研究者データベース

岩井 一彦(イワイ カズヒコ)
工学研究院 材料科学部門 エコマテリアル分野
教授

基本情報

所属

  • 工学研究院 材料科学部門 エコマテリアル分野

職名

  • 教授

学位

  • 博士(工学)

J-Global ID

研究分野

  • ナノテク・材料 / 金属生産、資源生産

職歴

  • -北海道大学 教授
  • 名古屋大学 エコトピア科学研究所 エネルギー科学研究部門 エコトピア科学研究所 エネルギー科学研究部門 准教授

研究活動情報

論文

  • 交流磁場印加下における溶鋼中介在物の浮上挙動
    丸山明日香, 岩井一彦
    鉄と鋼 103 9 499 - 507 2017年 [査読有り][通常論文]
  • Tomoyuki Yokota, Asuka Maruyama, Takashi Yamada, Kazuhiko Iwai
    JOURNAL OF THE JAPAN INSTITUTE OF METALS 81 11 516 - 521 2017年 [査読有り][通常論文]
     
    For clarification of vibrating electromagnetic force effect on concentration boundary layer thickness formed near solid. liquid interface, a metal copper working as an anodic electrode was dissolved into an electrolyte aqueous solution under the imposition of a vibrating electromagnetic force. For its excitation, a current composed of DC and AC components and a static magnetic field were simultaneously imposed on an electrolyte aqueous solution. Because the copper divalent ions concentration is related with brightness of the solution by Lambert. Beer law, brightness of the recorded data using a video camera was directly used for evaluation of the concentration boundary layer thickness formed near the anodic electrode. The concentration boundary layer thicknesses formed under the imposition of the DC current and the static magnetic field, under the imposition of the DC & AC superimposing current without a static magnetic field, and under the imposition of the DC current without a static magnetic field were almost the same, while that formed under the imposition of the DC & AC superimposing current and the static magnetic field was thinner in comparison with the other three conditions. Hydrodynamic instability induced by the vibrating electromagnetic force through a large velocity gradient when the DC & AC superimposing current and the static magnetic field were imposed on the solution might be the reason of the thinner concentration boundary layer. This might be a new tool for controlling mass transfer rate in a concentration boundary layer.
  • 振動電磁場の印加による導電性液体中の非導電性粒子間の衝突促進
    丸山明日香, 岩井一彦
    鉄と鋼 102 3 113 - 118 2016年 [査読有り][通常論文]
  • 振動電磁場の印加下における導電性流体中の非導電性粒子挙動に及ぼすバセット力の影響
    丸山明日香, 岩井一彦
    鉄と鋼 102 3 113 - 118 2016年 [査読有り][通常論文]
  • 電磁振動が合金の偏析に及ぼす影響
    村上史展, 丸山明日香, 岩井一彦
    鉄と鋼 102 3 164 - 169 2016年 [査読有り][通常論文]
  • 電磁振動流を特徴づける無次元パラメータ
    上野和之, 岩井一彦, 嶋﨑 真一
    鉄と鋼 102 3 134 - 140 2016年 [査読有り][通常論文]
  • 振動電磁気力を印加したときにアノード近傍で形成される濃度境界層の直接観察
    横田智之, 丸山明日香, 山田隆志, 岩井一彦
    鉄と鋼 102 3 118 - 126 2016年 [査読有り][通常論文]
  • デンドライトまわりの電磁振動流と溶質輸送の数値解析
    上野和之, 棗千修, 嶋﨑真一, 岩井一彦, 大笹憲一
    鉄と鋼 102 3 141 - 150 2016年 [査読有り][通常論文]
  • アノード反応で形成された濃度境界層に及ぼす超音波の影響
    山角宥貴, 山田隆志, 岩井一彦
    鉄と鋼 102 3 127 - 133 2016年 [査読有り][通常論文]
  • Yi Yuan, Qiang Wang, Kazuhiko Iwai, Donggang Li, Tie Liu, Jicheng He
    JOURNAL OF ALLOYS AND COMPOUNDS 560 127 - 131 2013年05月 [査読有り][通常論文]
     
    Isothermal heat treatment experiments of an Al-4.8mass%Cu alloy were carried out under different magnetic field intensities, at different temperatures and for different holding times. The influence of high magnetic fields on area fraction of theta phase in the solidified microstructure was investigated. It was found that the area fraction of the theta phase was lower when imposing the magnetic field compared to samples heat-treated without magnetic field. In other words, the magnetic field accelerated the phase transformation to the equilibrium state. In addition, the area fraction of the theta phase was independent of magnetic field intensity. This effect of high magnetic fields on the decreasing of the theta phase was discussed from the viewpoint of the effect of high magnetic fields on diffusion. (C) 2013 Elsevier B.V. All rights reserved.
  • Tie Liu, Yin Liu, Qiang Wang, Kazuhiko Iwai, Pengfei Gao, Jicheng He
    Journal of Physics D: Applied Physics 46 12 2013年03月27日 [査読有り][通常論文]
     
    The microstructure evolution and magnetization and magnetostriction properties of Tb0.3Dy0.7Fe1.95 alloy solidified in a high magnetic field were investigated. A cellular microstructure was produced, with the grains highly aligned along the direction of the magnetic field. The (Tb,Dy)Fe2 phase was highly oriented, with its 1 1 1 axis along the magnetic field direction. The easy magnetization direction of the alloy lay along the magnetic field direction. The magnetostriction at room temperature significantly increased to double that of the sample prepared without high magnetic field in addition, a sharp rise in the initial magnetostriction at low fields was observed. Applying a high magnetic field during the solidification process is proposed as an effective route for fabricating 1 1 1 oriented Tb-Dy-Fe compounds, and improving their magnetic and magnetostrictive properties. © 2013 IOP Publishing Ltd.
  • 鈴木悠, 岩井一彦
    鉄と鋼 99 2 156 - 160 2013年 [査読有り][通常論文]
  • 鈴木悠, 岩井一彦
    鉄と鋼 99 2 161 - 166 2013年 [査読有り][通常論文]
  • Structure Modification of Alloy Solidified with Electromagnetic Field
    IWAI Kazuhiko, KOHAMA Takenori, NISHIMURA Tomohiro
    Journal of Iron and Steel Research International 19 203 - 207 2012年 [査読有り][通常論文]
  • Synthesis of Magnetically Intensified Aluminosilicate
    IWAI Kazuhiko, ASANO Makoto, HAGIO Takeshi
    Journal of Iron and Steel Research International 19 327 - 330 2012年 [査読有り][通常論文]
  • Kazuhiko Iwai, Keisuke Kumazawa, Ippei Furuhashi
    ISIJ INTERNATIONAL 51 11 1825 - 1830 2011年 [査読有り][通常論文]
     
    For the clarification of falling behavior of an electrically insulating spherical second phase in the vicinity of a wall under the imposition of a horizontal static magnetic field, distance between the wall and a falling Polytetrafluoroethylene spherical ball in a saturated sodium chloride aqueous solution was observed under the imposition of the horizontal magnetic field where magnetic field intensity and its direction, and electrical conductivity of the wall were chosen as experimental parameters. The obtained distances were statistically analyzed. As the results, the distance when the horizontal magnetic field direction was parallel to the wall, and the distance when the wall was electrically insulating, were the same with the distance when the magnetic field was not imposed. On the other hand, the distance was smaller than the distance when the magnetic field direction was perpendicular to the electrically conductive wall.
  • Yi Yuan, Kazuhiko Iwai, Qiang Wang, Toshiya Matsuzaki, Kai Wang, Ji-cheng He
    ISIJ INTERNATIONAL 51 11 1819 - 1824 2011年 [査読有り][通常論文]
     
    Cu-11 mass% Fe alloy samples were solidified with and without a high magnetic field. The influence of a high magnetic field and cooling rate on the morphology, alignment and distribution of primarily precipitated Fe-rich phase has been investigated. We found that the primary phase of Fe-rich was equiaxed dendrites or columnar dendrites under the combinations effect of magnetic field and initial cooling rate. And Fe-rich primary phase with random alignment was mainly observed in the upper region of the sample solidified without the magnetic field. In the case of the sample solidified with the magnetic field of 7.5 T, however, Fe-rich phase was uniformly distributed and the Fe-rich phase at some areas was aligned parallel to the direction of the magnetic field. Furthermore, slower cooling rate was beneficial to the alignment but was not to the uniform distribution. These phenomena were well discussed from the viewpoint of magnetic shape anisotropy and convection under the high magnetic field.
  • Kazuhiko Iwai
    JAPANESE JOURNAL OF APPLIED PHYSICS 49 12 2010年 [査読有り][通常論文]
     
    The alignment behavior of a crystal with a magnetic anisotropy of chi(c) < chi(a) under the imposition of a rotating magnetic field has been investigated by numerical calculation. The promotion of the crystal alignment when the projection of the magnetically hard axis on the magnetic field rotating plane is parallel to the magnetic field direction and its suppression when the magnetically hard axis is perpendicular to the magnetic field direction can be explained by the fact that the direction of the driving torque acting on the crystal minimizes the magnetic energy. Non dimensional alignment time normalized by the alignment time under the imposition of a static field is constant in the out-of-step region where the crystal cannot follow the magnetic field rotation during its alignment. The initial phase difference between the projection of the magnetically hard axis on the magnetic field rotating plane and its direction hardly affects the alignment time in the out-of-step region but strongly affects that in the synchronous region where the crystal rotation synchronous with the magnetic field rotation. A crystal aligns quickly if the initial phase difference is between 0 and 90 degrees in the synchronous region. The minimum alignment time is the same as that under the imposition of a static field. (C) 2010 The Japan Society of Applied Physics

書籍

  • 「自然に学ぶ材料プロセッシングの創成」
    三共出版 2007年

その他活動・業績

  • ハイドロキシアパタイトの磁場中プロセシング
    金属 80 (5) 373 -377 2010年 [査読無し][通常論文]
  • 熊澤 圭祐, 古橋 一平, 岩井 一彦 実験力学 10 (2) 198 -202 2010年 [査読無し][通常論文]
  • Kazuhiko Iwai, Takenori Kohama ISIJ INTERNATIONAL 50 (2) 187 -190 2010年 [査読無し][通常論文]
     
    A S45C carbon steel has been solidified under the simultaneous imposition of a static magnetic field in vertical direction and an alternating current having a horizontal component. Thus, an electromagnetic force was excited in the sample and it affected structure formation during the solidification. The samples solidified under the different electromagnetic conditions were cut and chemically etched for the observation of the macro- and micro-structures. And those were compared each other. Without the imposition of the static magnetic field and the alternating current on the steel, micro-structure was dendrites. On the other hand, the solidified structure under the imposition of the 1 T static magnetic field and the alternating current of 80 A, 2 kHz was equi-axed structure. When the magnetic field intensity was decreased to 0.3 T some parts of the solidified structure were equi-axed structure. As the frequency of the 80 A alternating current decreased under the constant magnetic field intensity of 1 T, the solidified structure changed from dendritic structure to equi-axed structure. Grain refinement mechanism is supposed to be breaking dendrites into pieces by convection induced in the sample by the non-uniform distribution of the electromagnetic force, which was intensified as the frequency of the electric current increased.
  • ISIJ International 50 (10) 1357–1361 2010年 [査読無し][通常論文]
  • 岩井 一彦, 小浜 丈典 鉄と鋼 96 (11) 637 -640 2010年 [査読無し][通常論文]
  • Kazuhiko Iwai, Takenori Kohama ISIJ INTERNATIONAL 50 (2) 187 -190 2010年 [査読無し][通常論文]
     
    A S45C carbon steel has been solidified under the simultaneous imposition of a static magnetic field in vertical direction and an alternating current having a horizontal component. Thus, an electromagnetic force was excited in the sample and it affected structure formation during the solidification. The samples solidified under the different electromagnetic conditions were cut and chemically etched for the observation of the macro- and micro-structures. And those were compared each other. Without the imposition of the static magnetic field and the alternating current on the steel, micro-structure was dendrites. On the other hand, the solidified structure under the imposition of the 1 T static magnetic field and the alternating current of 80 A, 2 kHz was equi-axed structure. When the magnetic field intensity was decreased to 0.3 T some parts of the solidified structure were equi-axed structure. As the frequency of the 80 A alternating current decreased under the constant magnetic field intensity of 1 T, the solidified structure changed from dendritic structure to equi-axed structure. Grain refinement mechanism is supposed to be breaking dendrites into pieces by convection induced in the sample by the non-uniform distribution of the electromagnetic force, which was intensified as the frequency of the electric current increased.
  • ISIJ International 50 (10) 1357–1361 2010年 [査読無し][通常論文]
  • Kazuhiko Iwai, Masahiro Niimi, Takenori Kohama Japanese Journal of Applied Physics 48 (10) 106503 2009年10月 [査読無し][通常論文]
     
    The alignment behavior of a crystal has been investigated by numerical calculation and an in situ observation experiment with a process combining magnetic field imposition and sample rotation to form unidirectionally aligned crystals with a magnetic anisotropy of chi(c) < chi(a) The experimentally observed alignment behavior of a polymeric fiber and its alignment time agreed with the numerically calculated ones. Crystal alignment under the out-of-step condition alternately repeats the alignment duration and the keeping of a constant duration, and finally the crystal aligns in a specific direction. The alignment time under the synchronous condition is longer than that under the out-of-step condition if the magnetic field intensity is constant. To reduce the alignment time, a strong magnetic field under the out-of-step condition is desirable in this process. (C) 2009 The Japan Society of Applied Physics
  • Kazuhiko Iwai, Masahiro Niimi, Takenori Kohama JAPANESE JOURNAL OF APPLIED PHYSICS 48 (10) 106503 2009年10月 [査読無し][通常論文]
     
    The alignment behavior of a crystal has been investigated by numerical calculation and an in situ observation experiment with a process combining magnetic field imposition and sample rotation to form unidirectionally aligned crystals with a magnetic anisotropy of chi(c) < chi(a) The experimentally observed alignment behavior of a polymeric fiber and its alignment time agreed with the numerically calculated ones. Crystal alignment under the out-of-step condition alternately repeats the alignment duration and the keeping of a constant duration, and finally the crystal aligns in a specific direction. The alignment time under the synchronous condition is longer than that under the out-of-step condition if the magnetic field intensity is constant. To reduce the alignment time, a strong magnetic field under the out-of-step condition is desirable in this process. (C) 2009 The Japan Society of Applied Physics
  • Jun Du, Kazuhiko Iwai MATERIALS TRANSACTIONS 50 (6) 1467 -1476 2009年06月 [査読無し][通常論文]
     
    An alternating current (AC) was imposed upon the hypereutectic Mg-Si melt during solidification to modify the primary Mg2Si crystals in the fixed temperature range between 700 and 630 degrees C. The effects of current intensity and frequency have been investigated in the present study. For every sample, 200 primary Mg2Si crystals were measured and 200 data were then statistically analyzed. The average size and standard deviation were used to evaluate the modification effect, including the refinement and uniformity of sizes of the modified primary Mg2Si crystals. The results show that both frequency and current intensity were significant to determine the modification effect. When the current intensity was fixed at 60 A, the average size increased and uniformity of sizes of the primary Mg2Si crystals improved with the increase in the frequency to 2 kHz. However, in the case that the frequency was fixed at I kHz, the statistical average size increased and uniformity of sizes improved with the increase in the current intensity to 60 A. With the further increase in the current intensity to 90 A, the statistical average size and uniformity of sizes had no obvious changes. The average size drastically decreased and uniformity of sizes remarkably improved with the increase in the estimated electromagnetic force to a critical value of about 126 Nm(-3), Corresponding to the current intensity of 60 A and frequency of I kHz. However, the average size was constant if the electromagnetic force exceeded the critical value. [doi:10.2320/matertrans.MRA2008443]
  • Kazuhiko Iwai, Jun Wan MATERIALS TRANSACTIONS 50 (6) 1493 -1498 2009年06月 [査読無し][通常論文]
     
    We imposed an alternating current on a commercially used aluminum alloy to control its solidified structure. It was applied in the initial stage of the solidification in a static system and during pouring from the tundish to the mold in a flowing system. In the static system, the solidified structure around the electrodes changed from a dendritic structure to an equi-axed one by imposing the current. However, equi-axed structure was not observed at the bottom of the vessel because the primary solid particles in the liquid phase remelted by the sedimentation to a relatively high temperature region. In the flowing system, the solidified structure was also modified from a dendritic structure to an equi-axed structure by imposing the alternating current except for the finally solidified region. The reason why the dendritic structure was obtained at the finally solidified region is that the current did not flow in the metal because of the discontinuous melt dripping in the pipe between the tundish and the mold in the last stage of the pouring. Therefore, it has been confirmed that imposition of the alternating current on the aluminum alloy during its solidification is a useful tool for modification of the structure from dendritic to equi-axed structures. [doi:10.2320/matertrans.M2009012]
  • Jun Du, Kazuhiko Iwai MATERIALS TRANSACTIONS 50 (6) 1467 -1476 2009年06月 [査読無し][通常論文]
     
    An alternating current (AC) was imposed upon the hypereutectic Mg-Si melt during solidification to modify the primary Mg2Si crystals in the fixed temperature range between 700 and 630 degrees C. The effects of current intensity and frequency have been investigated in the present study. For every sample, 200 primary Mg2Si crystals were measured and 200 data were then statistically analyzed. The average size and standard deviation were used to evaluate the modification effect, including the refinement and uniformity of sizes of the modified primary Mg2Si crystals. The results show that both frequency and current intensity were significant to determine the modification effect. When the current intensity was fixed at 60 A, the average size increased and uniformity of sizes of the primary Mg2Si crystals improved with the increase in the frequency to 2 kHz. However, in the case that the frequency was fixed at I kHz, the statistical average size increased and uniformity of sizes improved with the increase in the current intensity to 60 A. With the further increase in the current intensity to 90 A, the statistical average size and uniformity of sizes had no obvious changes. The average size drastically decreased and uniformity of sizes remarkably improved with the increase in the estimated electromagnetic force to a critical value of about 126 Nm(-3), Corresponding to the current intensity of 60 A and frequency of I kHz. However, the average size was constant if the electromagnetic force exceeded the critical value. [doi:10.2320/matertrans.MRA2008443]
  • Kazuhiko Iwai, Jun Wan MATERIALS TRANSACTIONS 50 (6) 1493 -1498 2009年06月 [査読無し][通常論文]
     
    We imposed an alternating current on a commercially used aluminum alloy to control its solidified structure. It was applied in the initial stage of the solidification in a static system and during pouring from the tundish to the mold in a flowing system. In the static system, the solidified structure around the electrodes changed from a dendritic structure to an equi-axed one by imposing the current. However, equi-axed structure was not observed at the bottom of the vessel because the primary solid particles in the liquid phase remelted by the sedimentation to a relatively high temperature region. In the flowing system, the solidified structure was also modified from a dendritic structure to an equi-axed structure by imposing the alternating current except for the finally solidified region. The reason why the dendritic structure was obtained at the finally solidified region is that the current did not flow in the metal because of the discontinuous melt dripping in the pipe between the tundish and the mold in the last stage of the pouring. Therefore, it has been confirmed that imposition of the alternating current on the aluminum alloy during its solidification is a useful tool for modification of the structure from dendritic to equi-axed structures. [doi:10.2320/matertrans.M2009012]
  • Akbar Eskandarpour, Kazuhiko Iwai, Shigeo Asai IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 19 (2) 84 -95 2009年04月 [査読無し][通常論文]
     
    Due to the development of superconducting magnets, the magnetic filtration process is now undergoing its biggest evolution since its conception. In Japan, the first industrial superconducting magnetic filter has been successfully applied for factory wastewater treatment. Much effort in both theory and practice is needed to further contribute to the new developments of this high gradient magnetic filtration process. In this substantial review, we have collected the most important theoretical and practical data about magnetic filtration, its recovery and design to establish a good framework for further development of this amazing technology.
  • Takeshi Hagio, Tomohiko Tanase, Jun Akiyama, Masanori Umino, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 50 (4) 734 -739 2009年04月 [査読無し][通常論文]
     
    Hydroxyapatite ceramic has been demonstrated to be in appropriate material for biomedical applications owing to its bioactivity and high biocompatibility. It has an anisotropic crystal structure that belongs to the hexagonal system. and two types of crystal planes mainly appear on its crystal, which are a-plane and c-plane. Since these two crystal planes are very different in atomic elements. numbers and arrangements. they exhibit different nature (anisotropy). For this reason. it is said that crystal orientation might be intensifying its bioactivity and biocompatibility. However, the differences in biological features on these two crystal planes are not fully clarified yet. In this Study, we have conducted an assessment to reveal anisotropic biological features of hydroxyapatite by Using hydroxyapatite ceramics with controlled orientation fabricated by Slip casting under a magnetic field. Tanase et al. have recently reported the difference in bioactivity on the two crystal plane,; by immersing crystal oriented hydroxyapatitc ceramics into the simulated body fluid and found that c-plane oriented hydroxyapatite ceramics formed a precipitate layer earlier and thicker on its surface compared to a-plane oriented one. We first carried out Welch's t-test on the difference in the thickness of the precipitate layer, reported previously to reveal the difference in bioactivity. Secondly, we conducted an osteoblast culture experiment on hydroxyapatite ceramics with controlled orientation to reveal the difference in initial cell attachment and cell morphology on the two crystal planes of hydroxyapatite using optical microscope observations. In the former case, the results of the Welch's t-test indicated that the thickness of the precipitate significantly differed on each crystal oriented hydroxyapatite ceramics (P < 0.05). In the latter case, initial cell attachment seemed to be better on the a-plane Oriented hydroxyapatitc ceramics and also the morphology of the osteoblasts seemed to be rounded on the a-plane oriented hydroxyapatite ceramics compared to the c-plane oriented one. [doi: 10.2320/matertrans.MBW200836]
  • Akbar Eskandarpour, Kazuhiko Iwai, Shigeo Asai IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 19 (2) 84 -95 2009年04月 [査読無し][通常論文]
     
    Due to the development of superconducting magnets, the magnetic filtration process is now undergoing its biggest evolution since its conception. In Japan, the first industrial superconducting magnetic filter has been successfully applied for factory wastewater treatment. Much effort in both theory and practice is needed to further contribute to the new developments of this high gradient magnetic filtration process. In this substantial review, we have collected the most important theoretical and practical data about magnetic filtration, its recovery and design to establish a good framework for further development of this amazing technology.
  • Takeshi Hagio, Tomohiko Tanase, Jun Akiyama, Masanori Umino, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 50 (4) 734 -739 2009年04月 [査読無し][通常論文]
     
    Hydroxyapatite ceramic has been demonstrated to be in appropriate material for biomedical applications owing to its bioactivity and high biocompatibility. It has an anisotropic crystal structure that belongs to the hexagonal system. and two types of crystal planes mainly appear on its crystal, which are a-plane and c-plane. Since these two crystal planes are very different in atomic elements. numbers and arrangements. they exhibit different nature (anisotropy). For this reason. it is said that crystal orientation might be intensifying its bioactivity and biocompatibility. However, the differences in biological features on these two crystal planes are not fully clarified yet. In this Study, we have conducted an assessment to reveal anisotropic biological features of hydroxyapatite by Using hydroxyapatite ceramics with controlled orientation fabricated by Slip casting under a magnetic field. Tanase et al. have recently reported the difference in bioactivity on the two crystal plane,; by immersing crystal oriented hydroxyapatitc ceramics into the simulated body fluid and found that c-plane oriented hydroxyapatite ceramics formed a precipitate layer earlier and thicker on its surface compared to a-plane oriented one. We first carried out Welch's t-test on the difference in the thickness of the precipitate layer, reported previously to reveal the difference in bioactivity. Secondly, we conducted an osteoblast culture experiment on hydroxyapatite ceramics with controlled orientation to reveal the difference in initial cell attachment and cell morphology on the two crystal planes of hydroxyapatite using optical microscope observations. In the former case, the results of the Welch's t-test indicated that the thickness of the precipitate significantly differed on each crystal oriented hydroxyapatite ceramics (P < 0.05). In the latter case, initial cell attachment seemed to be better on the a-plane Oriented hydroxyapatitc ceramics and also the morphology of the osteoblasts seemed to be rounded on the a-plane oriented hydroxyapatite ceramics compared to the c-plane oriented one. [doi: 10.2320/matertrans.MBW200836]
  • Jun Du, Kazuhiko Iwai MATERIALS TRANSACTIONS 50 (3) 562 -569 2009年03月 [査読無し][通常論文]
     
    The effect of application alternating Current on the modification of primary Mg2Si crystals in the hypereutectic Mg-4.8 mass%Si alloy has been investigated in the present study. The liquidus and eutectic temperatures of the Mg-4.8 mass%Si alloy are 761 degrees C and 638 degrees C, respectively. An alternating current of 60 A with frequency of 1 kHz was applied into the hypereutectic Mg-Si melt from different starting temperatures (770, 740, 700 and 670 degrees C) till 630 degrees C. The results show that primary Mg2Si crystals could be refined effectively by application alternating current. The average sizes of primary Mg2Si crystals were decreased to almost a half after being subjected to the alternating cur-rent. The starting temperature of the application alternating current is a very significant factor to determine the size uniformity of the primary Mg2Si crystals, while it has no obvious effect on the average size of the primary Mg2Si crystals. The refined primary Mg2Si crystals have the lowest average size and the highest uniformity in sizes when the hypereutectic Mg-Si melt was treated by application alternating current from the starting temperature of 700 degrees C. [doi:10.2320/matertrans.MRA2008235]
  • Jun Du, Kazuhiko Iwai MATERIALS TRANSACTIONS 50 (3) 622 -630 2009年03月 [査読無し][通常論文]
     
    An alternating current (AC) of 60 A with a frequency of 1 kHz was imposed on the hypereutectic Mg-4.8 mass% Si melt during solidification in order to modify the primary Mg2Si crystals. The liquidus and eutectic temperatures of the Mg-4.8 mass% Si alloy are 761 degrees C and 638 degrees C, respectively. In order to investigate the effect of temperature ranges with application of AC on the modification of the primary Mg2Si crystals, six temperature ranges from 770 degrees C to 740, 700 and 630 degrees C, and from 700 degrees C to 680, 650 and 630 degrees C were adopted. The temperature ranges examined had an obvious influence on the modification of the primary Mg2Si crystals. For a starting temperature of 770 degrees C, the average size of the primary Mg2Si crystals could be significantly reduced with further decrease in the ending temperature to 700 and 630 degrees C, with agglomeration of the refined primary Mg2Si crystals in these two samples was observed. For a starting temperature of 700 degrees C, the average sizes of the primary Mg2Si crystals could also be reduced, although no obvious agglomeration of the refined primary Mg2Si crystals was observed. The sample treated in the temperature range between 700 and 630 degrees C had primary Mg2Si crystals with the lowest average size and the highest uniformity of size. [doi:10.2320/matertrans.MRA2008366]
  • Jun Du, Kazuhiko Iwai MATERIALS TRANSACTIONS 50 (3) 562 -569 2009年03月 [査読無し][通常論文]
     
    The effect of application alternating Current on the modification of primary Mg2Si crystals in the hypereutectic Mg-4.8 mass%Si alloy has been investigated in the present study. The liquidus and eutectic temperatures of the Mg-4.8 mass%Si alloy are 761 degrees C and 638 degrees C, respectively. An alternating current of 60 A with frequency of 1 kHz was applied into the hypereutectic Mg-Si melt from different starting temperatures (770, 740, 700 and 670 degrees C) till 630 degrees C. The results show that primary Mg2Si crystals could be refined effectively by application alternating current. The average sizes of primary Mg2Si crystals were decreased to almost a half after being subjected to the alternating cur-rent. The starting temperature of the application alternating current is a very significant factor to determine the size uniformity of the primary Mg2Si crystals, while it has no obvious effect on the average size of the primary Mg2Si crystals. The refined primary Mg2Si crystals have the lowest average size and the highest uniformity in sizes when the hypereutectic Mg-Si melt was treated by application alternating current from the starting temperature of 700 degrees C. [doi:10.2320/matertrans.MRA2008235]
  • Jun Du, Kazuhiko Iwai MATERIALS TRANSACTIONS 50 (3) 622 -630 2009年03月 [査読無し][通常論文]
     
    An alternating current (AC) of 60 A with a frequency of 1 kHz was imposed on the hypereutectic Mg-4.8 mass% Si melt during solidification in order to modify the primary Mg2Si crystals. The liquidus and eutectic temperatures of the Mg-4.8 mass% Si alloy are 761 degrees C and 638 degrees C, respectively. In order to investigate the effect of temperature ranges with application of AC on the modification of the primary Mg2Si crystals, six temperature ranges from 770 degrees C to 740, 700 and 630 degrees C, and from 700 degrees C to 680, 650 and 630 degrees C were adopted. The temperature ranges examined had an obvious influence on the modification of the primary Mg2Si crystals. For a starting temperature of 770 degrees C, the average size of the primary Mg2Si crystals could be significantly reduced with further decrease in the ending temperature to 700 and 630 degrees C, with agglomeration of the refined primary Mg2Si crystals in these two samples was observed. For a starting temperature of 700 degrees C, the average sizes of the primary Mg2Si crystals could also be reduced, although no obvious agglomeration of the refined primary Mg2Si crystals was observed. The sample treated in the temperature range between 700 and 630 degrees C had primary Mg2Si crystals with the lowest average size and the highest uniformity of size. [doi:10.2320/matertrans.MRA2008366]
  • A. Eskandarpour, M. Tanahashi, Y. Bando, K. Iwai, M. Okido, S. Asai INTERNATIONAL JOURNAL OF MODERN PHYSICS B 22 (18-19) 3107 -3113 2008年07月 [査読無し][通常論文]
     
    A new chemical adsorbent for fluoride, phosphate and chromium removals for use in a high magnetic filtration process was produced by applying a novel nanomagnetite aggregation process through the generating procedure of an iron oxide hydroxide. The experimental work to produce the new adsorbent can be divided into two sequential steps: (1) the formation of nanomagnetite particles by means of a chemical precipitation and (2) embedding the nanomagnetite particles, in a solute state, into an iron oxyhydroxide crystal aggregates, before crystallization, to form the new adsorbent. The experimental results obtained from VSM, zeta potential, adsorption trials and SEM pictures obviously reveal a great alteration in the main properties of the new adsorbent comparing to the base iron component material. The new adsorbent not only has a much higher ions adsorption capacity but also can effectively comes to work with a magnetically assisted water treating system due to its enhanced magnetic susceptibility.
  • A. Eskandarpour, M. Tanahashi, Y. Bando, K. Iwai, M. Okido, S. Asai INTERNATIONAL JOURNAL OF MODERN PHYSICS B 22 (18-19) 3107 -3113 2008年07月 [査読無し][通常論文]
     
    A new chemical adsorbent for fluoride, phosphate and chromium removals for use in a high magnetic filtration process was produced by applying a novel nanomagnetite aggregation process through the generating procedure of an iron oxide hydroxide. The experimental work to produce the new adsorbent can be divided into two sequential steps: (1) the formation of nanomagnetite particles by means of a chemical precipitation and (2) embedding the nanomagnetite particles, in a solute state, into an iron oxyhydroxide crystal aggregates, before crystallization, to form the new adsorbent. The experimental results obtained from VSM, zeta potential, adsorption trials and SEM pictures obviously reveal a great alteration in the main properties of the new adsorbent comparing to the base iron component material. The new adsorbent not only has a much higher ions adsorption capacity but also can effectively comes to work with a magnetically assisted water treating system due to its enhanced magnetic susceptibility.
  • Kazuhiko Iwai, Akbar Eskandarpour, Manabu Usui, Kento Sugiura SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 9 (2) 5pp 2008年06月 [査読無し][通常論文]
     
    A force and/or torque are induced in a material under the imposition of a magnetic field. Their magnitudes are different from those acting on the surrounding materials because of the difference in their physical properties. Therefore, a magnetic field is a powerful tool for controlling a second phase in a mother phase such as particles suspended in a liquid. In this paper, we focus on two processes. The first one is a novel method of magnetic filtration in which schwertmannite particles in wastewater are controlled using a magnetic field. The second one is a refining process for a metallic alloy structure during solidification in which solid particles suspended in the liquid phase are controlled using the force excited by the simultaneous imposition of a magnetic field and alternating current.
  • Kazuhiko Iwai, Akbar Eskandarpour, Manabu Usui, Kento Sugiura SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 9 (2) 5pp 2008年06月 [査読無し][通常論文]
     
    A force and/or torque are induced in a material under the imposition of a magnetic field. Their magnitudes are different from those acting on the surrounding materials because of the difference in their physical properties. Therefore, a magnetic field is a powerful tool for controlling a second phase in a mother phase such as particles suspended in a liquid. In this paper, we focus on two processes. The first one is a novel method of magnetic filtration in which schwertmannite particles in wastewater are controlled using a magnetic field. The second one is a refining process for a metallic alloy structure during solidification in which solid particles suspended in the liquid phase are controlled using the force excited by the simultaneous imposition of a magnetic field and alternating current.
  • Jun Akiyama, Hidefumi Asano, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 49 (4) 787 -791 2008年04月 [査読無し][通常論文]
     
    A high magnetic field is a useful tool to control the crystal alignment of nonmagnetic materials such as metals, ceramics and polymers. However, the uniaxial alignment of hexagonal crystals with a magnetic susceptibility of chi(c) < chi(a) cannot be achieved under a static magnetic field, because the c-axis could lie along any arbitrary direction in the plane perpendicular to the direction of the magnetic field. For the uniaxial alignment of these materials, the imposition of a rotating magnetic field during a slip casting process has been proposed. In this study, both theoretical analysis and model experiment have been conducted for the elucidation of the crystal alignment phenomena under a rotating magnetic field and for the quantitative clarification of the optimum operating parameters such as magnetic field strength and viscosity of the medium surrounding the crystals. It has been found that the alignment time decreased with the magnetic field strength and/or with an increase in the viscosity of the surrounding medium. This relation is in contrary to the case of the crystal alignment under the static magnetic field. The result of the model experiment agrees well with that obtained by the theoretical analysis.
  • Takeshi Hagio, Tomohiko Tanase, Jun Akiyama, Kazuhiko Iwai, Shigeo Asai JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 116 (1349) 79 -82 2008年01月 [査読無し][通常論文]
     
    Hydroxyapatite (HAp) is a type of calcium phosphate widely applied in the biomedical field. HAp is a main inorganic component of hard tissues of vertebrates and is a bioactive ceramic which shows a high biological affinity. The crystal of HAp exhibits an anisotropic nature depending on its crystal planes which is stemmed from its anisotropic crystal structure belonging to the hexagonal system. For instance, anions and acidic proteins are mainly adsorbed onto the a-plane of HAp crystals while cations and basic proteins are adsorbed onto the c-plane. Anisotropic nature like so can be utilized by controlling the alignment of crystals consisting the material. Alignment control of HAp crystals in a particular direction is an effective way to improve the properties like absorbability, bioactivity and biological affinity on the surface of biomedical materials. On the other hand, the recent development of superconducting technology has enabled us to control the crystal alignment of not only magnetic substances but also nonmagnetic substances with magnetic anisotropy like HAp by imposing a high magnetic field. In this study, we formed crystallographically aligned HAp bulks by using a high magnetic field and evaluated the degree of the crystal alignment. In addition, we evaluated the biological affinity on the surface of the samples.
  • Akbar Eskandarpour, Maurice S. Onyang, Mitsuru Tanahashi, Aoyi Ochieng, Yoshiyuki Bando, Kazuhiko Iwai, Masazumi Okido, Shigeo Asai ISIJ INTERNATIONAL 48 (2) 240 -244 2008年 [査読無し][通常論文]
     
    The fine particles of schwertmannite as an iron oxyhydroxide adsorbent has been suggested as a novel and strong Cr(VI) sorbent for treatment of Cr-contaminated industrial wastewater. The removal process was conducted in both batch and continuous trials. As a result of the batch experiments, the maximal adsorption capacity of the schwertmannite was obtained as 178 mg/g which was quite high amount in comparison with the usual applied Cr(VI) sorbents in the literatures. The continuous removal process involved a combination of a fixed bed column with a high gradient magnetic field which was firstly introduced as a novel designation of a fixed bed column to overcome the difficulties accompanied with the application of some especial fine particle adsorbents through the fixed-beds. The experimental results revealed that the magnetization force had a great function in this process to control the shape and the fitness of the bed during the sorption test as well as to simplify the experimental set-up.
  • Manabu Usui, Shigeo Asai, Kazuhiko Iwai ISIJ INTERNATIONAL 48 (3) 330 -333 2008年 [査読無し][通常論文]
     
    The Sn-10%Pb alloy has been solidified under the imposition of a direct current and a static magnetic field perpendicular each other for the excitation of an electromagnetic force in the local region of the sample to clarify the effect of operating parameters on the solidified structure. The electromagnetic force induced by the simultaneous imposition of the direct current and the static magnetic field does not excite the nucleation in this investigation. And the solidified structures obtained under the different intensities of the direct current and the static magnetic field are compared each other for optimization of the electromagnetic field in this process. Increase in the direct current is preferable for the refined structure formation under the constant magnetic field intensity. Under the constant product of the direct current and the static magnetic field, refining effect of the solidified structure is the same level under the certain value of the magnetic field. Over this critical magnetic field, the refining effect decreases because the melt flow caused by the imposed electromagnetic force is suppressed by the interaction between the magnetic field and the fluid motion.
  • Masazumi Okido, Toshihiro Takakuwa, Akbar Eskandarpour, Ryoichi Ichino, Kazuhiko Iwai ISIJ INTERNATIONAL 48 (5) 685 -689 2008年 [査読無し][通常論文]
     
    Selective separation of phosphorous ion compounds in plating baths is of great interest. Schwertmannite, found as a strong P-sorbent in our pervious works, was used for this purpose as an inorganic chemical adsorbent, The effect of pH as a significant operating parameter on P-adsorption on schwertmannite in this process as well as on the stability of schwertmannite was thoroughly investigated. The experimental results showed that the hypophosphite H2PO2- was relatively difficult to exchange with sulfate units in schwertmannite in comparison with monoorthophpsphite H2PO3 and monoorthophosphate H2PO4. Moreover, batch kinetic trials revealed that the obtained data was fairly fitted to pseudo-second-order models.
  • Yi Yuan, Kensuke Sassa, Kazuhil Iwai, Qiang Wang, Jichen He, Shigeo Asai ISIJ INTERNATIONAL 48 (7) 901 -905 2008年 [査読無し][通常論文]
     
    Solidification experiments of Fe-0.44%Cu and Fe-3.95%C-0.40%Cu alloys were conducted to investigate the effects of an intense magnetic field on copper distribution in their solidified structures. Experiments with melting and solidifying the samples were carried out in a superconducting magnet. Around the center of the vertical cross-section of the solidified sample, multiple line analysis of copper concentration was conducted with the help of FE-SEM/EDS. The following results have been found. The copper distribution in Fe-0.44%Cu alloy is independent of the imposition of the magnetic field during the solidification. On the other hand, the solidifying process under a 10T magnetic field tends to make a uniform micro distribution of copper in Fe-3.95%C-0.40%Cu alloy in comparison with the sample solidified without the magnetic field.
  • Kazuhiko Iwai, Manalbu Usui, Shigeo Asai ISIJ INTERNATIONAL 48 (9) 1206 -1209 2008年 [査読無し][通常論文]
     
    A new crystal-alignment process in which both a static magnetic field and a direct electric current are imposed on an alloy during solidification was proposed and tested experimentally on Sn-10mass%Pb alloy. Various intensities of a static magnetic field and a direct current were imposed on the sample during solidification. After solidification, cross-sections of the samples were polished and the crystal alignment was evaluated by means of X-ray diffraction (XRD). As predicted theoretically, the peaks corresponding to the (200) and (220) planes were intensified in the XRD analysis when a static magnetic field larger of 3T or more was imposed, whereas no crystal alignment was observed with a 0.1 T magnetic field. Therefore, crystal alignment was achieved by this process, and the critical intensity for crystal alignment is between 0.1 T and 3T under the experimental conditions studied.
  • Solidified Structure Control of Metallic Alloys using Electromagnetic Oscillation
    International Journal of Cast Metals Research 21 (1-4) 152 -155 2008年 [査読無し][通常論文]
  • Takeshi Hagio, Tomohiko Tanase, Jun Akiyama, Kazuhiko Iwai, Shigeo Asai JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 116 (1349) 79 -82 2008年01月 [査読無し][通常論文]
     
    Hydroxyapatite (HAp) is a type of calcium phosphate widely applied in the biomedical field. HAp is a main inorganic component of hard tissues of vertebrates and is a bioactive ceramic which shows a high biological affinity. The crystal of HAp exhibits an anisotropic nature depending on its crystal planes which is stemmed from its anisotropic crystal structure belonging to the hexagonal system. For instance, anions and acidic proteins are mainly adsorbed onto the a-plane of HAp crystals while cations and basic proteins are adsorbed onto the c-plane. Anisotropic nature like so can be utilized by controlling the alignment of crystals consisting the material. Alignment control of HAp crystals in a particular direction is an effective way to improve the properties like absorbability, bioactivity and biological affinity on the surface of biomedical materials. On the other hand, the recent development of superconducting technology has enabled us to control the crystal alignment of not only magnetic substances but also nonmagnetic substances with magnetic anisotropy like HAp by imposing a high magnetic field. In this study, we formed crystallographically aligned HAp bulks by using a high magnetic field and evaluated the degree of the crystal alignment. In addition, we evaluated the biological affinity on the surface of the samples.
  • Akbar Eskandarpour, Maurice S. Onyang, Mitsuru Tanahashi, Aoyi Ochieng, Yoshiyuki Bando, Kazuhiko Iwai, Masazumi Okido, Shigeo Asai ISIJ INTERNATIONAL 48 (2) 240 -244 2008年 [査読無し][通常論文]
     
    The fine particles of schwertmannite as an iron oxyhydroxide adsorbent has been suggested as a novel and strong Cr(VI) sorbent for treatment of Cr-contaminated industrial wastewater. The removal process was conducted in both batch and continuous trials. As a result of the batch experiments, the maximal adsorption capacity of the schwertmannite was obtained as 178 mg/g which was quite high amount in comparison with the usual applied Cr(VI) sorbents in the literatures. The continuous removal process involved a combination of a fixed bed column with a high gradient magnetic field which was firstly introduced as a novel designation of a fixed bed column to overcome the difficulties accompanied with the application of some especial fine particle adsorbents through the fixed-beds. The experimental results revealed that the magnetization force had a great function in this process to control the shape and the fitness of the bed during the sorption test as well as to simplify the experimental set-up.
  • Manabu Usui, Shigeo Asai, Kazuhiko Iwai ISIJ INTERNATIONAL 48 (3) 330 -333 2008年 [査読無し][通常論文]
     
    The Sn-10%Pb alloy has been solidified under the imposition of a direct current and a static magnetic field perpendicular each other for the excitation of an electromagnetic force in the local region of the sample to clarify the effect of operating parameters on the solidified structure. The electromagnetic force induced by the simultaneous imposition of the direct current and the static magnetic field does not excite the nucleation in this investigation. And the solidified structures obtained under the different intensities of the direct current and the static magnetic field are compared each other for optimization of the electromagnetic field in this process. Increase in the direct current is preferable for the refined structure formation under the constant magnetic field intensity. Under the constant product of the direct current and the static magnetic field, refining effect of the solidified structure is the same level under the certain value of the magnetic field. Over this critical magnetic field, the refining effect decreases because the melt flow caused by the imposed electromagnetic force is suppressed by the interaction between the magnetic field and the fluid motion.
  • Masazumi Okido, Toshihiro Takakuwa, Akbar Eskandarpour, Ryoichi Ichino, Kazuhiko Iwai ISIJ INTERNATIONAL 48 (5) 685 -689 2008年 [査読無し][通常論文]
     
    Selective separation of phosphorous ion compounds in plating baths is of great interest. Schwertmannite, found as a strong P-sorbent in our pervious works, was used for this purpose as an inorganic chemical adsorbent, The effect of pH as a significant operating parameter on P-adsorption on schwertmannite in this process as well as on the stability of schwertmannite was thoroughly investigated. The experimental results showed that the hypophosphite H2PO2- was relatively difficult to exchange with sulfate units in schwertmannite in comparison with monoorthophpsphite H2PO3 and monoorthophosphate H2PO4. Moreover, batch kinetic trials revealed that the obtained data was fairly fitted to pseudo-second-order models.
  • Yi Yuan, Kensuke Sassa, Kazuhil Iwai, Qiang Wang, Jichen He, Shigeo Asai ISIJ INTERNATIONAL 48 (7) 901 -905 2008年 [査読無し][通常論文]
     
    Solidification experiments of Fe-0.44%Cu and Fe-3.95%C-0.40%Cu alloys were conducted to investigate the effects of an intense magnetic field on copper distribution in their solidified structures. Experiments with melting and solidifying the samples were carried out in a superconducting magnet. Around the center of the vertical cross-section of the solidified sample, multiple line analysis of copper concentration was conducted with the help of FE-SEM/EDS. The following results have been found. The copper distribution in Fe-0.44%Cu alloy is independent of the imposition of the magnetic field during the solidification. On the other hand, the solidifying process under a 10T magnetic field tends to make a uniform micro distribution of copper in Fe-3.95%C-0.40%Cu alloy in comparison with the sample solidified without the magnetic field.
  • Kazuhiko Iwai, Manalbu Usui, Shigeo Asai ISIJ INTERNATIONAL 48 (9) 1206 -1209 2008年 [査読無し][通常論文]
     
    A new crystal-alignment process in which both a static magnetic field and a direct electric current are imposed on an alloy during solidification was proposed and tested experimentally on Sn-10mass%Pb alloy. Various intensities of a static magnetic field and a direct current were imposed on the sample during solidification. After solidification, cross-sections of the samples were polished and the crystal alignment was evaluated by means of X-ray diffraction (XRD). As predicted theoretically, the peaks corresponding to the (200) and (220) planes were intensified in the XRD analysis when a static magnetic field larger of 3T or more was imposed, whereas no crystal alignment was observed with a 0.1 T magnetic field. Therefore, crystal alignment was achieved by this process, and the critical intensity for crystal alignment is between 0.1 T and 3T under the experimental conditions studied.
  • Solidified Structure Control of Metallic Alloys using Electromagnetic Oscillation
    International Journal of Cast Metals Research 21 (1-4) 152 -155 2008年 [査読無し][通常論文]
  • Tomohiko Tanase, Jun Akiyama, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 48 (11) 2855 -2860 2007年11月 [査読無し][通常論文]
     
    Hydroxyapatite (HAp) is the main mineral component of bone and is used as a raw material for artificial bones and teeth, and as an adsorbent in liquid chromatography, among its other uses. As a result of its anisotropic crystal structure, HAp shows adsorption behavior that depends on the crystal plane. However, the differences between the a-plane and the c-plane of the HAp crystal in terms of their bioactivity, cell-propagation behavior, etc., have not yet been fully clarified. In this study, we fabricated highly crystallographically aligned samples of HAp by using a 10-T magnetic field, and we studied the effects of the specific crystal plane of HAp on its bioactivity by immersing the samples in a simulated body fluid. HAp is precipitated on both a-plane- and c-plane-aligned HAp sample surfaces. The rate of precipitation on a HAp sample immersed in the simulated body fluid depended on the crystal plane, especially during the first 24 h of immersion. Because the rate of precipitation on the c-plane is faster than on the a-plane, HAp is precipitated preferentially on the c-plane during the early stages, of precipitation.
  • Takenori Kohama, Hiroki Takeuchi, Manabu Usui, Jun Akiyama, Mun-Gyu Sung, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 48 (11) 2867 -2871 2007年11月 [査読無し][通常論文]
     
    The crystal alignment behavior of bismuth particles in the presence of an imposed static magnetic field was examined in situ by X-ray diffraction. Because the c-plane of a bismuth crystal is aligned perpendicular to the direction of a magnetic field, the temporal variation in the (110) peak intensity of bismuth was measured by X-ray diffraction to determine the crystal alignment. The alignment time decreased as the magnetic field strength increased. This tendency is similar to that calculated for the relaxation time. The difference in the magnetic susceptibility between the magnetically easy and hard axes is the driving force for the crystal alignment, and aggregation of the bismuth particles decreases this driving force. The effective difference in magnetic susceptibility for aggregated bismuth particles was estimated by measuring the alignment time of the particles under magnetic fields of various strengths. The estimated effective difference in magnetic susceptibility generally increases with a decreasing magnetic field strength. Furthermore, the interference to crystal rotation caused by the interaction between the induced current and the imposed magnetic field is negligible in this study. To decrease the strength of the magnetic field required for alignment of crystals, the number of small particles should be reduced.
  • Yasuhiko Sakaida, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 48 (11) 2872 -2876 2007年11月 [査読無し][通常論文]
     
    It is well known that the transport of atoms, ions and holes in a material is induced by electromigration. This implies that electromigaration can control the structure of a material. In this study, an electric current was applied to a titanium sample that was subjected to a static magnetic field to investigate the effects of the electric current and the static magnetic field on crystal alignment in titanium. An intensity ratio of (002) peak to (100) peak in XRD analysis was introduced as a crystal alignment index. Because the magnetic susceptibility of titanium in the c-axis is larger than what it is in the a-axis, titanium crystals having a c-axis parallel to the magnetic field are stable from the viewpoint of magnetization energy. However, the numbers of these crystals decreased after the experiment. On the other hand, the c-axis of the titanium crystals aligned themselves itself to become perpendicular to the direction of flow of the electric current to reduce the Joule loss in the sample, because the specific resistance in the c-axis was larger than that in the a-axis. This agrees with the experimental result. Therefore, in this experiment the titanium crystals in the sample aligned themselves to reduce the Joule loss even though the magnetic energy was larger than the thermal fluctuation in this experiment.
  • Akbar Eskandarpour, Maurice S. Onyango, Yoshiyuki Bando, Masazumi Okido, Kazuhiko Iwai CHEMISTRY LETTERS 36 (11) 1392 -1393 2007年11月 [査読無し][通常論文]
     
    A new magnetically assisted wastewater treating system has been suggested for Cr-VI-contaminated waters using a novel and strong Cr-sorbent, namely, schwertmannite. The system contains a fixed-bed column, put in a high magnetic field, which was alternately packed with schwertmannite fine particles and iron wools as a ferromagnetic porous media. The obtained results confirm its high efficiency.
  • Tomohiko Tanase, Jun Akiyama, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 48 (11) 2855 -2860 2007年11月 [査読無し][通常論文]
     
    Hydroxyapatite (HAp) is the main mineral component of bone and is used as a raw material for artificial bones and teeth, and as an adsorbent in liquid chromatography, among its other uses. As a result of its anisotropic crystal structure, HAp shows adsorption behavior that depends on the crystal plane. However, the differences between the a-plane and the c-plane of the HAp crystal in terms of their bioactivity, cell-propagation behavior, etc., have not yet been fully clarified. In this study, we fabricated highly crystallographically aligned samples of HAp by using a 10-T magnetic field, and we studied the effects of the specific crystal plane of HAp on its bioactivity by immersing the samples in a simulated body fluid. HAp is precipitated on both a-plane- and c-plane-aligned HAp sample surfaces. The rate of precipitation on a HAp sample immersed in the simulated body fluid depended on the crystal plane, especially during the first 24 h of immersion. Because the rate of precipitation on the c-plane is faster than on the a-plane, HAp is precipitated preferentially on the c-plane during the early stages, of precipitation.
  • Takenori Kohama, Hiroki Takeuchi, Manabu Usui, Jun Akiyama, Mun-Gyu Sung, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 48 (11) 2867 -2871 2007年11月 [査読無し][通常論文]
     
    The crystal alignment behavior of bismuth particles in the presence of an imposed static magnetic field was examined in situ by X-ray diffraction. Because the c-plane of a bismuth crystal is aligned perpendicular to the direction of a magnetic field, the temporal variation in the (110) peak intensity of bismuth was measured by X-ray diffraction to determine the crystal alignment. The alignment time decreased as the magnetic field strength increased. This tendency is similar to that calculated for the relaxation time. The difference in the magnetic susceptibility between the magnetically easy and hard axes is the driving force for the crystal alignment, and aggregation of the bismuth particles decreases this driving force. The effective difference in magnetic susceptibility for aggregated bismuth particles was estimated by measuring the alignment time of the particles under magnetic fields of various strengths. The estimated effective difference in magnetic susceptibility generally increases with a decreasing magnetic field strength. Furthermore, the interference to crystal rotation caused by the interaction between the induced current and the imposed magnetic field is negligible in this study. To decrease the strength of the magnetic field required for alignment of crystals, the number of small particles should be reduced.
  • Yasuhiko Sakaida, Kazuhiko Iwai, Shigeo Asai MATERIALS TRANSACTIONS 48 (11) 2872 -2876 2007年11月 [査読無し][通常論文]
     
    It is well known that the transport of atoms, ions and holes in a material is induced by electromigration. This implies that electromigaration can control the structure of a material. In this study, an electric current was applied to a titanium sample that was subjected to a static magnetic field to investigate the effects of the electric current and the static magnetic field on crystal alignment in titanium. An intensity ratio of (002) peak to (100) peak in XRD analysis was introduced as a crystal alignment index. Because the magnetic susceptibility of titanium in the c-axis is larger than what it is in the a-axis, titanium crystals having a c-axis parallel to the magnetic field are stable from the viewpoint of magnetization energy. However, the numbers of these crystals decreased after the experiment. On the other hand, the c-axis of the titanium crystals aligned themselves itself to become perpendicular to the direction of flow of the electric current to reduce the Joule loss in the sample, because the specific resistance in the c-axis was larger than that in the a-axis. This agrees with the experimental result. Therefore, in this experiment the titanium crystals in the sample aligned themselves to reduce the Joule loss even though the magnetic energy was larger than the thermal fluctuation in this experiment.
  • Akbar Eskandarpour, Maurice S. Onyango, Yoshiyuki Bando, Masazumi Okido, Kazuhiko Iwai CHEMISTRY LETTERS 36 (11) 1392 -1393 2007年11月 [査読無し][通常論文]
     
    A new magnetically assisted wastewater treating system has been suggested for Cr-VI-contaminated waters using a novel and strong Cr-sorbent, namely, schwertmannite. The system contains a fixed-bed column, put in a high magnetic field, which was alternately packed with schwertmannite fine particles and iron wools as a ferromagnetic porous media. The obtained results confirm its high efficiency.
  • Cunyou Wu, Kensuke Sassa, Kazuhiko Iwai, Shigeo Asai MATERIALS LETTERS 61 (7) 1567 -1571 2007年03月 [査読無し][通常論文]
     
    A unidirectionally oriented hydroxyapatite (HAp)/collagen composite was prepared by using a high magnetic field. In the present study, a calcium-containing collagen solution was mixed with a phosphate-containing solution and kept at a temperature of 37 degrees C. During this process, the heat-induced self-assembling of collagen molecules and precipitation of HAp crystals took place simultaneously. Both collagen fibrils and HAp crystals have magnetic susceptibility anisotropy, which makes it possible for them to be oriented by using a high magnetic field. In order to prepare a unidirectionally oriented structure, samples were rotated when the high magnetic field was imposed perpendicularly to the rotation axis. The results indicated that collagen fibrils have been unidirectionally oriented with weakly crystallized HAp nanocrystals closely attached along the surfaces of the collagen fibrils. A biocomposite with similar structural and composition to natural bones has been prepared. (c) 2006 Elsevier B.V. All rights reserved.
  • Cunyou Wu, Kensuke Sassa, Kazuhiko Iwai, Shigeo Asai MATERIALS LETTERS 61 (7) 1567 -1571 2007年03月 [査読無し][通常論文]
     
    A unidirectionally oriented hydroxyapatite (HAp)/collagen composite was prepared by using a high magnetic field. In the present study, a calcium-containing collagen solution was mixed with a phosphate-containing solution and kept at a temperature of 37 degrees C. During this process, the heat-induced self-assembling of collagen molecules and precipitation of HAp crystals took place simultaneously. Both collagen fibrils and HAp crystals have magnetic susceptibility anisotropy, which makes it possible for them to be oriented by using a high magnetic field. In order to prepare a unidirectionally oriented structure, samples were rotated when the high magnetic field was imposed perpendicularly to the rotation axis. The results indicated that collagen fibrils have been unidirectionally oriented with weakly crystallized HAp nanocrystals closely attached along the surfaces of the collagen fibrils. A biocomposite with similar structural and composition to natural bones has been prepared. (c) 2006 Elsevier B.V. All rights reserved.
  • Yosuke Yamamoto, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 47 (7) 960 -964 2007年 [査読無し][通常論文]
     
    Thermal plasma has advantages such as clean energy, good controllability, high power density and so on. Therefore, it has been applied to the steel industry such as heat source of molten steel in a tundish and secondary refining. For these processes, precise control of the plasma is requested for high efficiency and for high-quality products. Because the plasma is electrically conductive fluid, a magnetic field is one of the powerful tools to control its behavior under non-contact operation. Therefore, investigations to control the plasma using the magnetic field have been done. In this investigation, a DC transferred plasma arc behavior has been investigated under imposition of an alternating magnetic field of frequency range between 5 Hz and 2 000 Hz in which the magnetic field direction is perpendicular or parallel to the plasma arc current. The forces governing the plasma behavior is estimated by the simple calculation of forces acting the plasma, Under the imposition of the perpendicular magnetic field to the plasma arc current, a plasma oscillation width is constant when the magnetic field frequency is less than 50 Hz, while it decreases with increase in the magnetic field frequency if the frequency is larger than the 50 Hz. Under the imposition of the parallel magnetic field of 1 000 Hz to the plasma arc current, a burned area on a copper block by the plasma is smaller than that without the magnetic field while the burned area with the low frequency magnetic field less than 1 000 Hz is larger than that without the magnetic field.
  • Hideyuki Yasuda, Takehiko Toh, Kazuhiko Iwai, Kazuki Morita ISIJ INTERNATIONAL 47 (4) 619 -626 2007年 [査読無し][通常論文]
     
    This paper reviews recent trends of electromagnetic processing in steelmaking, casting and solidification processing. Electromagnetic vibration for controlling the solidified structure and application of microwave in materials processing are also presented. Aim of this paper is to prospect the recent trends in electromagnetic processing of materials.
  • Akbar Eskandarpour, Kensuke Sassa, Yoshiyuki Bando, Masazumi Okido, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 47 (4) 563 -567 2007年 [査読無し][通常論文]
     
    Phosphate removal from wastewater using fine-particles of schwertmannite was performed by use of a semi-continuous magnetic filtration. The effects of two main parameters of magnetization and drag forces on the performance of the magnetic filtration were investigated. By increasing the magnetic intensity from 0.4 to 4T, the magnetic filter performance was increased from less than 0.7 up to 0.99 depending on the fluid velocity through the magnetic filter. The measured results in magnetic filtration tests were in consistence with the theoretical results applied in this study. It was revealed that the schwertmannite possessed a high regeneration ability with trivial loss of adsorption capacity. Moreover, the phosphate adsorption capacity in schwertmannite was remarkably increased by using an acid-modification method.
  • Takuya Ono, Kensuke Sassa, Kazuhiko Iwai, Hideyuki Ohtsuka, Shigeo Asai ISIJ INTERNATIONAL 47 (4) 608 -611 2007年 [査読無し][通常論文]
     
    A new method that provides quantitative information of phase transformation in solid metals by measuring a magnetic susceptibility has been proposed. The principle of the method is based on that the magnetic susceptibility is different from one phase to another and additive identity holds in the magnetic susceptibilities. This method directly reflects the phase transformation and provides more accurate information in comparison with conventional methods, which are based on indirect measurements of various physical properties or micro-structure observation. This method not only enables continuous measurement of phase trans-formation, but also can clearly indicate the start and end points of it. In this study, this new method was applied to measure the alpha/gamma isothermal transformation rate in an Fe-C alloy above the Curie temperature.
  • Akbar Eskandarpour, Kensuke Sassa, Yoshiyuki Bando, Hiroshi Ikuta, Kazuhiko Iwai, Masazumi Okido, Shigeo Asai ISIJ INTERNATIONAL 47 (4) 558 -562 2007年 [査読無し][通常論文]
     
    A new chemical adsorbent for fluoride and phosphate removals was produced by applying a novel nano-magnetite aggregation process through the formation procedure of an iron oxide hydroxide, i.e., schwertmannite. Although there was no evidence of magnetite related peaks in the XRD Pattern of the new adsorbent, because of the very small amount of the used magnetite particles, the SEM picture reveals a surface alteration on the crystal structure of the new adsorbent comparing to the schwertmannite. The results of magnetic removal of fluoride and phosphate using the new adsorbent indicate that nanomagnetite aggregation process not only improves the magnetic property, but also provides a highly-promoted fluoride and phosphate adsorption capacities comparing to the schwertmannite.
  • 秋山 順, 浅野 秀文, 岩井 一彦, 浅井 滋生 日本金属学会誌 71 (1) 108 -112 2007年 [査読無し][通常論文]
  • 臼井 学, 岩井 一彦, 浅井 滋生 鉄と鋼 93 (6) 434 -437 2007年 [査読無し][通常論文]
  • 秋山 順, 橋本 雅美, 高玉 博朗, 永田 夫久江, 横川 善之, 佐々 健介, 岩井 一彦, 浅井 滋生 日本金属学会誌 71 (4) 427 -431 2007年 [査読無し][通常論文]
  • Alignment of HAp crystal using a Sample Rotation in a Static Magnetic Field
    Materials Science Forum 539-543 716 -719 2007年 [査読無し][通常論文]
  • Manabu Usui, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 47 (11) 1571 -1574 2007年 [査読無し][通常論文]
     
    Experimental work has been done to investigate difference of structures solidified under the imposition of an oscillating electromagnetic force and that under the imposition of a DC electromagnetic force. For excitation of the oscillating electromagnetic force, a static magnetic field and an alternating current are simultaneously imposed on a Sn-10 mass% Pb alloy while the static magnetic field and a direct current are simultaneously imposed on the alloy for the excitation of the DC electromagnetic force. After the solidification, macrostructure is observed and it is concluded that both the electromagnetic forces have refining function of the solidified structure. Though magnitude of the DC force is weaker than that of the oscillating force, grain size solidified under the imposition of the DC force is smaller than that solidified under the imposition of the oscillating force. Nucleation is not induced under the imposition of the DC force while it is induced when the oscillating force is imposed on the alloy.
  • Manabu Usui, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 47 (11) 1613 -1617 2007年 [査読無し][通常論文]
     
    For optimization of alternating current imposing period in the crystal alignment process in which both a static magnetic field and an alternating current are imposed on an alloy during solidification, experimental work has been done using a Sn-10mass%Pb alloy. Index of crystal alignment decreases with increase in the imposing period of the alternating current because the electromagnetic torque induced in the sample disturbs the alignment of solid particles suspended in the liquid phase. Electromagnetic torque is dominant as resistance of the crystal rotation to magnetically preferred direction when the size of the crystal is 21 Pm or larger. For the optimization of the crystal alignment in this process, imposing period of the electric current and the magnetic field should be controlled as follows. The electric current and the magnetic field are simultaneously imposed on the alloy only in the initial stage of the solidification. Then the electric current is turned off and only the magnetic field is imposed during the solidification.
  • LIQUID METAL FREE SURFACE MOTION SUBMERGED IN AN AC MAGNETIC FIELD
    Materials Science Forum 561-565 1071 -1074 2007年 [査読無し][通常論文]
  • ALIGNMENT OF PRIMARY PHASE OF A BINARY ALLOY DURING SOLIDIFICATION
    Advanced Materials Research 26-28 563 -565 2007年 [査読無し][通常論文]
  • STRUCTURE CONTROL OF HYDROXYAPATITE USING A MAGNETIC FIELD
    Materials Science Forum 561-565 1565 -1568 2007年 [査読無し][通常論文]
  • Yosuke Yamamoto, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 47 (7) 960 -964 2007年 [査読無し][通常論文]
     
    Thermal plasma has advantages such as clean energy, good controllability, high power density and so on. Therefore, it has been applied to the steel industry such as heat source of molten steel in a tundish and secondary refining. For these processes, precise control of the plasma is requested for high efficiency and for high-quality products. Because the plasma is electrically conductive fluid, a magnetic field is one of the powerful tools to control its behavior under non-contact operation. Therefore, investigations to control the plasma using the magnetic field have been done. In this investigation, a DC transferred plasma arc behavior has been investigated under imposition of an alternating magnetic field of frequency range between 5 Hz and 2 000 Hz in which the magnetic field direction is perpendicular or parallel to the plasma arc current. The forces governing the plasma behavior is estimated by the simple calculation of forces acting the plasma, Under the imposition of the perpendicular magnetic field to the plasma arc current, a plasma oscillation width is constant when the magnetic field frequency is less than 50 Hz, while it decreases with increase in the magnetic field frequency if the frequency is larger than the 50 Hz. Under the imposition of the parallel magnetic field of 1 000 Hz to the plasma arc current, a burned area on a copper block by the plasma is smaller than that without the magnetic field while the burned area with the low frequency magnetic field less than 1 000 Hz is larger than that without the magnetic field.
  • Hideyuki Yasuda, Takehiko Toh, Kazuhiko Iwai, Kazuki Morita ISIJ INTERNATIONAL 47 (4) 619 -626 2007年 [査読無し][通常論文]
     
    This paper reviews recent trends of electromagnetic processing in steelmaking, casting and solidification processing. Electromagnetic vibration for controlling the solidified structure and application of microwave in materials processing are also presented. Aim of this paper is to prospect the recent trends in electromagnetic processing of materials.
  • Akbar Eskandarpour, Kensuke Sassa, Yoshiyuki Bando, Masazumi Okido, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 47 (4) 563 -567 2007年 [査読無し][通常論文]
     
    Phosphate removal from wastewater using fine-particles of schwertmannite was performed by use of a semi-continuous magnetic filtration. The effects of two main parameters of magnetization and drag forces on the performance of the magnetic filtration were investigated. By increasing the magnetic intensity from 0.4 to 4T, the magnetic filter performance was increased from less than 0.7 up to 0.99 depending on the fluid velocity through the magnetic filter. The measured results in magnetic filtration tests were in consistence with the theoretical results applied in this study. It was revealed that the schwertmannite possessed a high regeneration ability with trivial loss of adsorption capacity. Moreover, the phosphate adsorption capacity in schwertmannite was remarkably increased by using an acid-modification method.
  • Takuya Ono, Kensuke Sassa, Kazuhiko Iwai, Hideyuki Ohtsuka, Shigeo Asai ISIJ INTERNATIONAL 47 (4) 608 -611 2007年 [査読無し][通常論文]
     
    A new method that provides quantitative information of phase transformation in solid metals by measuring a magnetic susceptibility has been proposed. The principle of the method is based on that the magnetic susceptibility is different from one phase to another and additive identity holds in the magnetic susceptibilities. This method directly reflects the phase transformation and provides more accurate information in comparison with conventional methods, which are based on indirect measurements of various physical properties or micro-structure observation. This method not only enables continuous measurement of phase trans-formation, but also can clearly indicate the start and end points of it. In this study, this new method was applied to measure the alpha/gamma isothermal transformation rate in an Fe-C alloy above the Curie temperature.
  • Akbar Eskandarpour, Kensuke Sassa, Yoshiyuki Bando, Hiroshi Ikuta, Kazuhiko Iwai, Masazumi Okido, Shigeo Asai ISIJ INTERNATIONAL 47 (4) 558 -562 2007年 [査読無し][通常論文]
     
    A new chemical adsorbent for fluoride and phosphate removals was produced by applying a novel nano-magnetite aggregation process through the formation procedure of an iron oxide hydroxide, i.e., schwertmannite. Although there was no evidence of magnetite related peaks in the XRD Pattern of the new adsorbent, because of the very small amount of the used magnetite particles, the SEM picture reveals a surface alteration on the crystal structure of the new adsorbent comparing to the schwertmannite. The results of magnetic removal of fluoride and phosphate using the new adsorbent indicate that nanomagnetite aggregation process not only improves the magnetic property, but also provides a highly-promoted fluoride and phosphate adsorption capacities comparing to the schwertmannite.
  • Alignment of HAp crystal using a Sample Rotation in a Static Magnetic Field
    Materials Science Forum 539-543 716 -719 2007年 [査読無し][通常論文]
  • Manabu Usui, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 47 (11) 1571 -1574 2007年 [査読無し][通常論文]
     
    Experimental work has been done to investigate difference of structures solidified under the imposition of an oscillating electromagnetic force and that under the imposition of a DC electromagnetic force. For excitation of the oscillating electromagnetic force, a static magnetic field and an alternating current are simultaneously imposed on a Sn-10 mass% Pb alloy while the static magnetic field and a direct current are simultaneously imposed on the alloy for the excitation of the DC electromagnetic force. After the solidification, macrostructure is observed and it is concluded that both the electromagnetic forces have refining function of the solidified structure. Though magnitude of the DC force is weaker than that of the oscillating force, grain size solidified under the imposition of the DC force is smaller than that solidified under the imposition of the oscillating force. Nucleation is not induced under the imposition of the DC force while it is induced when the oscillating force is imposed on the alloy.
  • Manabu Usui, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 47 (11) 1613 -1617 2007年 [査読無し][通常論文]
     
    For optimization of alternating current imposing period in the crystal alignment process in which both a static magnetic field and an alternating current are imposed on an alloy during solidification, experimental work has been done using a Sn-10mass%Pb alloy. Index of crystal alignment decreases with increase in the imposing period of the alternating current because the electromagnetic torque induced in the sample disturbs the alignment of solid particles suspended in the liquid phase. Electromagnetic torque is dominant as resistance of the crystal rotation to magnetically preferred direction when the size of the crystal is 21 Pm or larger. For the optimization of the crystal alignment in this process, imposing period of the electric current and the magnetic field should be controlled as follows. The electric current and the magnetic field are simultaneously imposed on the alloy only in the initial stage of the solidification. Then the electric current is turned off and only the magnetic field is imposed during the solidification.
  • LIQUID METAL FREE SURFACE MOTION SUBMERGED IN AN AC MAGNETIC FIELD
    Materials Science Forum 561-565 1071 -1074 2007年 [査読無し][通常論文]
  • ALIGNMENT OF PRIMARY PHASE OF A BINARY ALLOY DURING SOLIDIFICATION
    Advanced Materials Research 26-28 563 -565 2007年 [査読無し][通常論文]
  • STRUCTURE CONTROL OF HYDROXYAPATITE USING A MAGNETIC FIELD
    Materials Science Forum 561-565 1565 -1568 2007年 [査読無し][通常論文]
  • Kazuhiko Iwai, Jun Akiyama, Mun Gyu Sung, Ippei Furuhashi, Shigeo Asai SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 7 (4) 365 -368 2006年05月 [査読無し][通常論文]
     
    A magnetic field has a lot of useful functions. We focus on two of these functions. The first one is alignment of crystals with magnetic anisotropy. We aligned hydroxyapatite crystals and graphite whiskers during slip casting process under the imposition of the high magnetic field. In the case of the hydroxyapatite crystals, the sample was rotated in the magnetic field. The second function we focus on is Lorentz force induced by an electrically conductive material motion submerged in the magnetic field. We experimentally simulated bubble motion in a liquid metal by using argon bubble in a sodium chloride solution. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.
  • Kazuhiko Iwai, Jun Akiyama, Mun Gyu Sung, Ippei Furuhashi, Shigeo Asai SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 7 (4) 365 -368 2006年05月 [査読無し][通常論文]
     
    A magnetic field has a lot of useful functions. We focus on two of these functions. The first one is alignment of crystals with magnetic anisotropy. We aligned hydroxyapatite crystals and graphite whiskers during slip casting process under the imposition of the high magnetic field. In the case of the hydroxyapatite crystals, the sample was rotated in the magnetic field. The second function we focus on is Lorentz force induced by an electrically conductive material motion submerged in the magnetic field. We experimentally simulated bubble motion in a liquid metal by using argon bubble in a sodium chloride solution. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.
  • Manabu Usui, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 46 (6) 859 -863 2006年 [査読無し][通常論文]
     
    In this study, a new process for a crystal alignment of an alloy during solidification has been proposed in which the imposing periods of a static magnetic field and an alternating current are controlled. In the initial stage of the solidification both the magnetic and electric fields are imposed on the alloy to break dendrites into pieces and to spread them to the whole area of the sample. In the next stage, only the static magnetic field was applied for the sample. The function of the static magnetic field in this stage is not only the rotation of the crystals to magnetically stable direction but also the suppression of the disturbance such as liquid motion. The principle of this process was experimentally confirmed by using a Sn-10mass%Pb alloy. In the X-ray diffraction pattern of the sample solidified without the static magnetic field, the first and second highest peaks were (101)-plane and (200)-plane. That is, the crystal direction is random. On the other hand, only the peaks corresponding to a,b-plane were observed in the sample solidified under the imposition of the controlled electromagnetic field. Therefore, this process is useful for the crystal alignment of alloy.
  • 秋山 順, 橋本 雅美, 高玉 博朗, 永田 夫久江, 横川 善之, 岩井 一彦, 佐々 健介, 浅井 滋生 日本金属学会誌 70 (5) 412 -414 2006年 [査読無し][通常論文]
  • Formation of c-axis Aligned Hydroxyapatite Sheet by Simultaneous Imposition of High Magnetic Field and Mold Rotation during Slip Casting Process
    Key Engineering Materials 309-311 53 -56 2006年 [査読無し][通常論文]
  • Structure of Sn-Pb Alloy Solidified under the Simultaneous Imposition of Static Magnetic Field and Alternating Current
    Magnetohydrodynamics 42 (2-3) 335 -338 2006年 [査読無し][通常論文]
  • Manabu Usui, Kazuhiko Iwai, Shigeo Asai ISIJ INTERNATIONAL 46 (6) 859 -863 2006年 [査読無し][通常論文]
     
    In this study, a new process for a crystal alignment of an alloy during solidification has been proposed in which the imposing periods of a static magnetic field and an alternating current are controlled. In the initial stage of the solidification both the magnetic and electric fields are imposed on the alloy to break dendrites into pieces and to spread them to the whole area of the sample. In the next stage, only the static magnetic field was applied for the sample. The function of the static magnetic field in this stage is not only the rotation of the crystals to magnetically stable direction but also the suppression of the disturbance such as liquid motion. The principle of this process was experimentally confirmed by using a Sn-10mass%Pb alloy. In the X-ray diffraction pattern of the sample solidified without the static magnetic field, the first and second highest peaks were (101)-plane and (200)-plane. That is, the crystal direction is random. On the other hand, only the peaks corresponding to a,b-plane were observed in the sample solidified under the imposition of the controlled electromagnetic field. Therefore, this process is useful for the crystal alignment of alloy.
  • Formation of c-axis Aligned Hydroxyapatite Sheet by Simultaneous Imposition of High Magnetic Field and Mold Rotation during Slip Casting Process
    Key Engineering Materials 309-311 53 -56 2006年 [査読無し][通常論文]
  • Structure of Sn-Pb Alloy Solidified under the Simultaneous Imposition of Static Magnetic Field and Alternating Current
    Magnetohydrodynamics 42 (2-3) 335 -338 2006年 [査読無し][通常論文]
  • J Akiyama, M Hashimoto, H Takadama, F Nagata, Y Yokogawa, K Sassa, K Iwai, S Asai MATERIALS TRANSACTIONS 46 (11) 2514 -2517 2005年11月 [査読無し][通常論文]
     
    Orientation of hydroxyapatite (HAp) crystals is one of the promising ways to utilize their anisotropic nature of chemical and biological properties. On the other hand, the development of super conducting magnet technology enables to introduce a high magnetic field which can control crystal orientation of non-magnetic materials with magnetic anisotropy. In this study, a horizontal 10 T static magnetic field was imposed on slurry containing HAp crystals under the horizontal mold rotation during slip casting process so as to introduce c-axis orientation for some amount of crystals in the sample, and then it was sintered in atmosphere without the magnetic field. From SEM observation and X-ray diffraction, it has been found that the c-axis of pillar shape HAp crystals in the sample treated with the magnetic field and the mold rotation were oriented to a particular direction and it was enhanced by the subsequent sintering process, while the c-axis crystal orientation of the sample treated without the magnetic field and with the mold rotation was not observed before and after the sintering.
  • J Akiyama, M Hashimoto, H Takadama, F Nagata, Y Yokogawa, K Sassa, K Iwai, S Asai MATERIALS TRANSACTIONS 46 (11) 2514 -2517 2005年11月 [査読無し][通常論文]
     
    Orientation of hydroxyapatite (HAp) crystals is one of the promising ways to utilize their anisotropic nature of chemical and biological properties. On the other hand, the development of super conducting magnet technology enables to introduce a high magnetic field which can control crystal orientation of non-magnetic materials with magnetic anisotropy. In this study, a horizontal 10 T static magnetic field was imposed on slurry containing HAp crystals under the horizontal mold rotation during slip casting process so as to introduce c-axis orientation for some amount of crystals in the sample, and then it was sintered in atmosphere without the magnetic field. From SEM observation and X-ray diffraction, it has been found that the c-axis of pillar shape HAp crystals in the sample treated with the magnetic field and the mold rotation were oriented to a particular direction and it was enhanced by the subsequent sintering process, while the c-axis crystal orientation of the sample treated without the magnetic field and with the mold rotation was not observed before and after the sintering.
  • J Akiyama, M Hashimoto, H Takadama, F Nagata, Y Yokogawa, K Sassa, K Iwai, S Asai MATERIALS TRANSACTIONS 46 (2) 203 -206 2005年02月 [査読無し][通常論文]
     
    It is possible to control the crystal alignment of non-magnetic materials such as anisotropic ceramics and polymeric materials using a high magnetic field. However, the alignment of the c-axis direction in hexagonal crystals, with a magnetic susceptibility of chi(c) < chi(a,b), is uncontrollable using a static magnetic field, because the c-axis can rotate in the plane perpendicular to the direction of the magnetic field. In this study. a high magnetic field and mechanical rotation are simultaneously imposed on a sample in order to align crystals parallel to that axis (c-axis) which has small magnetic susceptibility. This process of alignment was applied to hydroxyapatite (HAp) crystals and a sample was obtained, in which the c-axis of the HAp crystals aligned in a particular direction.
  • J Akiyama, M Hashimoto, H Takadama, F Nagata, Y Yokogawa, K Sassa, K Iwai, S Asai MATERIALS TRANSACTIONS 46 (2) 203 -206 2005年02月 [査読無し][通常論文]
     
    It is possible to control the crystal alignment of non-magnetic materials such as anisotropic ceramics and polymeric materials using a high magnetic field. However, the alignment of the c-axis direction in hexagonal crystals, with a magnetic susceptibility of chi(c) < chi(a,b), is uncontrollable using a static magnetic field, because the c-axis can rotate in the plane perpendicular to the direction of the magnetic field. In this study. a high magnetic field and mechanical rotation are simultaneously imposed on a sample in order to align crystals parallel to that axis (c-axis) which has small magnetic susceptibility. This process of alignment was applied to hydroxyapatite (HAp) crystals and a sample was obtained, in which the c-axis of the HAp crystals aligned in a particular direction.
  • K Sugiura, K Iwai ISIJ INTERNATIONAL 45 (7) 962 -966 2005年 [査読無し][通常論文]
     
    Refining mechanism of solidified structure in which a static magnetic field and an alternating electrical current are simultaneously imposed on the local area of a metal or an alloy, has been experimentally examined using a Sn-10mass%Pb alloy. The refining period of the structure was examined by changing the imposing period of the electromagnetic vibration on the sample and it was confirmed that the refining period was the initial stage of solidification. The refining region was specified to be around the electrodes by inserting a stainless steel wire net in the sample while it was independent of the inserting position of the electrodes. Convection was induced by the electromagnetic vibration because temperature difference in the sample drastically decreased as soon as the vibration was excited in the sample. From these experimental results, the estimated mechanism in this process is that dendrite tips around the electrodes are cut off by the electromagnetic vibration in the initial stage of the solidification and it spread to the whole area of the sample by the convection induced by the electromagnetic vibration. Furthermore, nucleation is induced by an intense electromagnetic vibration.
  • M Suda, K Iwai, S Asai ISIJ INTERNATIONAL 45 (7) 979 -983 2005年 [査読無し][通常論文]
     
    Free surface behavior of a liquid metal under the imposition of a high frequency magnetic field has been examined. The high frequency magnetic field was generated by imposing a high frequency current on a coil surrounding the vessel filled with a liquid gallium. The magnetic field penetrated into a liquid gallium only from an upper surface due to the shielding effect of the copper vessel. A shallow standing wave on a free surface of a gallium was generated by a mechanical oscillator and its behavior was measured by a laser level sensor. The amplitude of the standing wave decreases with increase in the intensity and the frequency of the magnetic field. A damping behavior of the standing wave just after stopping the mechanical oscillation was also examined. The larger the intensity and the frequency of the magnetic field are, the more quickly the wave decays.
  • 鉄と鋼 91 (12) 856 -860 2005年 [査読無し][通常論文]
  • Control of Solidified Structure by using Electromagnetic Oscillation
    Materials Science Forum 477 2695 -2698 2005年 [査読無し][通常論文]
  • Control of Crystal Orientation of Hydroxyapatite by Imposing a High Magnetic Field
    Key Engineering Materials 284-286 75 -78 2005年 [査読無し][通常論文]
  • K Sugiura, K Iwai ISIJ INTERNATIONAL 45 (7) 962 -966 2005年 [査読無し][通常論文]
     
    Refining mechanism of solidified structure in which a static magnetic field and an alternating electrical current are simultaneously imposed on the local area of a metal or an alloy, has been experimentally examined using a Sn-10mass%Pb alloy. The refining period of the structure was examined by changing the imposing period of the electromagnetic vibration on the sample and it was confirmed that the refining period was the initial stage of solidification. The refining region was specified to be around the electrodes by inserting a stainless steel wire net in the sample while it was independent of the inserting position of the electrodes. Convection was induced by the electromagnetic vibration because temperature difference in the sample drastically decreased as soon as the vibration was excited in the sample. From these experimental results, the estimated mechanism in this process is that dendrite tips around the electrodes are cut off by the electromagnetic vibration in the initial stage of the solidification and it spread to the whole area of the sample by the convection induced by the electromagnetic vibration. Furthermore, nucleation is induced by an intense electromagnetic vibration.
  • M Suda, K Iwai, S Asai ISIJ INTERNATIONAL 45 (7) 979 -983 2005年 [査読無し][通常論文]
     
    Free surface behavior of a liquid metal under the imposition of a high frequency magnetic field has been examined. The high frequency magnetic field was generated by imposing a high frequency current on a coil surrounding the vessel filled with a liquid gallium. The magnetic field penetrated into a liquid gallium only from an upper surface due to the shielding effect of the copper vessel. A shallow standing wave on a free surface of a gallium was generated by a mechanical oscillator and its behavior was measured by a laser level sensor. The amplitude of the standing wave decreases with increase in the intensity and the frequency of the magnetic field. A damping behavior of the standing wave just after stopping the mechanical oscillation was also examined. The larger the intensity and the frequency of the magnetic field are, the more quickly the wave decays.
  • Control of Solidified Structure by using Electromagnetic Oscillation
    Materials Science Forum 477 2695 -2698 2005年 [査読無し][通常論文]
  • Control of Crystal Orientation of Hydroxyapatite by Imposing a High Magnetic Field
    Key Engineering Materials 284-286 75 -78 2005年 [査読無し][通常論文]
  • SQ Li, K Sassa, K Iwai, S Asai MATERIALS TRANSACTIONS 45 (11) 3124 -3129 2004年11月 [査読無し][通常論文]
     
    A novel process where a specimen is rotated during a slip casting under a high magnetic field has been proposed to fabricate highly textured ceramics. The usefulness of the newly proposed process has been confirmed in Si3N4 ceramics processing. In the substance which the magnetic susceptibility in a,b axis is higher than that in c-axis, chi(c) < chi(a,b,) one directional crystal orientation can not be obtained in a slip casting under a high magnetic field because the free choice of crystal orientation exists in a, b axis. The one directional crystal orientation Of Si3N4 with chi(c) < chi(a,b) has successfully been demonstrated in the new processing. The novel concept will provide a wide application to control the crystal orientation in various substances with the magnetic anisotropy of chi(c) < chi(a,b).
  • SQ Li, K Sassa, K Iwai, S Asai MATERIALS TRANSACTIONS 45 (11) 3124 -3129 2004年11月 [査読無し][通常論文]
     
    A novel process where a specimen is rotated during a slip casting under a high magnetic field has been proposed to fabricate highly textured ceramics. The usefulness of the newly proposed process has been confirmed in Si3N4 ceramics processing. In the substance which the magnetic susceptibility in a,b axis is higher than that in c-axis, chi(c) < chi(a,b,) one directional crystal orientation can not be obtained in a slip casting under a high magnetic field because the free choice of crystal orientation exists in a, b axis. The one directional crystal orientation Of Si3N4 with chi(c) < chi(a,b) has successfully been demonstrated in the new processing. The novel concept will provide a wide application to control the crystal orientation in various substances with the magnetic anisotropy of chi(c) < chi(a,b).
  • SUGIURA K, IWAI K ISIJ International 44 (8) 1410 -1415 2004年 [査読無し][通常論文]
  • ISIJ International (Iron and Steel Institute of Japan) 44 (8) 1410 -1415 2004年 [査読無し][通常論文]
  • S Kawai, Q Wang, K Iwai, S Asai MATERIALS TRANSACTIONS JIM 42 (2) 275 -280 2001年02月 [査読無し][通常論文]
     
    A new generating method of compression waves in a liquid metal has been proposed in which a static magnetic field and an alternating current are simultaneously imposed. The theoretical expressions of intensities and distributions of pressure and velocity accompanied with the compression waves have been derived. The pressure change in liquid gallium excited by the method proposed here was measured under different intensities of the magnetic field and the alternating current. The measured pressures approximately agreed with the theoretical evaluation. The structure of a Sn-Pb alloy that was solidified under the imposition of the compression waves, was completely refined.
  • S Kawai, Q Wang, K Iwai, S Asai MATERIALS TRANSACTIONS JIM 42 (2) 275 -280 2001年02月 [査読無し][通常論文]
     
    A new generating method of compression waves in a liquid metal has been proposed in which a static magnetic field and an alternating current are simultaneously imposed. The theoretical expressions of intensities and distributions of pressure and velocity accompanied with the compression waves have been derived. The pressure change in liquid gallium excited by the method proposed here was measured under different intensities of the magnetic field and the alternating current. The measured pressures approximately agreed with the theoretical evaluation. The structure of a Sn-Pb alloy that was solidified under the imposition of the compression waves, was completely refined.
  • S Amano, K Iwai, S Asai ISIJ INTERNATIONAL 37 (10) 962 -966 1997年 [査読無し][通常論文]
     
    In order to confirm the fact that compression waves can be generated in an electrically conductive liquid by using an electromagnetic field. Pressure oscillations in a liquid gallium were directly measured under the imposition of a high frequency magnetic field and a mathematical model based on the electromagnetic field theory and the compressible fluid dynamics has been developed. The pressure oscillation with the double frequency of the imposed magnetic field was not only isotropic but also in proportion to the square of the intensity of the magnetic field. these observations coincide with the prediction derived from the mathematical model. Furthermore, the measured distribution of the pressure oscillation in a liquid gallium agrees well with the result of the mathematical model.
  • Shinji Amano, Kazuhiko Iwai, Shigeo Asai ISIJ International 37 (10) 962 -966 1997年 [査読無し][通常論文]
     
    In order to confirm the fact that compression waves can be generated in an electrically conductive liquid by using an electromagnetic field. Pressure oscillations in a liquid gallium were directly measured under the imposition of a high frequency magnetic field and a mathematical model based on the electromagnetic field theory and the compressible fluid dynamics has been developed. The pressure oscillation with the double frequency of the imposed magnetic field was not only isotropic but also in proportion to the square of the intensity of the magnetic field. These observations coincide with the prediction derived from the mathematical model. Furthermore, the measured distribution of the pressure oscillation in a liquid gallium agrees well with the result of the mathematical model.

受賞

  • 2018年03月 日本鉄鋼協会 俵論文賞
     
    受賞者: 岩井 一彦
  • 2018年03月 日本鉄鋼協会 学術功績賞
     
    受賞者: 岩井 一彦
  • 2008年 日本鉄鋼協会 澤村論文賞
  • 2008年 第56回日本金属学会論文賞
  • 2005年 第53回日本金属学会論文賞
  • 2003年 日本鉄鋼協会「西山記念賞」
  • 2002年 第50回日本金属学会論文賞
  • 2001年 第49回日本金属学会論文賞

教育活動情報

主要な担当授業

  • ノーベルプロセシング工学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 材料プロセス、流体力学、電磁気学、移動現象制御
  • 材料科学特別演習
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 材料、環境、エネルギー、製造プロセス、評価、計測、解析
  • マテリアル製造工学特論
    開講年度 : 2021年
    課程区分 : 修士課程
    開講学部 : 工学院
    キーワード : 鉄鋼製造プロセス、鉄鋼材料の開発と加工、アルミニウム合金の特徴と製造プロセス
  • ノーベルプロセシング工学特論
    開講年度 : 2021年
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 材料プロセス、流体力学、電磁気学、移動現象制御
  • 材料科学特別研究
    開講年度 : 2021年
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 材料、環境、エネルギー、製造プロセス、評価、計測、解析
  • マテリアル製造工学特論
    開講年度 : 2021年
    課程区分 : 博士後期課程
    開講学部 : 工学院
    キーワード : 鉄鋼製造プロセス、鉄鋼材料の開発と加工、アルミニウム合金の特徴と製造プロセス
  • インターンシップⅠ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 学外実習、学外研修、国際経験
  • インターンシップⅡ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 学外実習、学外研修、国際経験
  • プレゼンテーション
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 文献読解、プレゼンテーション、質疑応答
  • 学外実習Ⅰ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 製鉄,材料製造
  • 学外実習Ⅱ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : インターンシップ
  • 科学英語演習
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 英語文献読解、プレゼンテーション、質疑応答
  • 移動速度論
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 移動現象、物質移動、熱移動、運動量移動、保存則
  • 材料工学演習Ⅴ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 物質移動、熱移動、運動量移動、相平衡、相変態、核生成、拡散・無拡散変態
  • 材料デザイン工学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 金属材料、電子、原子、結晶構造、機能性、構造材、表面、反応プロセス
  • 材料工学概論
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 金属材料、電子、原子、結晶構造、機能性、構造材、表面、反応プロセス
  • 環境と人間
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 全学教育
    キーワード : マテリアル製造、製造プロセス、省エネルギー、地球環境、持続的発展
  • マテリアルプロセス工学
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 材料熱力学、高温反応プロセス、非鉄金属の製造、座標系、反応操作、分離操作、分子運動論と真空科学技術
  • 材料工学演習Ⅲ
    開講年度 : 2021年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 二元系・三元系平衡状態図、自由エネルギー・組成図、材料熱力学、混合と相平衡、気体の関与する状態図、真空技術、活量、座標系、反応操作、分離操作、精錬反応


Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.