Faculty Profiles - TAKASU Tomio

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Effect of polyethylene glycol on electrodeposition of zn active metal oxide composites from a particle-free solution Reviewed International journal

Ueda D., Oue S., Takasu T., Nakano H.

Materials Transactions ( The Japan Institute of Metals and Materials ) 61 ( 11 ) 2170 - 2177 2020.09

Language：English Publishing type：Research paper (scientific journal)

Electrodeposition of Zn–Zr and Zn–V oxide composites was performed under galvanostatic conditions at 313 K on unagitated pH 2 sulfate solutions containing Zn2+ and Zr4+ or VO2+ ions and an additive such as polyethylene glycol (PEG). The effects of PEG addition on the co-deposition of Zr and V oxides and their polarization behavior, and on the microstructure of the deposits, were investigated. Although the Zr content in the deposits obtained from the Zn–Zr solution in the absence of PEG was approximately zero, it increased significantly at a current density of above 1000 A·m−2 following the addition of PEG. In the Zn–V solution, the V content in the deposits obtained from 100 to 2000 A·m−2 was higher with PEG than without it. In the presence of PEG, the cathode potential polarized, the rate of hydrogen evolution increased, and the hydrolysis reaction of Zr4+ and VO2+ ions proceeded smoothly, resulting in an increase in the Zr and V content in the deposits. Additionally, the crystal platelets of Zn in the Zn–Zr and the Zn–V oxide films became fine, and the surface coverage of the spongiform Zr and film-like V oxides increased. Furthermore, the corrosion current densities of the Zn–Zr and Zn–V oxide films obtained from the solution with PEG were lower than those from the solution without it. The reduction rate of dissolved oxygen decreased in the films in the presence of PEG, thereby leading to a decrease in the corrosion current density. This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 84 (2020) 50–57.

DOI： 10.2320/matertrans.MT-M2020164

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Effect of Organic Additives on the Electrodeposition Behavior of Zn from an Alkaline Zincate Solution and Its Microstructure Reviewed International journal

Kenta Fukumoto, Satoshi Oue, Yoshiharu Kikuchi, Shinya Akamatsu, Tomio Takasu, Hiroaki Nakano

MATERIALS TRANSACTIONS 61 ( 3 ) 497 - 505 2020.02

Effect of Polyethylene Glycol on Electrodeposition of Zn Active Metal Oxide Composites from a Particle-Free Solution Reviewed

Daiki Ueda, Satoshi Oue, Tomio Takasu, Hiroaki Nakano

Journal of the Japan Institute of Metals and Materials ( The Japan Institute of Metals and Materials ) 84 ( 2 ) 50 - 57 2019.12

Language：English Publishing type：Research paper (scientific journal)

Electrodeposition of Zn–Zr oxide and Zn–V oxide composites was performed under galvanostatic conditions from an unagitated sulfate solution containing Zn2+, Zr4+, or VO2+ ions and an additive such as polyethylene glycol (PEG). The sulfate solution had a pH of 2 and the electrodeposition was performed at 313 K. The effects of PEG on the co-deposition of the Zr oxides and V oxides and their polarization behavior were investigated. Additionally, the effects of PEG on the microstructure of the deposits were investigated. Although the Zr content in the deposits obtained from the Zn–Zr solution without PEG was approximately zero, it increased significantly at a current density above 1000 A m−2 following the addition of PEG. In the Zn–V solution, the V content in the deposits obtained from 100 A m−2 to 2000 A m−2 was higher with PEG than that without PEG. In the presence of PEG, the cathode potential polarized, the rate of hydrogen evolution increased, and the hydrolysis reaction of Zr4+ and VO2+ ions occurred easily. This resulted in the Zr content and V content increasing in the deposits. Additionally, the crystal platelets of Zn in the Zn–Zr oxide film and the Zn–V oxide film became fine, and the surface coverage of the spongiform Zr oxide and the film-like V oxide increased. Furthermore, the corrosion current densities of the Zn–Zr oxide film and the Zn–V oxide film obtained from the solution with PEG were lower than those from the solution without PEG. The reduction reaction of dissolved oxygen decreased in the films with PEG, thereby decreasing the corrosion current density.

DOI： 10.2320/jinstmet.J2019031

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Effect of Organic Additives on Electrodeposition Behavior of Zn from Alkaline Zincate Solution and Its Micro Structure Reviewed

Fukumoto Kenta, Oue Satoshi, Kikuchi Yoshiharu, Akamatsu Shinya, Takasu Tomio, Nakano Hiroaki

Journal of the Japan Institute of Metals and Materials ( The Japan Institute of Metals and Materials ) 83 ( 11 ) 399 - 406 2019.11

Language：Japanese Publishing type：Research paper (scientific journal)

Electrodeposition of Zn was performed on a Fe electrode at a current density of 20-5000 A·m−2 and a charge of 4 × 104 C·m−2 in an unagitated zincate solution containing 0.62 mol·dm−3 of ZnO, 4.0 mol·dm−3 of NaOH and organic additives at 313 K. The effects of organic additives on the deposition behavior of Zn and the microstructure of the deposits were investigated. The films deposited at current densities higher than 1000 A・m−2 from the solution containing additives of a straight-chain polymer composed of quaternary ammonium cation (PQ) and a quaternary ammonium salt with benzene ring (QA) exhibited the gloss. The polarization curve was separated into a partial polarization curve of Zn deposition and that of hydrogen evolution by using the galvanostatic data of Zn deposition. The overpotentials of charge transfer of Zn deposition and that of ZnO22− ions diffusion increased with additions of PQ and QA. The increase in overpotential was remarkable at potential less noble than −1.5 V. Zn deposition reached the diffusion limit of ZnO22− ions at potential less noble than −1.5 V, indicating that the diffusion of ZnO22− ions was greatly suppressed by PQ and QA. With additions of PQ and QA, the C, N and H were co-deposited with Zn, showing that the additives of PQ and QA were incorporated in deposited films. The size of the Zn crystallite decreased with increasing current density. At a high current density of 5000 A・m−2, the crystallite size decreased furthermore with additions of PQ and QA and the film showed the smooth surface. The orientation index of the {1010} plane of Zn deposited from the solution containing PQ and QA increased with current density. The change of the crystallite size and crystal orientation of deposited Zn were explained related to the deposition overpotential.

DOI： 10.2320/jinstmet.J2019027

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Effect of Additives on the Deposition Behavior and Micro Structure of Invar Fe-Ni Alloys with Low Thermal Expansion Electrodeposited from Watt's Solution Reviewed

Fukuda Keisuke, Kashiwa Yuki, Oue Satoshi, Takasu Tomio, Nakano Hiroaki

Tetsu-to-Hagane ( The Iron and Steel Institute of Japan ) 105 ( 10 ) 988 - 997 2019.10

Language：English Publishing type：Research paper (scientific journal)

The electrodeposition of invar Fe-Ni alloy with low thermal expansion was performed at 100-5000 A·m–2 and 105 C·m–2 in agitated Watt's solution containing NiSO4, NiCl2, FeSO4, C3H4O4, C7H4NNaO3S and H3BO3 at 50ºC. With increasing the concentration of malonic acid, the Ni content in deposits decreased at higher current density region than 2000 A·m–2, while it increased at lower current density region than 1000 A·m–2. The current efficiency for alloy deposition decreased with increasing the concentration of malonic acid. The deposits were composed of granular crystals whose size decreased with increasing the concentration of malonic acid. With an addition of saccharin, the Ni content in deposits significantly decreased, and the current efficiency for alloy deposition increased. With an addition of boric acid, the Ni content in deposits somewhat decreased, and the current efficiency for alloy deposition increased. The surface morphology of deposits changed with the current density and an addition of saccharin, and rarely changed with an addition of boric acid. It was found that the morphology depended on the Ni content in deposits. The deposits with Ni content of 29-38 mass% were composed of granular crystals approximately 300 nm in size, while the deposits with Ni content of 41-52 mass% showed the smooth surface consisted of fine crystals. The effects of additives on the Ni content in deposits and current efficiency can be explained by the change of partial polarization curve for Fe and Ni deposition and hydrogen evolution in Fe-Ni alloy deposition.

DOI： 10.2355/tetsutohagane.TETSU-2019-045

Other Link： https://ci.nii.ac.jp/naid/130007719956

Effects of electrolysis conditions on the formation of electrodeposited invar Fe-Ni alloys with low thermal expansion Reviewed International journal

Fukuda K., Kashiwa Y., Oue S., Takasu T., Nakano H.

ISIJ International ( The Iron and Steel Institute of Japan ) 59 ( 9 ) 1632 - 1641 2019.09

Language：English Publishing type：Research paper (scientific journal)

To elucidate the effects of the electrolysis conditions on the formation of electrodeposited invar Fe–Ni alloys with low thermal expansion, Fe–Ni electrodeposition was performed at 10–5000 A·m−2 and 5 × 105 C·m−2 in an agitated solution containing NiSO4, NiCl2, FeSO4, H3BO3, C7H4NNaO3S, and C3H4O4 at 40°C–60°C. In the low-current-density region, the Ni content in the deposits significantly decreased with increasing current density, reached a minimum, and then increased after reaching the diffusion-limiting current density for Fe deposition. With the increasing concentration of FeSO4 in the solution, the Ni content in the deposits decreased in the lower-current-density region, reached a constant at a moderate current density, and then began to increase at higher current density. As a result, the current density range in which the Ni content in the deposits reached a minimum and remained constant became wider with increasing FeSO4 concentration. With the decreasing pH of the solution, since the partial polarization curve for H2 evolution and the total polarization curve shifted to a higher-current-density region, the curve of the Ni content in the deposits as a function of the current density shifted toward a higher current density. The change in the composition of the Fe–Ni alloy deposits because of the electrolysis conditions can be explained by the changes in the total polarization curve and the partial polarization curves for Fe and Ni deposition and H2 evolution.

DOI： 10.2355/isijinternational.ISIJINT-2019-023

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Effects of electrolyte composition and additives on the formation of invar Fe–Ni alloys with low thermal expansion electrodeposited from sulfate bath Reviewed International journal

Kashiwa Y., Nagano N., Takasu T., Kobayashi S., Fukuda K., Nakano H.

ISIJ International ( The Iron and Steel Institute of Japan ) 59 ( 3 ) 514 - 523 2019.03

Language：English Publishing type：Research paper (scientific journal)

The effects of solution composition and additives on the formation of electrodeposited invar Fe–Ni alloys with low thermal expansion were investigated. In all solutions, increasing the current density from 10 A·m−2 significantly decreased the Ni content in the deposits and resulted in anomalous codeposition, in which the electrochemically less noble Fe was preferentially deposited. Further increasing the current density increased the Ni content in the deposits as Fe deposition reached the diffusion limitation of the Fe2+ ions. Increasing the concentration of Fe2+ ions increased the current density required to initiate an increase in the Ni content in the deposits because of increase in the diffusion-limited current density of Fe. With the increasing concentration of malonic acid, the current density region in which Ni deposition was suppressed was extended, and the potential at which Fe deposition reached the diffusion limitation of the Fe2+ ions was shifted to a less noble direction. As a result, the relationship between the Ni content in the deposits and the current density shifted to a higher-current-density region with increasing malonic acid concentration. At malonic acid concentrations above 0.05 mol·dm−3, the current efficiency for alloy deposition was greatly reduced owing to the promotion of hydrogen evolution. The Ni content in the deposits was significantly increased with the addition of thiourea. Boric acid somewhat increased the Ni content in the deposits in the lower-current-density region. In solutions containing both boric acid and saccharin, an invar alloy of 36 mass% Ni was obtained in the wider-current-density region.

DOI： 10.2355/isijinternational.ISIJINT-2018-676

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Effects of Electrolysis Conditions on the Formation of Electrodeposited Invar Fe-Ni Alloys with Low Thermal Expansion Reviewed

Keisuke Fukuda, Yuki Kashiwa, Satoshi Oue, Tomio Takasu, Hiroaki Nakano

Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan ( The Iron and Steel Institute of Japan ) 105 ( 1 ) 55 - 63 2019.01

Language：English Publishing type：Research paper (scientific journal)

To elucidate the effects of electrolysis conditions on the formation of electrodeposited invar Fe-Ni alloys with low thermal expansion, Fe-Ni electrodeposition was performed at 10-5000 A·m–2 and 5×105 C·m–2 in agitated solution containing NiSO4, NiCl2, H3BO3, FeSO4, C7H4NNaO3S and C3H4O4 at 40-60°C. Ni content in deposits significantly decreased in the low current density region with increasing current density, reached a minimum, and then increased due to reaching at diffusion limiting current density for Fe deposition as the current density increased further. With increasing the concentration of FeSO4 in solution, Ni content in deposits decreased at lower current density region, reached a constant at lower current density, and then began to increase at higher current density. As a result, the current density range where Ni content in deposits was minimum and constant became wider with higher concentration of FeSO4. With decreasing pH in solution, since the partial polarization curve for H2 evolution and total polarization curve sifted to higher current density region, Ni content in deposits-current density curve shifted to higher current density region. With stirring the solution, Ni content in deposits reached a minimum as the current density increased, and then began to increase at higher current density than without stirring due to increase in diffusion limiting current density for Fe deposition. The change of the composition in deposits by electrolysis condition can be explained by the changes of the total polarization curve for Fe-Ni alloy deposition and the partial polarization curves for Fe and Ni depositions and H2 evolution.

DOI： 10.2355/tetsutohagane.TETSU-2018-101