The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform
Takashi Goto - One of the best experts on this subject based on the ideXlab platform.
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microstructure of zrb2 zrn directionally solidified eutectic composite by Arc Melting
Journal of Asian Ceramic Societies, 2018Co-Authors: Eric Jianfeng Cheng, Hirokazu Katsui, Takashi GotoAbstract:ABSTRACTA ZrB2–ZrN eutectic composite was prepared by Arc-Melting a mixture of ZrB2 and ZrN powders under a N2 atmosphere. The eutectic composition was 48ZrB2–52ZrN (mol%), resulting in a rod-like microstructure comprising hexagonally faceted ZrN single-crystal rods dispersed in a ZrB2 single-crystal matrix. The crystal orientation relationship between the ZrB2 matrix and the ZrN rod was ZrB2 //ZrN{101} and ZrB2 //ZrN . The rod-like eutectic composite had a Vickers hardness of 16.2 GPa.
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Microstructure of ZrB2–ZrN directionally solidified eutectic composite by Arc-Melting
Journal of Asian Ceramic Societies, 2018Co-Authors: Eric Jianfeng Cheng, Hirokazu Katsui, Takashi GotoAbstract:A ZrB2–ZrN eutectic composite was prepared by Arc-Melting a mixture of ZrB2 and ZrN powders under a N2 atmosphere. The eutectic composition was 48ZrB2–52ZrN (mol%), resulting in a rod-like microstr...
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lamellar and rod like eutectic growth of tib2 tic tin composites by Arc Melting
Key Engineering Materials, 2014Co-Authors: Eric Jianfeng Cheng, Hirokazu Katsui, Takashi GotoAbstract:TiB2-TiC, TiB2-TiN and TiB2-TiCxN1-x composites were prepared by Arc-Melting mixtures of TiB2, TiC and TiN powders. 28TiB2-72TiC (mol%) composite showed a lamellar eutectic structure, while 55TiB2-45TiN (mol%) composite with a lamellar structure consisted of TiB2, TiN and TiB. 36TiB2-44TiC-20TiN (mol%) was a quasi-binary eutectic composite having a rod-like structure.
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Dielectric properties of Ba1-xCaxTi2O5 prepared by Arc Melting
MATERIALS TRANSACTIONS, 2009Co-Authors: Xin Yan Yue, Takashi GotoAbstract:b-axis-oriented CaO substituted polycrystalline BaTi2O5 ,B a 1� xCaxTi2O5 (BCT2, x ¼ 0 to 0.10), was prepared by Arc Melting. The dielectric property of BCT2 was investigated by an AC impedance method. The lattice parameters of BCT2 decreased with increasing CaO content in the range up to around x ¼ 0:08. The remnant polarization (Pr) and coercive electric field (Ec) of polycrystalline BCT2 at x ¼ 0:08 were 1:6 � 10 � 2 Cm � 2 and 0:4 � 10 6 Vm � 1 , respectively. The Pr of polycrystalline BCT2 was larger than that of BaTi2O5 (BT2, Pr ¼ 0:9 � 10 � 2 Cm � 2 ), while the Ec of BCT2 was smaller than that of polycrystalline BT2 (Ec ¼ 0:7 � 10 6 Vm � 1 ). The permittivity of BCT2 showed the maximum value of 4950 at x ¼ 0:02 and a Curie temperature (Tc) of 736 K. The Tc of BCT2 decreased from 750 to 665 K with increasing CaO content from 0 to 0.10. [doi:10.2320/matertrans.MRA2008333]
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passive oxidation behavior of zrb2 sic eutectic composite prepared by Arc Melting
Key Engineering Materials, 2008Co-Authors: Rong Tu, Hideroni Hirayama, Takashi GotoAbstract:ZrB2-SiC composites were prepared by Arc Melting using ZrB2 and -SiC powders as raw materials and their oxidation behavior were investigated. The eutectic composition of the ZrB2-SiC system was ZrB2-58.5mol%SiC and the Melting point temperature was about 2570 K. At 1673 K mass gain was observed in the oxidation of ZrB2-SiC eutectic composition and the mass gain rate increased with decreasing Ptot. The oxide scale consisted of an amorphous SiO2 layer, a ZrO2-SiO2 eutectic-like layer and a Si-deficient layer.
Li-jie Guo - One of the best experts on this subject based on the ideXlab platform.
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In situ fabrication of ZrB2–SiC composite with arrayed ZrB2 micro-rods by Arc-Melting
Scripta Materialia, 2012Co-Authors: Zhe Ren, Xi-bao Wang, Tao Huang, Li-jie GuoAbstract:ZrB2–SiC composite with textured microstructure consisting of rod-like ZrB2 grains in the SiC matrix is fabricated from a mixture of Zr, B4C and SiC powders by Arc-Melting. The ZrB2 rods are well aligned and embedded in the SiC matrix with well-combined interfaces. The textured microstructures with micro-rods in the composite are proved to play an important role in improving the strength of the composite and have higher fracture resistance compared with the equiaxed microstructures.
Minoru Isshiki - One of the best experts on this subject based on the ideXlab platform.
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Purification of Hafnium by Hydrogen Plasma Arc Melting
MATERIALS TRANSACTIONS, 2011Co-Authors: Kouji Mimura, Keigo Matsumoto, Minoru IsshikiAbstract:Purification of two kinds of Hf metal, a high-purity Hf (HP-Hf) with 99.7 mass% and a low-purity Hf (LP-Hf) with 98 mass%, by hydrogen plasma Arc Melting (HPAM) has been carried out and the removal behavior of various impurity elements has been examined. Many metallic impurities (Fe, Al, Cr, Cu, Mn, Sn, Ti etc.) in the melted Hf, with higher vapor pressures than that of Hf, were removed to the very low levels by vaporization during HPAM and their removal rates increased with the hydrogen content of plasma Arc. Then, the purity (except for Zr, O, N and C) of LP-Hf and HP-Hf were improved to nearly 99.998% and above 99.999%, respectively, after 60 min of 20%H2+Ar plasma Arc Melting. For the removal of Fe, Al, Cu and Ti from Hf, the refining effect of HPAM under atmospheric pressure was found to be superior to that of EBM under high vacuum. Therefore, HPAM has been confirmed to be a very useful method for the purification of Hf and the dissociated and activated hydrogen atoms formed in the high temperature plasma Arc must play an important role for the unique refining process of HPAM.
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hydrogen effect on refining of mo metal by ar h2 plasma Arc Melting
Materials Letters, 2010Co-Authors: Jae-won Lim, Kouji Mimura, Masahito Uchikoshi, Good-sun Choi, Dai Miyawaki, Sangbae Kim, Minoru IsshikiAbstract:Abstract The refining effect of Ar/Ar–H 2 plasma Arc Melting (PAM) was investigated and the purity of Mo metals was evaluated by glow discharge mass spectrometry (GDMS). Most impurities in the Mo metals except for W were removed by Ar/Ar–H 2 PAM down to a few mass ppm levels, and the purities of respective Mo metals refined by Ar/Ar–20%H 2 PAM were improved up to 4N(99.9943%) and 5N(99.9996%). It is also found that Ar–H 2 PAM provides excellent decarburization, deoxidation, and denitrogenization. This confirmed that the refining effect is chemically induced by activated hydrogen atoms during Ar–H 2 PAM.
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Preparation of High-Purity Cobalt by Anion-Exchange Separation and Plasma Arc Melting
Metallurgical and Materials Transactions B, 2010Co-Authors: Masahito Uchikoshi, Kouji Mimura, Hideka Shibuya, Junichi Imaizumi, Tamás Kékesi, Minoru IsshikiAbstract:High-purity Co was prepared with valence-controlled anion-exchange separation, oxidation refining using plasma Arc Melting, and H_2-Ar plasma Arc Melting on a pilot scale. The result of a laboratory-scale experiment indicated that the slower flow rate is more effective to remove the impurities by anion-exchange separation. However, the separation efficiency is reduced by scaling up the column from the laboratory to pilot scale. The discussion of the decrease in the separation efficiency implies that the distribution coefficient increases as the concentration of the adsorbate is lowered, but a reduced slower flow rate might increase the final purity of Co. In addition to anion-exchange separation, Co oxidation refining using plasma Arc Melting was useful. Consequently, a high-purity Co of 99.9998 pct by mass excluding gaseous elements was prepared, which represents the highest purity reported.
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Refining effect of hydrogen plasma Arc Melting on titanium sponges
Materials Letters, 2010Co-Authors: Kouji Mimura, Jae-won Lim, Masahito Uchikoshi, Good-sun Choi, S.-w. Cho, Minoru IsshikiAbstract:Abstract Hydrogen plasma Arc Melting (HPAM) of commercial Ti sponges (> 99.7%) was examined. Ti sponges had main impurities such as Fe, Al, Cl and Mn. These main impurities could be reduced more efficiently by HPAM than by Ar PAM. Other small amount of impurities also had a tendency of reduction by HPAM. In addition, it was found that each removal degree is attributable to a differential refining effect caused by the difference of initial impurity concentration. For the unique refining effect of HPAM, dissociated and activated hydrogen atoms involved in the high temperature plasma Arc are considered to play an important role in the Melting process.
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Purity evaluation of Ta metal refined by Ar/Ar−H2 plasma Arc Melting
Metals and Materials International, 2008Co-Authors: Jae-won Lim, Kouji Mimura, Good-sun Choi, Minoru IsshikiAbstract:The refining effect of Ar/Ar-H2 plasma Arc Melting (PAM) was investigated and the purity of Ta metals was evaluated by glow discharge mass spectrometry (GDMS). Most impurities in the Ta metals were removed by Ar/Ar-H2 PAM, down to a few mass ppm levels, and the purities of respective Ta metals refined by Ar/Ar-20% PAM were improved up to 5N5 (99.9995 %) and 5N7 (99.99972 %). It was also found that the deoxidation reaction under hydrogen plasma condition is enhanced by a remarkable decrease in the oxygen concentration of the Ta metal refined by Ar-H2 PAM.
Zhe Ren - One of the best experts on this subject based on the ideXlab platform.
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In situ fabrication of ZrB2–SiC composite with arrayed ZrB2 micro-rods by Arc-Melting
Scripta Materialia, 2012Co-Authors: Zhe Ren, Xi-bao Wang, Tao Huang, Li-jie GuoAbstract:ZrB2–SiC composite with textured microstructure consisting of rod-like ZrB2 grains in the SiC matrix is fabricated from a mixture of Zr, B4C and SiC powders by Arc-Melting. The ZrB2 rods are well aligned and embedded in the SiC matrix with well-combined interfaces. The textured microstructures with micro-rods in the composite are proved to play an important role in improving the strength of the composite and have higher fracture resistance compared with the equiaxed microstructures.
Kouji Mimura - One of the best experts on this subject based on the ideXlab platform.
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Purification of Hafnium by Hydrogen Plasma Arc Melting
MATERIALS TRANSACTIONS, 2011Co-Authors: Kouji Mimura, Keigo Matsumoto, Minoru IsshikiAbstract:Purification of two kinds of Hf metal, a high-purity Hf (HP-Hf) with 99.7 mass% and a low-purity Hf (LP-Hf) with 98 mass%, by hydrogen plasma Arc Melting (HPAM) has been carried out and the removal behavior of various impurity elements has been examined. Many metallic impurities (Fe, Al, Cr, Cu, Mn, Sn, Ti etc.) in the melted Hf, with higher vapor pressures than that of Hf, were removed to the very low levels by vaporization during HPAM and their removal rates increased with the hydrogen content of plasma Arc. Then, the purity (except for Zr, O, N and C) of LP-Hf and HP-Hf were improved to nearly 99.998% and above 99.999%, respectively, after 60 min of 20%H2+Ar plasma Arc Melting. For the removal of Fe, Al, Cu and Ti from Hf, the refining effect of HPAM under atmospheric pressure was found to be superior to that of EBM under high vacuum. Therefore, HPAM has been confirmed to be a very useful method for the purification of Hf and the dissociated and activated hydrogen atoms formed in the high temperature plasma Arc must play an important role for the unique refining process of HPAM.
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hydrogen effect on refining of mo metal by ar h2 plasma Arc Melting
Materials Letters, 2010Co-Authors: Jae-won Lim, Kouji Mimura, Masahito Uchikoshi, Good-sun Choi, Dai Miyawaki, Sangbae Kim, Minoru IsshikiAbstract:Abstract The refining effect of Ar/Ar–H 2 plasma Arc Melting (PAM) was investigated and the purity of Mo metals was evaluated by glow discharge mass spectrometry (GDMS). Most impurities in the Mo metals except for W were removed by Ar/Ar–H 2 PAM down to a few mass ppm levels, and the purities of respective Mo metals refined by Ar/Ar–20%H 2 PAM were improved up to 4N(99.9943%) and 5N(99.9996%). It is also found that Ar–H 2 PAM provides excellent decarburization, deoxidation, and denitrogenization. This confirmed that the refining effect is chemically induced by activated hydrogen atoms during Ar–H 2 PAM.
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Preparation of High-Purity Cobalt by Anion-Exchange Separation and Plasma Arc Melting
Metallurgical and Materials Transactions B, 2010Co-Authors: Masahito Uchikoshi, Kouji Mimura, Hideka Shibuya, Junichi Imaizumi, Tamás Kékesi, Minoru IsshikiAbstract:High-purity Co was prepared with valence-controlled anion-exchange separation, oxidation refining using plasma Arc Melting, and H_2-Ar plasma Arc Melting on a pilot scale. The result of a laboratory-scale experiment indicated that the slower flow rate is more effective to remove the impurities by anion-exchange separation. However, the separation efficiency is reduced by scaling up the column from the laboratory to pilot scale. The discussion of the decrease in the separation efficiency implies that the distribution coefficient increases as the concentration of the adsorbate is lowered, but a reduced slower flow rate might increase the final purity of Co. In addition to anion-exchange separation, Co oxidation refining using plasma Arc Melting was useful. Consequently, a high-purity Co of 99.9998 pct by mass excluding gaseous elements was prepared, which represents the highest purity reported.
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Refining effect of hydrogen plasma Arc Melting on titanium sponges
Materials Letters, 2010Co-Authors: Kouji Mimura, Jae-won Lim, Masahito Uchikoshi, Good-sun Choi, S.-w. Cho, Minoru IsshikiAbstract:Abstract Hydrogen plasma Arc Melting (HPAM) of commercial Ti sponges (> 99.7%) was examined. Ti sponges had main impurities such as Fe, Al, Cl and Mn. These main impurities could be reduced more efficiently by HPAM than by Ar PAM. Other small amount of impurities also had a tendency of reduction by HPAM. In addition, it was found that each removal degree is attributable to a differential refining effect caused by the difference of initial impurity concentration. For the unique refining effect of HPAM, dissociated and activated hydrogen atoms involved in the high temperature plasma Arc are considered to play an important role in the Melting process.
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Purity evaluation of Ta metal refined by Ar/Ar−H2 plasma Arc Melting
Metals and Materials International, 2008Co-Authors: Jae-won Lim, Kouji Mimura, Good-sun Choi, Minoru IsshikiAbstract:The refining effect of Ar/Ar-H2 plasma Arc Melting (PAM) was investigated and the purity of Ta metals was evaluated by glow discharge mass spectrometry (GDMS). Most impurities in the Ta metals were removed by Ar/Ar-H2 PAM, down to a few mass ppm levels, and the purities of respective Ta metals refined by Ar/Ar-20% PAM were improved up to 5N5 (99.9995 %) and 5N7 (99.99972 %). It was also found that the deoxidation reaction under hydrogen plasma condition is enhanced by a remarkable decrease in the oxygen concentration of the Ta metal refined by Ar-H2 PAM.
