Abstract
In order to produce high quality metals, decreasing of the amount of non-metallic inclusions is indispensable. A new elimination method of non-metallic inclusions using electromagnetic force is proposed. The principle of the method is that the electromagnetic force induced in molten metal by imposing direct electric current and magnetic field, scarcely acts on the non-metallic inclusions due to the low electrical conductivity. Thus, the non-metallic inclusions move in the opposite direction to that of the electromagnetic force. In order to confirm the principle of the method, the movement of polystyrene particles suspending in a NaCl aqueous solution by electromagnetic force is visualized. Moving velocity of the polystyrene particles is compared with the theoretical one. The turbulent fluid motion caused by unevenly distributed electromagnetic force agitates the inclusions which have to be eliminated by the electromagnetic force and makes the principle of the method useless. Thus, the suppression of the turbulent motion is essential and therefore, the molten metal has to be passed through porous bricks or a bundle of thin pipes under the electromagnetic force. That is, the turbulent motion of molten metal causing in the unevenly distributed electromagnetic force is substantially surpressed so as not to influence the effect of elimination of inclusions, because the turbulent motion is bounded in small spaces such as the pore in the brick or thin pipe. The usefulness of the method is demonstrated by the experimental works using molten tin including the non-metallic inclusions of Al2O3 or intermetallic compounds.
