용융방사법을 이용한 알루미늄 섬유의 연속주조에 관한 연구
(A) Study on the continuous casting of Al fiber by melt extraction method
용융방사법 알루미늄섬유 연속주조 재료공학;
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Direct casting of continuous metallic fibers by melt extraction has no widespread industrial application despite the economical advantage of the process. The main reason for this is due to the instability of molten metal, when contact to the wheel. The behaviour of the molten metal is controlled by inertia and surface tension in the melt extraction. This causes a much lower stability of the molten metal and results in rough surface of metallic fiber. The rotation of the wheel dynamically induces a meniscus and this is governed by the surface tension of the melt. The meniscus stability is the most important thing in this process. For establishment of continuos fiber casting is need to maintain the meniscus stability. The meniscus was easily broken up, when increase of wheel speed and up to 0.7mm/min feeding speed. In order for fibers to be extracted from the melt, the rotational speed of wheel must overcome the surface forces acting on the meniscus. therefore, impact from wheel could be propagated to meniscus. This study has been purposed for continuos casting of Al fibers. In order to maintain the stability of the process, it should be recommended to remove the process instabilities, such as Rayleigh wave, Kelvin-Helmholtz instability and adhesion between wheel and solidified molten melt. The aluminum and aluminum-silicon alloy fibers were fabricated by melt extraction process, during variation of wheel speed, melt temperature and feed speed. The melt-extracted fibers typically show a sickle or kidney shaped cross-section. Mean equivalent fiber diameters and length are 200-250㎛ and 60-80mm, respectively. Surface of fibers were investigated by image analyzer and SEM. in order to observe the several defects from instabilities of the process.