Papers by Author: Hisayuki Suematsu

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Authors: Jun Inoue, Tadachika Nakayama, Tsuneo Suzuki, Hisayuki Suematsu, Wei Hua Jiang, Koichi Niihara
Abstract: Chromium oxynitride (Cr(N,O)) thin film have been successfully prepared by using pulsed laser deposition. The composition of the thin film was determined to be Cr0.50N0.23O0.28 by Ruthreford backscattering spectroscopy (RBS). The structural analysis was carried out by using X-ray diffraction (XRD), and out-of-plane and in-plane measurements were used to clarify the axial ratio (c/a) of the Cr(N,O) phase. The lattice constants of a and c axes in the Cr(N,O) phase were found to be 0.414 and 0.419 nm, respectively. From these results, the cubic to tetragonal phase change by substitution of the oxygen atoms for nitrogen atoms was confirmed for the crystal Cr(N,O) compounds.
Authors: Y. Tokoi, Tadachika Nakayama, Hisayuki Suematsu, Wei Hua Jiang, K. Yatsui, Koichi Niihara
Abstract: Copper nanosized powders were prepared by pulsed wire discharge (PWD) in N2 gas at low pressure (130 Pa) with high-speed gas puff. The pressure around one of the electrodes was changed to investigate the effect of electrical discharge prevention by gas puff. The peak pressure was changed from 22 kPa to 10 kPa in the gas puff apparatus by changing the distance from an acrylic resin tube and a bottom plate. The energy deposition in the copper wire at 22, 15 and 10 kPa was about 40, 37 and 33 J, respectively. The energy deposition in the wire increased with the increase in pressure around the electrode.
Authors: Tetsuhiko Onda, Kenji Okazaki, Hisayuki Suematsu, H. Yamauchi, Motozo Hayakawa
Authors: Hiroki Asami, Jun Inoue, M. Hirai, Tsuneo Suzuki, Tadachika Nakayama, Hisayuki Suematsu, Wei Hua Jiang, Koichi Niihara
Abstract: Chromium magnesium oxynitride ((Cr,Mg)(N,O)) thin films have been prepared by pulsed laser deposition (PLD) method with changing the surface area ratio of Mg target (SR) from 0 to 100 %. As a result of the analysis by energy dispersive X-ray spectroscopy (EDX), it was found that magnesium content in the total metallic elements (Cr1-x, Mgx) are controlled by changing SR from 0 to 100 % to be the x ranging from 0 to 1.0. Since the crystal structure of main phase in all thin films was found to be NaCl type, the XRD results showed that the thin films were mainly consisted of (Cr,Mg)(N,O). The hardness of (Cr,Mg)(N,O) thin films were increased almost linearly up to SR = 50 %, above which it decreases rapidly. The maximum Vickers hardness (HV) of 3600 was obtained for the thin film which was prepared by SR = 50 %, and the minimum HV of 1650 was obtained for the thin film which was prepared by SR = 100 %.
Authors: Motozo Hayakawa, Takashi Inoue, Jae Hwan Pee, Tetsuhiko Onda, Hisayuki Suematsu, H. Yamauchi
Authors: Tsuneo Suzuki, Jun Inoue, Hiroki Asami, Tomoya Ibi, Tadachika Nakayama, Hisayuki Suematsu, Koichi Niihara
Abstract: Cr-Me-N-O (Me; Ni, Cu and Mg) thin films have been designed and successfully prepared by the pulsed laser deposition (PLD) method. It was found that Me, which form the monoxide MeO, are effective for hardening the Cr(N,O) thin films.
Authors: X.P. Zhu, Tsuneo Suzuki, Hisayuki Suematsu, Wei Hua Jiang, Koichi Niihara
Abstract: Nitriding of titanium was achieved in a vacuum of ~2×10-2 Pa by applying intense pulsed ion beam (IPIB) irradiation. Various phases including ‘pure’ nitrides (e.g. Ti2N, TiN) as well as carbonitrides (e.g. TiC0.3N0.7) were found on the IPIB-irradiated surfaces that depended on the ion beam intensity, shot number, and sample position with respect to the ion beam axis. It was found that the nitrides were preferably produced at moderate beam intensity by which the nitriding depth increased greatly with multi-shot irradiation. No or less nitrides were produced under irradiation of very high intensity or less number of shots. It is demonstrated that the IPIB nitriding process is very efficient even in vacuum where the residual N2 can readily react with melted Ti surfaces under IPIB irradiation. The origin of incorporated C in the nitrides is mainly attributed to the anode material of ion diode used in the IPIB apparatus.
Authors: Ryota Kobayashi, Seigo Nishimura, Tsuneo Suzuki, Tadachika Nakayama, Hisayuki Suematsu, Wei Hua Jiang, Koichi Niihara
Abstract: We have attempted phase identification of carbon nanosized powders prepared by pulsed wire discharge (PWD) to clarify the cooling process of PWD plasma. To prepare the carbon nanosized powders, carbon fibers were discharged in nitrogen gas at 26 – 101 kPa by PWD. Volume fractions of phases in the carbon nanosized powders were analyzed by thermogravimetric analysis and powder X-ray diffraction. The volume fraction of amorphous carbon, which must be formed by quenching of carbon plasma, was increased with increasing nitrogen gas pressure. This result suggested that the cooling rate of PWD plasma increased with increasing ambient gas pressure.
Authors: Seigo Nishimura, Y. Hayashi, Tsuneo Suzuki, Tadachika Nakayama, Hisayuki Suematsu, Wei Hua Jiang, A. Yamazaki, K. Seki, Koichi Niihara
Abstract: A pulsed wire discharge (PWD) apparatus for mass production of nanosized powders was developed. The apparatus had a wire feeder, and could prepare 1.5 g of Cu powder in 200 sec. The mean surface diameter of Cu powder was 86 nm. The particle size distribution of the powder prepared by 100 discharges was increased than that by one discharge. In addition, the median diameter of the powder after the 100 discharges was larger than that by one discharge. A part of the nanosized powders in production chamber of the apparatus would be grown by the deposition of plasma or vapor formed by the next discharge.
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