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Free surface motion of a liquid metal submerged in an alternating magnetic field has been examined. A copper vessel filled with a liquid gallium is set in a coil for the imposition of the alternating magnetic field. The alternating magnetic field penetrates into a liquid gallium only from an upper free surface because thickness of the copper vessel is larger than the electromagnetic skin layer of copper. Time variation of displacement of the standing wave loop excited on the free surface is detected by a laser level sensor. The standing wave was suppressed not only by intensification of the magnetic field magnitude but also increase of the magnetic field frequency.

A high magnetic field is a useful tool to control the crystal alignment of ceramic materials. In this study, a horizontal 10T static magnetic field was imposed on slurry containing hydroxyapatite (HAp) crystals under the horizontal mold rotation during slip casting process so as to introduce uni-axial alignment for some amount of crystals in the sample, and then it was sintered in atmosphere without the magnetic field. From X-ray diffraction, it has been found that the HAp crystals in the sample treated with the mold rotation under the magnetic field were aligned its c-axis to a particular direction.

Formation of crystallographically orientaed hydroxyapatite (HAp) 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 high magnetic field and sample rotation are simultaneously imposed on the hydroxyapatite during a slip casting process in order to align its c-plane within a horizontal plane. From X-ray diffraction, it has been found that the HAp crystals in the sample treated with the magnetic field and the sample rotation were oriented to a particular direction in the slip casting process 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 sample rotation was not observed before and after the sintering.

A high magnetic field is a useful tool to control the crystal alignment of non-magnetic materials such as ceramics and polymers. In the case of Hydroxyapatite crystal, the a,b-axis is aligned parallel to the direction of an imposed magnetic field. This fact implies that the alignment of the c-axis is not controllable only using a high static magnetic field due to the freedom of the c-axis in a plane perpendicular to a magnetic field direction. In this study, a high static magnetic field and mold rotation was simultaneously so applied during a slip casting process as to align the c-axis of HAp poly crystals.

The controlled development of texture microstructure in ceramics is one effective way to improve their properties, such as electrical, mechanical properties and biocompatibility. A bioceramics with oriented crystal structure has attracted great interest. In bone reparations, Hydroxyapatite (HAp)-based biomaterials were frequently used. And HAp is the main mineral constituent of the hard tissue of human bodies, which occurs with a hexagonal crystal. A HAp crystal turns out to have different surface properties in a- (or b-) plane and c-plane. In this regard, to get highly oriented HAp is very important before using HAp as a biomaterial. And the crystal orientated HAp is useful not only as biomaterials but also as protein absorbents. In this research, two different kinds of HAp-based biomaterial with oriented structure (HAp bioceramics and HAp-coated titanium composite) were studied.

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Abstract: A hybrid process combining a cold crucible and a nontransferred plasma has been proposed. By using this process, not only metals with a high melting point but also dielectric materials can be melted without contamination. Also, good homogeneity of alloying elements can be expected by using this process because of the induction mixing taking place in the molten charge. By using the hybrid process, silicon was melted and held with almost no contact with the crucible. A heat-transfer analysis taking account of the dependence of electrical conductivity on temperature was performed on a silicon charge as a semiconductor. The effects of operating parameters, such as magnetic flux density, radius of the charge, and frequency of the coil current, were studied on the equilibrium temperature at which the heat generation rate in a charge balances with the heat removal rate. The critical temperature over which induction heating is possible was theoretically derived and was compared with the value obtained in an experiment.

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\circin the synchronous region. The minimum alignment time is the same as that under the imposition of a static field.

A static magnetic field and an alternating current are imposed on a metallic alloy during solidification for a crystal alignment of the primary phase. A Sn-10%Pb is selected as a sample because its primary phase is expected to have an anisotropic nature in magnetic susceptibility. In the x-ray diffraction pattern of the sample solidified without the magnetic field, the first and second highest peaks are (101) and (211) planes. On the other hand, those solidified with the magnetic field are (200) and (220) planes which are magnetically preferred planes. That is, the primary phase crystals in the sample solidified with the magnetic field are aligned to the specific direction.

Mass transfer near the reaction interface is often rate determining step in a high temperature process. Traditional agitation method reduces concentration boundary layer formed near the reaction interface from its outside by increasing the velocity in the bulk region. On the other hand, agitation in the concentration boundary layer is another way for intensification of the chemical reaction rate. For this purpose, excitation of flow in the concentration boundary layer is essential. Thus, effect of the static magnetic field on the solute concentration distribution near an electrode under the AC current imposition has been experimentally examined in this study. In the experiment, brightness near the interface between the copper electrode with the triangle shape and the mixed solution of 0.5mol/L CuSO4 aqueous solution with 0.1mol/L H2SO4 aqueous solution was measured under the imposition of the AC electrical current of 4Vp-p and 0.5Hz. And the aqueous solution motion was estimated using polystyrene particles. As the results, the concentration boundary layer thickness decreased and the AC current concentrated around the top of the lower electrode by imposing the static magnetic field.

An electromagnetic vibrating force is a candidate of a micro-size inclusion removal method [1-5]. Especially, an A.C. magnetic field imposition has an advantage that it enables the inclusion removal and an induction heating of a molten steel in a tundish simultaneously [3-5]. However, appropriate system design and operating conditions for the simultaneous operation of the inclusion removal and the induction heating of the molten steel by the A.C. magnetic field imposition have not been clarified. Therefore, an inclusion removal time from the molten steel under the A.C. magnetic field imposition has been calculated in this study. And then, a minimum channel length for the inclusion removal and the molten steel temperature increase per unit channel length by the induction heating has been evaluated. The A.C. magnetic field frequency should be controlled within a certain frequency range in which the inclusion removal time becomes minimal. Furthermore, the channel length should be longer than the minimum channel length for the inclusion removal calculated by using the minimum inclusion removal time and an assumed maximum molten steel velocity in the channel. The molten steel temperature increase per unit channel length by the induction heating can be controlled by controlling the A.C. magnetic field frequency within the frequency range suitable for the inclusion removal. Especially, a high frequency condition in that frequency range is better for the efficient thermal supply in this calculation condition.

A new magnetically assisted wastewater treating system has been suggested for CrVI-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.