Yu-ki Taninouchi

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Electrochemical Deoxidation of Titanium in Molten MgCl₂–YCl₃

Chenyi Zheng, Takanari Ouchi, Lingxin Kong, Yu-ki Taninouchi, more

Metallurgical and Materials Transactions B > 2019 > 50 > 4 > 1652-1661

A new electrochemical deoxidation process for Ti, where a mixture of magnesium chloride and yttrium chloride (MgCl₂–YCl₃) is used as flux, was developed. In the new process, Ti and carbon were used as the cathode and anode, respectively. By elucidating the system using an E-pO²⁻ diagram and the experimental results, the reaction mechanism was proposed. Mg is deposited on the Ti cathode and reduces...

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Deoxidation of Titanium Using Mg as Deoxidant in MgCl₂-YCl₃ Flux

Chenyi Zheng, Takanari Ouchi, Akihiro Iizuka, Yu-ki Taninouchi, more

Metallurgical and Materials Transactions B > 2019 > 50 > 2 > 622-631

To reduce the oxygen level in titanium (Ti) to less than 1000 mass ppm O, using magnesium as the deoxidant at 1300 K (1027 °C), the activity of the deoxidation product (MgO), i.e., a_MgO, in the system must be reduced to less than 0.04, from a thermodynamic viewpoint. In this study, we developed a new deoxidation technique for Ti, by adding yttrium chloride (YCl₃) to magnesium chloride (MgCl₂) flux,...

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Thermodynamic Analysis of Deoxidation of Titanium Through the Formation of Rare-Earth Oxyfluorides

Toru H. Okabe, Yu-ki Taninouchi, Chenyi Zheng

Metallurgical and Materials Transactions B > 2018 > 49 > 6 > 3107-3117

In this work, the possibility of the direct removal of oxygen species from metallic Ti through the formation of rare-earth oxyfluorides has been investigated from a thermodynamic viewpoint. The deoxidation limit of β-Ti using rare-earth metals (M: Y, La, Ce, and Nd) as deoxidants was evaluated. It was found that Ti metal with an oxygen concentration of 200 mass ppm or less could be theoretically obtained...

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Dissolution Behavior of Iron and Steel Materials in Liquid Magnesium

Yu-ki Taninouchi, Katsuhiro Nose, Toru H. Okabe

Metallurgical and Materials Transactions B > 2018 > 49 > 6 > 3432-3443

The dissolution of metallic elements from Fe and steel materials into pure liquid Mg was investigated with the aim of improving control of impurities in Mg during processes such as Mg-alloy production and Ti smelting. Pure Mg was melted between 1073 and 1323 K (800 and 1050 °C) for 24 to 96 hours in closed crucibles made of pure Fe, low-carbon steel, or austenitic stainless steel SUS316. From the...

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Recovery of Platinum Group Metals from Spent Catalysts Using Iron Chloride Vapor Treatment

Yu-ki Taninouchi, Toru H. Okabe

Metallurgical and Materials Transactions B > 2018 > 49 > 4 > 1781-1793

The recovery of platinum group metals (PGMs) from spent automobile catalysts is a difficult process because of their relatively low contents in the scrap. In this study, to improve the efficiency of the existing recycling techniques, a novel physical concentration method involving treatment with FeCl₂ vapor has been examined. The reactions occurring between typical catalyst components and FeCl₂ vapor...

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Thermodynamic Considerations of Direct Oxygen Removal from Titanium by Utilizing the Deoxidation Capability of Rare Earth Metals

Toru H. Okabe, Chenyi Zheng, Yu-ki Taninouchi

Metallurgical and Materials Transactions B > 2018 > 49 > 3 > 1056-1066

Oxygen removal from metallic Ti is extremely difficult and, currently, there is no commercial process for effectively deoxidizing Ti or its alloys. The oxygen concentration in Ti scraps is normally higher than that in virgin metals such as in Ti sponges produced by the Kroll process. When scraps are remelted with virgin metals for producing primary ingots of Ti or its alloys, the amount of scrap that...

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Enhanced Dissolution of Platinum Group Metals Using Electroless Iron Deposition Pretreatment

Yu-ki Taninouchi, Toru H. Okabe

Metallurgical and Materials Transactions B > 2017 > 48 > 6 > 2866-2872

In order to develop a new method for efficiently recovering platinum group metals (PGMs) from catalyst scraps, the authors investigated an efficient dissolution process where the material was pretreated by electroless Fe deposition. When Rh-loaded alumina powder was kept in aqua regia at 313 K (40 °C) for 30 to 60 minutes, the Rh hardly dissolved. Meanwhile, after electroless Fe plating using a bath...

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Magnetic Concentration of Platinum Group Metals from Catalyst Scraps Using Iron Deposition Pretreatment

Yu-ki Taninouchi, Tetsuo Watanabe, Toru H. Okabe

Metallurgical and Materials Transactions B > 2017 > 48 > 4 > 2027-2036

Spent automobile catalysts are the most important secondary source of platinum group metals (PGMs). However, effective recovery of PGMs from catalyst scraps is difficult because they are present in only small quantities as chemically stable substances. In this study, in order to improve the efficiency of the existing recycling processes, the authors experimentally investigated a novel physical concentration...

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Electrochemical Deoxidation of Titanium and Its Alloy Using Molten Magnesium Chloride

Yu-ki Taninouchi, Yuki Hamanaka, Toru H. Okabe

Metallurgical and Materials Transactions B > 2016 > 47 > 6 > 3394-3404

Oxygen was directly removed from pure titanium and a Ti-6Al-4V alloy by electrolysis in molten MgCl₂ at 1173 K (900 °C), where the metal being refined was the cathode and a graphite rod was used as the anode. By applying a voltage of approximately 3 V between the electrodes, commercially pure titanium, containing 1200 mass ppm oxygen, and the Ti-6Al-4V alloy, containing 1400 mass ppm oxygen, were...

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Effects of oxygen content and heating rate on phase transition behavior in Bi2(V0.95Ti0.05)O5.475−x

Yu-ki Taninouchi, Tetsuya Uda, Tetsu Ichitsubo, Yasuhiro Awakura, more

Journal of Alloys and Compounds > 2011 > 509 > 19 > 5833-5838

The phase transition behavior of oxide-ion conductor Bi ₂ (V _0.95 Ti _0.05 )O _5.475−x , which has various thermal histories and sample forms, has been studied by means of differential scanning calorimetry. Thermogravimetric analysis revealed that the oxygen content per compositional formula varied with the applied thermal treatment, although no significant structural...

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Phase classification, electrical conductivity, and thermal stability of Bi2(V0.95TM0.05)O5.5+δ (TM: transition metal)

Yu-ki Taninouchi, Tetsuya Uda, Tetsu Ichitsubo, Yasuhiro Awakura, more

Solid State Ionics > 2010 > 181 > 27-28 > 1279-1286

The electrical conductivity and phase transition temperatures of Bi ₂ (V _0.95 TM _0.05 )O _5.5+δ (TM (transition metal) =Ti, Zr, Hf, Nb, Ta, Cr, Mo, and W) were studied by X-ray diffraction analysis, AC impedance spectroscopy, and DC polarization measurements. To understand the changes in electrical conductivity, the structural phases were classified into three groups...

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High oxide-ion conductivity of monovalent-metal-doped bismuth vanadate at intermediate temperatures

Yu-ki Taninouchi, Tetsuya Uda, Tetsu Ichitsubo, Yasuhiro Awakura, more

Solid State Ionics > 2010 > 181 > 15-16 > 719-723

Li- and Ag-doped Bi ₂ VO _5.5 were synthesized by solid-state reactions, and their high oxide-ion conductivities at intermediate temperatures between 400 and 600°C were demonstrated. Li- and Ag-doped Bi ₂ VO _5.5 show a higher symmetry than Bi ₂ VO _5.5 at room temperature. In Bi ₂ (V _0.9 Li _0.1 )O _5.3 and Bi ₂ (V...

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Dehydration of CsH2PO4 at temperatures higher than 260 °C and the ionic conductivity of liquid product

Yu-ki Taninouchi, Tetsuya Uda, Yasuhiro Awakura

Solid State Ionics > 2008 > 178 > 31-32 > 1648-1653

The dehydration of the superprotonic conductor CsH ₂ PO ₄ has been carefully examined above 260 °C under highly humidified conditions. A.C. impedance spectroscopy on heating revealed that the dehydration of CsH ₂ PO ₄ was accompanied by an increase in conductivity, whereas at temperatures below 260 °C, CsH ₂ PO ₄ dehydrates to solid CsPO ₃ with...

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Search results for: Yu-ki Taninouchi

Electrochemical Deoxidation of Titanium in Molten MgCl₂–YCl₃

Deoxidation of Titanium Using Mg as Deoxidant in MgCl₂-YCl₃ Flux

Thermodynamic Analysis of Deoxidation of Titanium Through the Formation of Rare-Earth Oxyfluorides

Dissolution Behavior of Iron and Steel Materials in Liquid Magnesium

Recovery of Platinum Group Metals from Spent Catalysts Using Iron Chloride Vapor Treatment

Thermodynamic Considerations of Direct Oxygen Removal from Titanium by Utilizing the Deoxidation Capability of Rare Earth Metals

Enhanced Dissolution of Platinum Group Metals Using Electroless Iron Deposition Pretreatment

Magnetic Concentration of Platinum Group Metals from Catalyst Scraps Using Iron Deposition Pretreatment

Electrochemical Deoxidation of Titanium and Its Alloy Using Molten Magnesium Chloride

Effects of oxygen content and heating rate on phase transition behavior in Bi2(V0.95Ti0.05)O5.475−x

Phase classification, electrical conductivity, and thermal stability of Bi2(V0.95TM0.05)O5.5+δ (TM: transition metal)

High oxide-ion conductivity of monovalent-metal-doped bismuth vanadate at intermediate temperatures

Dehydration of CsH2PO4 at temperatures higher than 260 °C and the ionic conductivity of liquid product

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