5 Al-Ag, 5 Al-Ni, 5 Al-Ti, [5][6][7] Al-V, 8 Al-Cr, 5 Al-Mn, 5 Al-Mo, 9 AlZr, 10 Al-Hf, 11 Al-W, 12 Al-In-Sb, 13 Al-Mo-Ti, 14 and Al-Mo-Mn 15 have been electrodeposited from the Lewis acidic composition [percent mole fraction of the AlCl 3 > 50] of the AlCl 3 -[C 2 mim]Cl IL. The processes leading to these alloys can be divided into underpotential and overpotential deposition.…”

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confidence: 99%

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

Tsuda

Ikeda

Imanishi

et al. 2015

Self Cite

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...

“…Cyclic voltammetry was conducted by a common cell previously reported in our paper. 31,42,43 A platinum wire electrode (Nilaco, φ 1 mm, 99.8%) was used as the working electrode, and coils of 1 mm diameter aluminum wire (Nilaco, 99.999%) were used as the counter and reference electrodes. The aluminum electrodes were cleaned with a mixture of concentrated H 2 SO 4 , HNO 3 , and H 3 PO 4 , rinsed with distilled H 2 O, and dried under vacuum before use.…”

Section: -35mentioning

confidence: 99%

Electrochemical Energy Storage Device with a Lewis Acidic AlBr₃−1-Ethyl-3-methylimidazolioum Bromide Room-Temperature Ionic Liquid

Tsuda¹,

Kokubo²,

Kawabata³

et al. 2014

Self Cite

Now room-temperature ionic liquid (RTIL) is becoming a general term in the fields of science and technology owing to its useful physicochemical properties. A great number of applications with RTIL are proposed to date. Here we report an original electrochemical energy storage device with a Lewis acidic 60.0-40.0 mol% AlBr 3 −1-ethyl-3-methylimidazolioum bromide ([C 2 mim]Br) RTIL. The unique electrochemical reactions related to [AlBr 4 ] − anion on the positive electrode have a crucial role in the energy storage device. The charge-discharge ratio for the beaker cell prepared in this investigation was almost 100% at 2.0 ∼ 5.0 mA (150 ∼ 370 mA g −1 for activated carbon fiber cloth) if the cutoff voltage for the charging process was less than 1.70 V. The clear self-discharge behavior was not observed and the cell capacity after 100 cycles was identical to the maximum value. Rechargeable battery is a quite important energy storage device for sustaining our modern life. It is well-known that there are many types of rechargeable batteries. Of these, lithium-ion rechargeable battery has been already used in the various fields, but minor elements including lithium and cobalt are commonly used for the battery. It will become a major difficulty by further development of lithium-ion battery industry in the future. In addition, it seems to be unsuitable for a large scale electric storage system because of its insufficient rapid charge-discharge characteristics and safety issue. In recent years, a multivalent-metal ion, e.g., Mg(II), rechargeable battery system has attracted attention as a next generation high-capacity battery system because it can flow a larger current exceeding the lithium-ion rechargeable battery. [1][2][3][4] However it is difficult to electrochemically reduce such multivalent-metal ion due to its negative electrode potential. Even if the metal ion is reduced to metal state, in many cases, it would not achieve a sufficient coulomb efficiency in the chargedischarge process since the highly-reactive metal deposited on the negative electrode during the charging process easily reacts with the electrolyte. Another problematic point is that there are a limited number of choices on active materials for the positive electrode. If any, the active material does not show a favorable coulomb efficiency and the charge-discharge rate is not enough compared to that for current Li battery system.2-4 Another possible high-capacity electrochemical energy storage system is a redox flow battery, which has a low environmental impact and can store a huge energy. Unfortunately still many scientific and technological challenges, such as improvement in the electrolyte potential window and development of the separator that can perfectly protect the catholyte and anolyte against their undesirable contamination, remain. 5-9Room-temperature ionic liquids (RTILs) that are liquid salts at room-temperature, e.g., 298 K, have received considerable attention as novel reaction media, especially in this decade, because of their desirable ...