Ryosuke O. Suzuki

Ryosuke O. Suzuki
Hokkaido University | Hokudai · Faculty of Engineering

PhD

About

297
Publications
20,302
Reads
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5,205
Citations
Citations since 2017
80 Research Items
2633 Citations
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
20172018201920202021202220230100200300400500
Introduction
Reduction of Metallic Oxides and CO2 Gas Using Molten Salt Grant-in-Aid for Scientific Research, JST-ALCA Project Year: 1995-2014 Design and Optimization of Thermoelectric Power Generator JST-CREST Project Year: Oct 2008 - Mar 2014
Additional affiliations
April 2021 - present
Science Lab SUZUKI
Position
  • CEO
October 2008 - March 2014
Japan Science and Technology Agency (JST)
Position
  • JST-CREST
March 2006 - March 2021
Hokkaido University
Position
  • Professor (Full)
Education
April 1975 - March 1984
Kyoto University
Field of study
  • Metal Science and Metallurgy

Publications

Publications (297)
Article
To examine the assumption of a constant solidus temperature—which has been empirically adopted in general heat analyses without firm validation—in all solidification stages for multicomponent steels, heat- and solute-transfer equations were simultaneously solved using the finite thickness model, which focuses on early-to-late-stage solidification e...
Article
The H2 generated during the electrolysis of H2O present in molten CaCl2 inhibits metallothermic reduction by metallic Ca. The impact of residual H2O on the cathodic reaction was estimated by electrolyzing H2O-containing CaCl2 at 1173 K in Ar atmosphere using high-speed imaging, which visualized the H2 bubbles occurring around the cathode, to analyz...
Article
Full-text available
Anodizing Al in chromic acid is a very useful surface finishing process for corrosion protection and nanoscale porous structure fabrication, whereas the self-ordering of porous anodic alumina (PAA) in chromic acid has never been found to date. Herein, we provide a self-ordered PAA film possessing numerous sub100-nm-scale characteristic bumps throug...
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Full-text available
Titanium oxide can be converted directly to its metallic state. This extraordinary technology is realized in a CaCl2-based molten salt that can extract oxygen ions from the cathode. Several discussions have been exchanged in the field of electrochemistry and metallurgy in the last two decades. Recent papers on titanium refining are overviewed by se...
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Full-text available
High-aspect ratio ordered nanomaterial arrays exhibit several unique physicochemical and optical properties. Porous anodic aluminum oxide (AAO) is one of the most typical ordered porous structures and can be easily fabricated by applying an electrochemical anodizing process to Al. However, the dimensional and structural controllability of conventio...
Article
The electro-calciothermic reduction of tantalum sulfide (TaS2) was applied to open a new pathway for producing high-purity Ta powders applicable for tantalum electrolytic capacitors. The supplied electric charge was varied to electrochemically reduce the sulfide at 900 °C using Ca in molten CaCl2−xCaS (x = 0.1, 0.5 mol%) salts. The cleaner TaS2 cou...
Article
Full-text available
Silicon sulfide (SiS2) was synthesized from Si, SiC, Si3N4, and a eutectic Al-Si liquid. An Ar-CS2 gas mixture, after bubbling through liquid CS2, was passed over pulverized Si, SiC, Si3N4, or a eutectic Al-Si alloy liquid. White, needle-shaped SiS2 was precipitated as a single phase on the colder downstream surface when Si powder in a SiO2 liner w...
Article
Rapid formation of a porous alumina film without oxide burning was achieved by anodizing in etidronic acid at large current densities using a nanodimpled aluminum surface. After the electropolished aluminum specimens were galvanostatically anodized in a 0.3 M etidronic acid solution at 293 K, a uniform porous alumina film without oxide burning was...
Article
The influence of the nanomorphology of alumina nanowires (ANWs) fabricated by a two-step anodizing process on the superhydrophobicity was investigated through advancing contact angle (ACA) and receding contact angle (RCA) measurements. Aluminum nanobowl specimens were anodized in pyrophosphoric acid to fabricate an ordered ANW structure with an ave...
Article
Anodizing aluminum in a concentrated pyrophosphoric acid solution leads to the formation of numerous anodic alumina nanofibers, and this nanofiber-covered surface shows superhydrophilicity measuring less than 10° in water contact angle. In contrast, as the alumina surface is modified with a self-assembled monolayer (SAM), the surface exhibits super...
Article
Galvanostatic and potentiostatic anodizing processes of aluminum leads to the formation of large-scale porous alumina. It is previously reported that self-ordered porous alumina measuring above 500 nm in cell diameter can be fabricated via two-step anodizing in etidronic acid at higher voltage more than 200 V. On the other hand, extremely little ha...
Article
TiC was examined as a starting material for Ti metal production by sulfidation and electrochemical reduction in molten salt. The sulfur evaporation temperature, sulfidation temperature, and time were optimized in a dual-zone furnace for the efficient and sustainable formation of TiS2 as well as carbon removal from TiC by S2 gas sulfidation. A mixtu...
Article
A new concept for producing highly pure Ti metal powder from ilmenite (FeTiO3) is proposed in this article. Titanium nitride (TiN) or titanium oxycarbonitride (TiOxCyNz) could be synthesized in the first step by the simultaneous carbothermal reduction and nitridation (CTRN) of FeTiO3 to remove oxygen roughly. In order to separate oxygen completely,...
Article
To analyze the complex droplet transient deformation involving two immiscible phases, a practical multi-interfacial tension model has been introduced in the SPH framework. The attraction, which operates on the interface between the different phases is explicitly defined as London dispersion force using the Fowkes theoretical model, and the interfac...
Article
Full-text available
The formation behaviors of the anodic oxide film that forms on various commercially available aluminum plates were investigated by galvanostatic anodizing in etidronic acid, and their corrosion resistances were examined in a 3.5 wt% NaCl solution. High-purity aluminum and A1050, A5052, and A7075 aluminum alloys were galvanostatically anodized in an...
Article
This study attempted to conduct a topological data analysis of groups of particles in packed-bed structures to provide quantitative evaluations of void shapes. This study examined the spatial correlation between the packed bed structure and the holdup sites through geometric data obtained from the coordinates of the various particles composing the...
Article
A simulation of the dripping behavior of solid-phase suspended molten slag in a coke bed was performed using the Bingham fluid model in the framework of smoothed particle hydrodynamics (SPH). SPH can track the motion of droplets which are suspended in dispersed solids. A case study was performed in which the yield coefficient varied with the viscos...
Article
Photoluminescence (PL) emission from anodic aluminum oxide (AAO) formed by etidronic acid anodizing was investigated via fluorescence spectroscopy. Highly pure aluminum plates were anodized in an etidronic acid solution under various operating conditions. PL emission from the typical AAO film was identified with an approximately 250–275-nm range in...
Article
Full-text available
The initial growth of a porous alumina film with a large-scale cell structure formed by galvanostatic anodizing in etidronic acid was investigated in detail by high-resolution microscopy. High-purity aluminum plates were galvanostatically anodized in etidronic acid at 2.5–20.0 Am ⁻² . The formation of an anodic oxide and the subsequent instability...
Article
A plasma electrolytic oxidation (PEO)/anodic aluminum oxide (AAO) multi-layer film was fabricated via one-step galvanostatic anodizing of high-purity aluminum in 0.3–2.0 M ammonium carbonate ((NH4)2CO3) solutions at 283–333 K and 25–400 Am⁻². Anodizing at higher concentrations and higher temperatures caused the formation of relatively uniform anodi...
Article
Full-text available
In the bottom region of blast furnaces during the ironmaking process, the liquid iron and molten slag drip into the coke bed by the action of gravity. In this study, a practical multi-interfacial smoothed particle hydrodynamics (SPH) simulation is carried out to track the complex liquid transient dripping behavior involving two immiscible phases in...
Article
Scandium sulfides were synthesized from its stable oxide, Sc2O3, using CS2 gas. Suitable temperature and time for synthesis were examined experimentally using a constant flow rate of gas mixture of Ar and CS2. The high rate of evaporation from liquid CS2 enhanced formation and stoichiometry of sulfides, and eliminated impurity carbon. Most of parts...
Article
Full-text available
A new metallurgical process via titanium sulfide from ilmenite is proposed and experimentally approved: It consists of several stages; 1) The ilmenite ore is exposed to gaseous CS 2 to selectively sulfurize to FeS, which is wet-chemically removed. 2) The residual oxide is again exposed to CS 2 to form TiS 2 . 3) TiS 2 is electrochemically reduced t...
Article
An in situ observation technique of the TiO2 interfacial behavior in molten LiCl-KCl electrolysis was developed. The variation of the thin TiO2 electrode surface were tracked through the high-speed digital microscopy synchronized with the electrochemical measurement. Two characteristic interfacial behaviors were discovered: physical breakage of the...
Article
This work presents a new processing concept for production of Ti metal powder from FeTiO3via TiN and TiSx. Because FeTiO3 can be converted to TiN by the carbothermal reduction and nitridation method, TiN was taken as the starting material. Ti2.45S4 and TiS2 powders were completely formed from TiN at 1473 K (1200 °C) in 3.6 and 10.8 ks, respectively...
Article
Titanium dioxides were reduced to metallic titanium via molten salt electrolysis using CaCl2. It was reported that the efficiency was low because some side reactions produced carbon precipitates. To produce titanium more efficiently, these electrochemical side reactions were examined by cyclic voltammetry (CV). O²⁻ reacted with the carbon anode to...
Article
Full-text available
A superhydrophilic aluminum surface with fast water evaporation based on nanostructured aluminum oxide was fabricated via anodizing in pyrophosphoric acid. Anodizing aluminum in pyrophosphoric acid caused the successive formation of a barrier oxide film, a porous oxide film, pyramidal bundle structures with alumina nanofibers, and completely bent n...
Article
Anodizing aluminum in a pyrophosphoric acid solution (H 4 P 2 O 7 ) causes the formation of numerous anodic alumina nanofibers. The nanofiber-covered aluminum surface exhibits superhydrophilicity measuring less than 10° in water contact angle (WCA). In contract, as the alumina surface is modified with a self-assembled monolayer (SAM), the WCA value...
Article
Anodizing aluminum in etidronic acid (1-hydroxyethane-1,1-diphosphonic acid) causes the formation of porous alumina at higher voltage more than 200 V. Highly ordered porous alumina with a large-scale cell can be easily fabricated via two-step constant voltage anodizing in etidronic acid. However, extremely little has been reported on the growth beh...
Article
A newly discovered electrolyte for anodizing aluminum, etidronic acid (CH 3 C(OH)[PO(OH) 2 ] 2 ), operates at high voltages of more than 200 V, and ordered porous alumina measuring 400-670 nm in cell diameter (interpore distance) can be fabricated via constant voltage anodizing. Because such porous alumina film formed at high voltages possesses a t...
Article
The transient behavior of the multi-interfacial flow can be modeled using recent Smoothed Particle Hydrodynamics (SPH) model. This developed numerical method is fully-Lagrangian particle-based approach, which can track the movement of many fluid phase directly. The advantage of this simulation model is a direct calculation in both of dispersed phas...
Article
Electrochemical and morphological characterization of the porous alumina formed by galvanostatic anodizing in etidronic acid under various operating conditions was performed. High-purity aluminum plates were anodized in 0.03–3 M etidronic acid solutions at 273–333 K and 0.25–500 Am⁻² for up to 24 h. Galvanostatic anodizing in etidronic acid operate...
Article
The anodizing of aluminum in an alkaline sodium tetraborate (Na2B4O7) solution was investigated with respect to the nanostructural characterization of anodic porous alumina. Electropolished aluminum specimens were galvanostatically anodized under various conditions in 0.1–0.5 M sodium tetraborate solutions at 293–353 K and a current density of 2.5–...
Article
An approximate analytical model has been developed to obtain simultaneous solutions for nonlinear solute- and heat-transfer equations for multi-component alloy steels; in this model, a linear relation between the solid fraction and the temperature in the mushy zone was assumed. This model predicts important parameters, such as the solidus temperatu...
Article
Solubility of CaS in molten CaCl2–65 mol%LiCl eutectic salt was examined by sampling of CaS saturated salt and ICP analysis. The handling in dried environment and an adequate mass of melt were applied for reliable measurements, in addition to suppression of inclusion of CaS particles. The solubility limit was found to be 0.22 ± 0.05, and 0.31 ± 0.0...
Article
In order to check the solubility of CaS during sulfide reduction in molten CaCl2, the mixture of CaCl2 and a small amount of CaS was melted in Ar at the range from 1123 K to 1223 K. The melt was sampled by quartz tube and rapidly solidified. The solidified samples showed a lamella structure with CaS particles, which results in a simple eutectic rea...
Article
Full-text available
The fabrication of sticky and slippery superhydrophobic aluminum was achieved by anodizing in pyrophosphoric acid and modification with self-assembled monolayers (SAMs). In addition, the corresponding sliding behaviors of a water droplet were investigated by contact angle measurements and direct observations. For the formation of anodic alumina nan...
Article
Running footer on this article appeared incorrectly. It should read 644—VOLUME 49B, APRIL 2018. © 2018, The Minerals, Metals & Materials Society and ASM International.
Article
Gold nanoparticles were fabricated on an ordered aluminum dimple array via aluminum anodizing, sputter coating, and thermal treatment, and the transformation behavior and nanostructural characterization were investigated in detail. Electropolished aluminum specimens were anodized in an oxalic acid solution under self-ordering conditions at 40 V, an...
Article
Full-text available
The molten salt-based direct reduction process for reactive solid metal outperforms traditional pyrometallurgical methods in energy efficiency. However, the simplity and rapidity of this process require a deeper understanding of the interfacial morphology in the vicinity of liquid metal deposited at the cathode. For the first time, here we report t...
Article
Anodizing aluminum in a concentrated pyrophosphoric acid solution (H 4 P 2 O 7 ) leads to the formation of numerous anodic alumina nanofibers measuring less than 10 nm in diameter. As the alumina nanofibers are modified with self-assembled monolayer (SAM), the nanofiber-covered aluminum surface exhibits a superhydrophobic behavior with a water cont...
Article
Anodizing aluminum is very important for protecting the aluminum substrate, and anodizing in a sulfuric acid solution at low temperature causes the formation of hard porous alumina with a high Vickers hardness of more than Hv = 300. However, harder porous alumina is required to expand the applicability of porous alumina in various industrial applic...
Article
Left-side elements in periodic table are stable in oxide state. In order to produce their metals from the oxides, the molten CaCl 2 is useful as the media where CaO is dissolved. By applying 3.0 V above melting temperature of CaCl 2 (1045 K), CaO in CaCl 2 melt electrochemically decomposes into metallic Ca and oxygen. The deposited Ca at cathode ca...
Article
Numerical analysis was carried out on the dripping and holdup behaviors in the lower part of a blast furnace for coke bed structures having different shapes; a discrete element method smoothed particle hydrodynamics scheme was used considering the size distribution immediately above the raceway. Even for coke beds with similar void fractions, the a...
Article
We investigated the transient behavior of immiscible two-liquid interfaces initiated by a single rising gas bubble and characterized by liquid “column” and “film” morphologies. To analyze the effect of the buoyancy force, viscosity, and interfacial tension on these morphologies, the single-solution density was controlled continuously by association...
Article
We demonstrate mirror-finished superhydrophobic aluminum surfaces fabricated via the formation of anodic alumina nanofibers and subsequent modification with self-assembled monolayers (SAMs). High-density anodic alumina nanofibers were formed on the aluminum surface via anodizing in a pyrophosphoric acid solution. The alumina nanofibers became tangl...
Article
Previously this group reported that a good quality titanium metal powder can be produced from titanium sulfides by electrochemical OS process. In this study, the sulfurization procedure was examined to synthesize titanium sulfide from titanium oxycarbonitride by CS2 gas. The experiments were carried out in the temperature range of 1173 K to 1523 K...
Article
A 3D scanning technique was applied for understanding coke shapes obtained by a rotational strength test, and a numerical dynamic analysis based on the multi-sphere type discrete element method was carried out to clarify the influence of coke degradation on the packed structure. We constructed a trickle flow simulation of molten slag via the smooth...
Article
The reduction of CaTiO3 to generate Ti powder with a low content of oxygen was examined by electrolysis in a CaCl2- CaO melt. Using various sizes of the raw oxide particles, the concentration profile of the residual oxygen in the cathode basket suggests a reduction mechanism involving calcium from the melt. The residual oxygen content was influence...
Article
An analytical approximate solution to non-linear solute- and heat-transfer equations in the unsteady-state mushy zone of Fe-C plain steel has been obtained, assuming a linear relationship between the solid fraction and the temperature of the mushy zone. The heat transfer equations for both the solid and liquid zone along with the boundary condition...
Article
China’s iron and steel industry has made great progress in energy savings and emission reductions with the application of many waste heat recovery technologies. However, most of the medium and low temperature waste heat and radiant waste heat has not been effectively utilized. This paper proposes a thermoelectric system that generates electricity b...
Article
System design of a thermoelectric (TE) power generation module is pursued in order to improve the TE performance. Square truncated pyramid shaped P–N pairs of TE elements are connected electronically in series in the open space between two flat insulator boards. The performance of the TE module consisting of 2-paired elements is numerically simulat...
Article
A high-resolution numerical model was performed for a detailed understanding of packed-bed structures constructed by actual scale cokes, and the molten slag (SiO2–CaO–Al2O3) trickle flow characteristics in the lower part of an actual blast furnace. Smoothed particle hydrodynamics (SPH) simulations can track the motion of liquids containing disperse...
Article
The fabrication of submicrometer-scale ordered convex lens array was demonstrated through nanoimprint lithography using an aluminum dimple array mold fabricated by etidronic acid anodizing and selective oxide dissolution. Highly-pure aluminum plates were anodized in a 0.2M etidronic acid solution at 260V for the formation of ordered porous alumina....
Article
A fully-Lagrangian numerical model was applied for understanding packed bed structures containing non-spherical solids, such as coke, and the high-temperature melt trickle flow characteristics of such beds. Smoothed-particle hydrodynamics (SPH) simulations can track the motion of liquids without discriminating between continuous and dispersed phase...
Article
Introduction Recently, we demonstrated the fabrication of anodic alumina nanofibers via anodizing in a new electrolyte, pyrophosphoric acid (H 4 P 2 O 7 ). Interestingly, the aluminum surface covered by the anodic alumina nanofibers exhibited a superhydrophilic behavior with a contact angle measuring less than 10°. In the present investigation, we...
Article
In the case of metallothermic reduction of oxide XO x-1 (s) (X=Ti, Ta, etc.) by electro-deposited liquid metal Me(=Ca, Li or their alloys), the it accompanied with dissolved Me at the vicinity of the cathode is essential, where the oxide is placed close to the cathode. In this mechanism, the dissolved Me works effectively to reduce XO x-1 , even if...
Article
Anodizing is one of the most important surface finishing techniques for aluminum and its alloys in various industrial applications. Recently, we reported a novel anodic aluminum oxide formed via anodizing in a new electrolyte, pyrophosphoric acid solution (H 4 P 2 O 7 ). Pyrophosphoric acid anodizing leads to the formation of numerous alumina nanof...
Article
Counter-flowing thermal fluids are conducive to generate a homogeneous temperature difference on thermoelectric (TE) generator. This study allowed the hot and cold fluids of having constant inlet temperature to flow in the opposite, and examined TE performance of module at different flow rates. The results show that TE performance gradually increas...
Article
The fabrication of superhydrophilic and superhydrophobic aluminum alloys was achieved by pyrophosphoric acid anodizing and SAM (self-assembled monolayer) modification. The anodizing of three kinds of aluminum alloys, including 3004, 1N30, and 8021, in a concentrated pyrophosphoric acid solution resulted in the formation of numerous anodic alumina n...
Article
Advanced hard anodic alumina coatings measuring Hv = 610–769 on the Vickers hardness scale were obtained on an aluminum surface via aluminum anodizing using a new electrolyte, etidronic acid. The ordered porous alumina was fabricated by two-step etidronic acid anodizing at 260 V under self-ordering conditions, and pore-widening was carried out to c...
Article
A new branched morphology of metallic niobium powder particles was produced by calciothermic reduction of niobium oxides in molten CaCl2. The influence of some reaction parameters on the powder particle morphology was studied, and the formation mechanism was investigated. It was found that the formation of intermediate complex niobium oxides (CaxNb...
Article
We report the growth of electrochemically deposited liquid lithium droplet in LiCl–KCl–Li2O melt at 673–723 K. To understand the transient behavior of liquid lithium in the electrolyte, the interface between the electrodeposited molten metal phase and the molten salt system was observed in situ using a high-speed digital microscope. We found that t...
Article
Fabrication of a nanoporous tungsten oxide film via anodizing of tungsten in an ammonium nitrate (NH4NO3)/ethylene glycol (EG)/water (H2O) mixture is reported for use as a visible light-driven photocatalyst. Anodizing of tungsten in a 1.0 M NH4NO3/EG solution containing less than 0.1 vol% H2O resulted in active dissolution of the tungsten substrate...
Article
Thermoelectric (TE) performance of a three-dimensional (3-D) TE module is examined by exposing it between a pair of counter-flows of ideal fluids. The ideal fluids are thermal sources of TE module flow in the opposite direction at the same flow rate and generate temperature differences on the hot and cold surfaces due to their different temperature...
Article
We have investigated the details of the calciothermic reduction of TiO2 in CaCl2-CaO-Ca molten salt electrolyte and developed a process for Ti production that is proceeding toward commercialization. In this process, when a potential of 3 V is applied between the carbon anode and the stainless steel cathode, the electrolytic decomposition of CaO occ...
Article
The transient behaviors of two immiscible liquids, namely, molten matte and molten slag, with a high interfacial tension were investigated using the smoothed particle hydrodynamics model. Numerical simulations were performed using a discrete-element-type method that could track the movement of both the continuous liquid phase and the dispersed one...
Article
Anodizing of aluminum in an arsenic acid solution is reported for the fabrication of anodic porous alumina. The highest potential difference (voltage) without oxide burning increased as the temperature and the concentration of the arsenic acid solution decreased, and a high anodizing potential difference of 340 V was achieved. An ordered porous alu...
Article
Metallic vanadium was successfully produced starting from vanadium sulfide by applying electrolysis in molten CaCl2. Vanadium sulfide filled in a cathodic Ti basket and a graphite anode were immersed in the melt of CaCl2-CaS at 1173 K in Ar, and the electrolysis was conducted at a cell voltage of 3.0 V. Sulfide electrolysis did not form carbon depo...
Article
In this study, we reduce TiS2 to Ti via both calciothermic reduction and electrolysis in a CaCl2 melt. Upon calcium reduction at 1133 K in CaCl2 melt, the concentration of sulfur decreases to 0.03 mass% S when an amount greater than twice the stoichiometric calcium amount is added. Upon electrolysis reduction at 1173 K in CaCl2-CaS melt, the concen...
Article
The interfacial behavior between sodium polytungstate solution (SPTS) and silicone oil (SO) due to a single rising bubble was directly observed to investigate the influence of the Eötvös number on the flow characteristics. We found that the transient behavior of the jet under the bubble strongly depended on the SPTS density in the range of 1000–300...
Article
Electrochemical decomposition of CaTiO3 at the cathode was examined in a scheme of titanium metal production from natural deposit, Ilmenite (TiFeO3). Based on the possible precipitation of CaTiO3 from TiFeO3, the electrochemical decomposition of CaTiO3 is here examined using combination of the calciothermic reduction and the electrolysis of CaO in...
Article
Full-text available
The electrochemical decomposition of carbon dioxide to form carbon and oxygen gas in CaCl2-CaO molten salt was studied. A water model experiment was carried out to study the influence of the tip shape of the pipe, the pipe diameter and the wettability of the gas injection pipe on the bubble shape in the molten salt. Bubbles were formed with both a...