铝熔体高频电磁净化效率研究

【作者】 秦学智；

【导师】 曹志强；

【作者基本信息】 大连理工大学 ， 材料加工工程， 2004， 硕士

【摘要】 由于电磁净化技术的夹杂去除效率比传统的净化技术，如泡沫陶瓷过滤技术等要高得多，甚至能对钢中约2μm的非金属夹杂物产生显著的作用，因此有着诱人的发展前景。可是，电磁净化技术如果不能实现在线连续处理，就无法用于工业生产。近年来，有关电磁连续净化的研究很多，却未见有任何突破性进展。本文用浇注法对各个净化参数与净化效率的关系进行了研究，在此基础上，为电磁连续净化的发展方向指出了一条理想的道路。 本文考查了圆形分离管管径、分离时间和功率等参数对净化效率的影响，优化出了在本实验条件下既能保证较好分离效果，又能保证较高生产效率的分离参数，并结合实验，研究了螺线管内部轴向与径向的净化效率分布。 比较了圆形、方形和三角形分离管的净化效率，指出，在本实验条件下，圆形管分离效率最大，三角形和正方形管相差不大，效率均较低。三角形和正方形分离管的净化效率受时间和功率的影响不大。 利用电子探针，研究了电磁净化过程中试样径向夹杂物的迁移和分布规律，进一步证实了电磁净化使非金属夹杂物向分离管边缘聚集的现象。而且通过测量心部初晶硅颗粒的大小，证明了在本实验条件下，净化30s时，试样中心区初晶硅颗粒粒径最大约8μm；当净化时间延长到60s时，中心区初晶硅颗粒粒径可达1μm左右，这比泡沫陶瓷过滤法只能滤去10μm以上夹杂物颗粒要好得多。 最后，设计了一套理想化的电磁连续净化方案。在设计电磁连续净化方案时，计算比较了各种形状分离管对金属液粘滞阻力的大小，解释了净化效果沿轴向呈“周期性”分布的原因并提出相应改善措施。为了提高生产效率，分离线圈中须放置多个分离管，同时应联接多个线圈以增加分离管的数目。在所设计的理想净化方案中，创造性地使分离出的非金属夹杂物与被净化的洁净金属液连续不断地从不同的通道排出，避免了反复更换分离管，实现了在线净化的真正连续性。更多还原

【Abstract】 Influences of separating tube diameter, separating time and power on purifying efficiency are examined, then the best purifying project is optimized out. The distribution state of electromagnetic field inside solenoid is calculated, and on the basis of experiments, purifying efficiency is studied along the axis and radial of solenoid.After purifying efficiencies of round, square and triangle separating tubes are compared, a truth is educed: purifying efficiency of round tube is maximal, and that of square and triangle separating tube is much lower.With the help of electronic probe, movement and distribution of nonmetal occluded foreign substances along radial during the process of electromagnetic purifying are studied. Under the experiment condition of the dissertation, when the eutectic alloy Al-24%Si is purified about 60 seconds, the grain diameter of primary crystal Si grains in center areas of samples can be reduced to lMm or so.In the last chapter, three problems are figured out: firstly viscous resistances to metal fluid of separating tubes of various shapes are calculated; secondly the reason of periodical distribution of purifying effect along tube axis is made clear and accordingly some improvement measures are brought forward. At last on the basis of foregoing content, an ideal continuous electromagnetic purifying project is designed, in which the nonmetal occluded foreign substances that are separated out from metal melt, and the clean metal fluid that is purified by high-frequency electromagnetic field, can continuously are discharged from different channels. So the purifying project not only avoids the trouble of repeatingly replacing separating tube, but also realizes the real on-line continuity.更多还原