Fabrication of a micro-porous Ti–Zr alloy by electroless reduction with a calcium reductant for electrolytic capacitor applications

Kikuchi, Tatsuya; Yoshida, Masumi; Taguchi, Yoshiaki; Habazaki, H.; Suzuki, Ryosuke O.

doi:10.1016/j.jallcom.2013.10.052

Cited by 9 publications

(14 citation statements)

References 29 publications

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“…In a previous investigation, we observed that excess calcium reductant caused the complete reduction of titanium and zirconium oxides. The details of the reduction setup used in the present investigation have been described elsewhere [44].…”

Section: Reduction Of Titanium Oxidementioning

confidence: 99%

“…Very recently, the authors have investigated the fabrication of a metallic titanium and zirconium micro-porous alloy by reduction with a calcium reductant in calcium chloride molten salt for novel electrolytic capacitor applications [44]. It is known that defect-free, high-capacitance composite anodic oxide films can be formed on substrates by anodizing a Ti-62.5 at% Zr alloy [45][46][47][48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

“…Fray, Farthing, and Chen investigated the cathodic deoxidation of metal oxides in calcium chloride and calcium oxide mixture molten salts and reported the production of metallic titanium [22][23][24][25][26] [32][33][34] through the FFC (Fray, Farthing, and Chen) Cambridge process. Several other research groups have also investigated the successive reduction of metal oxides based on electrolysis in molten calcium chloride [33][34][35][36][37][38][39][40][41].Very recently, the authors have investigated the fabrication of a metallic titanium and zirconium micro-porous alloy by reduction with a calcium reductant in calcium chloride molten salt for novel electrolytic capacitor applications [44]. It is known that defect-free, high-capacitance composite anodic oxide films can be formed on substrates by anodizing a Ti-62.5 at% Zr alloy [45][46][47][48][49][50][51].…”

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confidence: 99%

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Rapid reduction of titanium dioxide nano-particles by reduction with a calcium reductant

Kikuchi

Yoshida

Matsuura

et al. 2014

Journal of Physics and Chemistry of Solids

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Micro-, submicron-, and nano-scale titanium dioxide particles were reduced by reduction with a metallic calcium reductant in calcium chloride molten salt at 1173 K, and the reduction mechanism of the oxides by the calcium reductant was explored. These oxide particles, metallic calcium as a reducing agent, and calcium chloride as a molten salt were placed in a titanium crucible and heated under an argon atmosphere. Titanium dioxide was reduced to metallic titanium through a calcium titanate and lower titanium oxide, and the materials were sintered together to form a micro-porous titanium structure in molten salt at high temperature. The reduction rate of titanium dioxide was observed to increase with decreasing particle size; accordingly, the residual oxygen content in the reduced titanium decreases. The obtained micro-porous titanium appeared dark gray in color because of its low surface reflection. Micro-porous metallic titanium with a low oxygen content (0.42 wt%) and a large surface area (1.794 m 2 g -1 ) can be successfully obtained by reduction under optimal conditions. Key words: Titanium, Calcium, Calciothermic reduction, Nano-particles, Electrolytic capacitor IntroductionMetallic calcium can easily reduce a large number of metal oxides directly to metals because calcium has a strong reducing ability. The reduction of metal oxides with a calcium reductant in calcium chloride molten salt at high temperature, well known as the calciothermic reaction, has long been widely investigated by many researchers. During oxide reduction, calcium chloride molten salt acts as a suitable solvent and has a high solubility for calcium and calcium oxide as a byproduct formed by reduction. [11] are formed via reduction of these oxides with a calcium reductant in calcium chloride molten salt. The residual oxygen in the reduced metal decreases continuously by deoxidation with a calcium reductant [4]. Pure metals, alloys, and intermetallic compounds with a lower residual oxygen content can be successfully fabricated by a one-step reduction technique. Reduction with a calcium reductant is a simpler technique for the production of these metals without complicated processes such as the Kroll process, although reduction is a batch-type production method.In recent years, a method for the successive reduction of metal oxides was developed by electrolysis in calcium chloride and calcium oxide mixture molten salts. Ono and Suzuki reported that calcium oxide in molten calcium chloride becomes the reductant source for the reduction of metal oxides during constant-voltage electrolysis [12]. For example, metallic calcium formed electrochemically at a cathode reacts with metal oxides, and reduced metals with a low residual oxygen content can be formed (OS (Ono and Suzuki) Kyoto process). Metallic titanium [13][14][15], niobium [16], nickel [17], and other alloys and intermetallic compounds [18,19] can be formed via the OS process. In addition, the electrochemical decomposition of carbon dioxide gas by an advanced OS process using ...

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Section: Reduction Of Titanium Oxidementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Rapid reduction of titanium dioxide nano-particles by reduction with a calcium reductant

Kikuchi

Yoshida

Matsuura

et al. 2014

Journal of Physics and Chemistry of Solids

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“…Titanium and titanium alloy powders can also be produced by an indirect electrochemical reduction process of the relative oxides in molten CaCl 2 -CaO, namely, the well-known O-S (Ono-Suzuki) process 16,17) . For example, TiZr 18) , TiNbNi 19) as well as a biomedical alloy, Ti-29Nb-23Ta-4.6Zr (TNTZ) 20) with very low oxygen content were prepared by the method. Compared with other methods, the direct and indirect molten-salt electrochemical reduction methods only contain one step without merging the metal extraction and melting process, resulting in a lower energy consumption, i.e., 23.5 kWh/kg-TiNi alloy 21) and possibly low cost.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Preparation of Porous Ti–13Zr–13Nb Alloy and It's Corrosion Behavior in Ringer's Solution

Yin

Zhou

et al. 2017

Mater. Trans.

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A ternary titanium alloy (Ti-13Zr-13Nb (TZN)) was prepared by direct electrochemical reduction of a sintered TiO 2 -ZrO 2 -Nb 2 O 5 mixture in molten CaCl 2 at 850 C with an energy consumption of 17 kWh/kg-alloy. The electrolytic Ti alloy was well sintered with bright metallic luster, and it was in α+β dual phase and of porous structure with designed composition. The corrosion behaviors of the obtained TZN in Ringer s solution were tested by open circuit potential and potentiodynamic polarization measurements. The results show that the corrosion rate of the porous electrolytic TZN alloy is lower than that of commercial pure titanium (CP-Ti) after being immersed in Ringer s solution for 10 days. The one-step electro-reduction of mixed oxide powers in molten salts could be an energy ef cient and straightforward way to prepare porous implantable alloys.

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“…[1][2][3] Various transition metals can be directly reduced from their oxides with metallic calcium because of its strong reducing ability. Therefore, calciothermic reduction for industrial applications had been widely investigated by many research groups to date, and metallic titanium, 4-9 zirconium, 10,11 hafnium, 12 niobium, [13][14][15] tantalum, 16,17 nickel, 18 uranium, 19 and their alloys [20][21][22][23][24][25][26][27] can be successfully obtained via calciothermic reduction and advanced techniques. 28,29 Although carbon dioxide (CO 2 ) is an extremely stable chemical species in our environment, the chemical decomposition of CO 2 is an important technology for global environmental issues.…”

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confidence: 99%

Carbon Nanotube Synthesis via the Calciothermic Reduction of Carbon Dioxide with Iron Additives

Kikuchi

Ishida

Natsui

et al. 2015

ECS Solid State Letters

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The novel fabrication of multi-walled carbon nanotube (MWCNT)/cementite (Fe3C) nanocomposites was demonstrated via the calciothermic reduction of carbon dioxide (CO2) through electrolysis in molten CaCl2/CaO with iron additives at 1173 K. In this technique, CO2 generated from a graphite anode is reduced to carbon with a metallic calcium reductant formed on a graphite cathode via electrolysis in molten salt. Calciothermic reduction without iron additives resulted in the formation of onion-like carbons (OLCs) with spherical graphite layers and thin graphite sheets. In contrast, MWCNT/Fe3C nanocomposites and OLCs were successfully fabricated via calciothermic reduction with iron additives through their catalytic activities

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Fabrication of a micro-porous Ti–Zr alloy by electroless reduction with a calcium reductant for electrolytic capacitor applications

Cited by 9 publications

References 29 publications

Rapid reduction of titanium dioxide nano-particles by reduction with a calcium reductant

Rapid reduction of titanium dioxide nano-particles by reduction with a calcium reductant

Electrochemical Preparation of Porous Ti–13Zr–13Nb Alloy and It's Corrosion Behavior in Ringer's Solution

Carbon Nanotube Synthesis via the Calciothermic Reduction of Carbon Dioxide with Iron Additives

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