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김대성,김종환,Hisayuki Suematsu,Kenta Tanaka,류봉기 대한금속·재료학회 2016 METALS AND MATERIALS International Vol.22 No.2
Pulsed wire discharge using Sn-58 Bi wires was used to synthesize intermetallic Sn-58 Bi compound nanoparticles. We investigate that nanopowder particle size is controlled by voltage and gas atmosphere. A large pulsed current was applied to the alloy wires set between the electrodes in two gas atmosphere such as Ar, N2. We were discussed the results based on the k factor. The k factor means Ec/Ev, where Ec and Ev are the charging energy of the capacitor and the vaporization energy of the wire. Nanoparticles whose composition was close to that of Sn-58 Bi were synthesized under N2 atmosphere and 6 kV voltage. In such conditions, the applied energy to the wire was higher than sublimation energy of the wires. Under the other experimental conditions, other phases such as Bi-rich and Sn-Bi compound phases were detected. The major results in this study demonstrate the synthesis of alloy nano powders by using alloy wire.
신정호,김두인,조홍백,김도형,Hisayuki Suematsu,김광호 한양대학교 세라믹연구소 2014 Journal of Ceramic Processing Research Vol.15 No.2
Ternary Zr-Cu-Mo metallic glass thin films (MGTFs) with various Mo contents were synthesized on Si (100) wafers and AISI 304 stainless steel substrates by a magnetron co-sputtering technique, using Zr64Cu36 and Mo targets in an Ar gas environment. The effects of Mo addition in a binary Zr64Cu36 MGTF were investigated, with regard to the microstructural evolution and mechanical properties of Zr-Cu-Mo thin films. Instrumental analyses, such as EPMA, XRD, and HR-TEM revealed that ZrCu-Mo films with an Mo content below 38 at.% maintained the monolithic amorphous phase structure. However, when Mo content is added above 46 at.%, the Zr-Cu-Mo films begin to have nanocomposite structures of well-distributed Mo2Zr and Mo crystallites embedded in an amorphous matrix. The hardness and elastic modulus of amorphous Zr-Cu-Mo films showed nearly constant values of 10 GPa and 166 GPa, respectively, regardless of their Mo content. As Zr-Cu-Mo films have nanocomposite structures at a Mo content of 52 at.%, their mechanical properties showed increased hardness and elastic moduli of 17 GPa and 240 GPa, respectively. The Mo addition generally reduced the average friction coefficient of the ternary Zr-Cu-Mo thin films regardless of phase structure, which can be attributed to the effect of the Mo addition.
High-Speed Camera Analysis for Nanoparticles Produced by using a Pulsed Wire-Discharge Method
김종환,김대성,류봉기,Hisayuki Suematsu,Kenta Tanaka 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.69 No.1
We investigated the performance of a high-speed camera and the nanoparticle size distribution to quantify the mechanism of synthesized nanoparticle formation in a pulsed wire discharge (PWD) experiment. The Sn-58Bi alloy wire was 0.5 mm in diameter and 32 mm long; it was prepared in the PWD chamber, and the evaporation explosion process was observed by using a high-speed camera. In order to vary the conditions and analyze the mechanisms of nanoparticle synthesis in the PWD, we changed the pressure of the N2 gas in the chamber from 25 to 75 kPa. To synthesize nanoparticles on a nano-scale, we fixed the charging voltage at 6 kV, and the high-speed camera captured pictures at 22,500 frames per second. The experimental results show that the electronic explosion process at different N2 gas pressures can be characterized by using the explosion’s duration and the explosion’s intensity. The experiments at the lowest pressure exhibited a longer explosion duration and a greater intensity. Also, at low pressure, very small nanoparticles with a good dispersion were produced.
Jin Zhang,Ryo Kurosawa,Hisayuki Suematsu,Tadachika Nakayama,김상섭 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.3
We report the synthesis of nickel ferrite nanofibers via an elecrospinning technique particularly using iron (II) acetate as an iron precursor. Nanofibers of a single-phase nickel ferrite with a uniform diameter of ~90nm were successfully synthesized by adopting a properly prepared solution and calcination condition. Indi-vidual nickel ferrite nanofibers synthesized by electrospinning were made up of nanograins of ~20 nm in diameter. In addition, the hysteresis observed in a magnetization measurement confirmed their ferromagnetism,supporting their potential use in magnetic devices. These results demonstrate that the use of iron (II)acetate as an iron precursor is another way to synthesize ferromagnetic nickel ferrite nanofibers.
Kim, Dae Sung,Kim, Jong Hwan,Suematsu, Hisayuki,Tanaka, Kenta,Ryu, Bong Ki American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.10
<P>Nanoscale compound powders of Sn-Bi-Cu were successfully synthesized using pulsed wire discharge (PWD). Sn-Bi-Cu powder is used Pb-free soldering materials at low temperature. When the particle size of the Sn-Bi-Cu synthesized as nano-scale has the advantage of lowering the melting point, improving wettability, and stabilizing reaction interface. In PWD, when a high current is passed through high-density metal wires, the wire explodes because of resistance heating, which forms fine particles or metal vapor. We used two wires, Sn-Bi alloy wires and Cu wires, to obtain three-component nanopowders. A high current was applied to the wires between the electrodes in a N-2 atmosphere. We discuss the results based on the K factor, which is E-C/E-V, where E-C and E-V are the charging energy of the capacitor and the vaporization energy of the wire, respectively. Nanoparticles with three components, Sn-Bi-Cu, were synthesized under N-2 atmosphere at voltages of 4/6 kV. According to the particle-size distributions, the mean particle diameter of the prepared Sn-Bi and Cu nanopowders was 14.56-40.36 nm for each condition. In this study, We successfully three-component nanopowders synthesized and subjected two wires to extreme energies by the PWD method to form a nanopowder by overcoming its limited solid solubility.</P>
( Jong Hwan Kim ),( Dae Sung Kim ),( Hisayuki Suematsu ),( Kenta Tanaka ),( Bong Ki Ryu ) 대한금속재료학회(구 대한금속학회) 2017 대한금속·재료학회지 Vol.55 No.1
We used Sn-58Bi and Cu wires to investigate the effects of variable conditions (such as pressure and wire diameter) on the formation of three-component nanoparticles. In the synthesis of the three-component nanoparticles, pulsed wire discharge was used to sublimate the wires. In this system, the K factor is described as E<sub>c</sub>/E<sub>s</sub>, where E<sub>c</sub> and E<sub>s</sub> are respectively the applied energy and the sublimation energy of the system. Experiments were conducted in a N<sub>2</sub> atmosphere using the following parameters: voltage of 6 kV, pressure of 50-100 kPa, and Cu wire diameters of 0.1 and 0.2 mm. X-ray diffraction and field emission scanning electron microscopy were employed for structural analysis, particle size distribution analysis, collection rate, and composition studies of the nanoparticles. (Received May 4, 2016; Accepted July 12, 2016)
Effect of energy deposition on TiO2 nanosized powder synthesized by pulsed wire discharge
Yoshinori Tokoi,Tsuneo Suzuki,Tadachika Nakayama,Hisayuki Suematsu,Futao Kaneko,Koichi Niihara 한국물리학회 2009 Current Applied Physics Vol.9 No.3
Titanium dioxide (TiO2) nanosized powder was synthesized by pulsed wire discharge (PWD) using Ti wire in O2 gas. The pressure of O2 gas (P) and relative energy (K), which is defined as the ratio of the charged energy of the capacitor to the vaporization energy in the wire, were varied from 10 to 100 kPa and 4.3– 51.9, respectively. The density of the plasma/vapor (Dexp), determined by the maximum volume, was decreased with decreasing P and increasing K as observed by high-speed photography during PWD. Xray diffraction analysis confirmed that the rutile content (CR) was increased from 7 to 84 vol% with decreasing Dexp. The median diameter (D50), determined from scanning electron microscopy, was decreased from 36.5 to 10 nm with decreasing Dexp. Therefore, an increase in CR and decrease in D50 both accompany the decrease in Dexp. Titanium dioxide (TiO2) nanosized powder was synthesized by pulsed wire discharge (PWD) using Ti wire in O2 gas. The pressure of O2 gas (P) and relative energy (K), which is defined as the ratio of the charged energy of the capacitor to the vaporization energy in the wire, were varied from 10 to 100 kPa and 4.3– 51.9, respectively. The density of the plasma/vapor (Dexp), determined by the maximum volume, was decreased with decreasing P and increasing K as observed by high-speed photography during PWD. Xray diffraction analysis confirmed that the rutile content (CR) was increased from 7 to 84 vol% with decreasing Dexp. The median diameter (D50), determined from scanning electron microscopy, was decreased from 36.5 to 10 nm with decreasing Dexp. Therefore, an increase in CR and decrease in D50 both accompany the decrease in Dexp.
Synthesis of Zirconium Carbide Nanosized Powders by Pursed Wire Discharge in Oleic Acid
Kenta Sugashima,Kazuma Suzuki,Tsuneo Suzuki,Hisayuki Suematsu,Koichi Niihara,Tadachika Nakayama 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.2
In this study, we propose novel PWD methods in inert gas mixed organic vapor and organic liquid which work as harmless carbon sources. Metal zirconium wire evaporation by PWD in organic vapor or liquid media was investigated. It was confirmed that in the PWD process using oleic acid liquid, single phase zirconium carbide nanopowders were synthesized by a reaction between Zr vapor and oleic acid. A new method for synthesis of carbide nanopowders was developed using the PWD in organic liquid. Therefore, the present result suggested that PWD method in oleic acid liquids is effective for the synthesis of carbide nanopowders.
The nobel solution process using the extreme energy state for anisotropic structured nanomaterials
Tadachika Nakayama,Takashi Minagawa,Shuntaro Suzuki,Hisayuki Suematsu,Koichi Nihara 한국물리학회 2009 Current Applied Physics Vol.9 No.3
A wide variety of materials have been synthesized using procedures that rely on extremely high-energy densities produced by high temperatures and pressures. Anisotropic silver nanomaterials were synthesized by a process that uses high temperatures and pressures in the liquid phase, replacing conventional vacuum production. Powder forms of light-sensitive silver oxide and silver carbonate were dispersed in water and exposed to 355-nm laser illumination, producing nanosheets with a thickness of 10 nm and areas of tens of ㎛2. These large nanosheets of interest since they can be used as structural components of devices having anisotropic electrical and thermal conductivities. A wide variety of materials have been synthesized using procedures that rely on extremely high-energy densities produced by high temperatures and pressures. Anisotropic silver nanomaterials were synthesized by a process that uses high temperatures and pressures in the liquid phase, replacing conventional vacuum production. Powder forms of light-sensitive silver oxide and silver carbonate were dispersed in water and exposed to 355-nm laser illumination, producing nanosheets with a thickness of 10 nm and areas of tens of ㎛2. These large nanosheets of interest since they can be used as structural components of devices having anisotropic electrical and thermal conductivities.