| Research Abstract |
Compression waves have attractive functions in liquid metal processes such as refinement of solidified structure, degassing, promotion of reaction rate and so on. However, they have not been used in industry because of the power limitation of electrostrictive or magnetostrictive vibrators, dissolution of power transmitter contacting with a liquid metal. On the other hand, compression waves can also be excited in a liquid metal by using an electromagnetic field. This method can solve problems mentioned above. That is, we can excite large power compression waves under non-contacting operation. In this research, electromagnetic excitation methods of compression waves have been proposed and industrially useful function of compression waves excited by the proposed method in solidification processing has been demonstrated in the experiment. One of the excitation method proposed here is the simultaneous imposition of a static magnetic field and an alternating magnetic field on a liquid metal
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and the other one is the simultaneous imposition of a static magnetic field and an alternating electric current. In both cases, excitation of compression waves was theoretically and experimentally confirmed. Furthermore, refined macrostructure of the Sn-Pb alloy was obtained under the imposition of compression waves excited by the latter method during solidification.
Alfven waves have been mainly studied in the field of astrophysics since it was very difficult to excite on the earth. However, under the development of super conducting technology, we can excite them in a liquid metal. Therefore, Alfven waves have a possibility as a process control tool. Here, excitation method of Alfven waves in a liquid metal has been investigated theoretically and experimentally. Pressure distribution accompanying Alfven waves in a liquid metal was theoretically derived and it was compared with the measured pressure in the metal. The both results shows a good agreement. Then, the newly proposed method is useful to excite Alfven waves. Furthermore, refined macrostructure of the Sn-Pb alloy was obtained under the imposition of Alfven waves during its solidification. Less
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