INTERACTION FORCE BETWEEN PARTICLES SUSPENDED IN LIQUID METAL IN THE CASE OF TURBULENT AGGLOMERATION

夹杂物颗粒在液态金属中的团聚机理目前还不清楚，难以获得高洁净度的金属制品。以往对包裹体颗粒团聚过程的研究主要考虑了流体动力学对颗粒间碰撞的影响，而忽略了颗粒间相互作用力如货车范德华力的作用。本文主要研究了金属液湍流中夹杂物颗粒间的相互作用力对夹杂物颗粒团聚的影响.聚苯乙烯胶乳粒子在水溶液中的附聚实验：在搅拌的NaCl水溶液中，测量了粒径均匀、形状为球形的聚苯乙烯胶乳粒子（PSL）的附聚曲线。将由流体力学和颗粒间力组成的团聚理论计算得到的曲线应用于颗粒表面， 关于我们 通过测量附聚曲线，确定了表征货车范德华力的Hamaker常数。该值与文献值吻合较好。提出了一种新的预测团聚颗粒粒径分布的数学模型（分组模型）. SiC颗粒在水溶液中的团聚实验：以SiC颗粒为夹杂物颗粒模型，在搅拌的NaCl溶液中测量了SiC颗粒的团聚曲线。结果表明，团聚颗粒的破碎发生在团聚的后期。对分组模型进行了修正，加入了破碎现象，并采用实测的团聚曲线，确定了SiC的Hamaker常数，与文献值吻合较好. SiC颗粒在铝液中的团聚实验：构建了一种超声均质器，并成功地应用于SiC颗粒在铝液中的分散。在一些初步的实验中观察到的SiC颗粒在铝熔体湍流搅拌下的团聚。然而，由于再现性的问题，没有进行附聚的定量分析。研究了SiC颗粒在电磁搅拌下在铝液中的行为，观察到了SiC颗粒在电磁力作用下的分离过程。在实验中，使用了平均粒径为13μm和23μm的颗粒，并且在较大颗粒的情况下，发现在团聚之前进行分离。研究结果表明，颗粒间作用力在夹杂物团聚过程中的重要性，并为理解夹杂物颗粒在液态金属中的团聚机理提供了依据。少

The mechanism of the agglomeration of inclusion particles in liquid metal is not made clear enough for achieving the highly clean metal products. In the previous studies on the agglomeration of inclusion particles, the hydrodynamic effect on the collision between particles is taken into account, however, the role of inter-particle force such as van der Waals force has been disregarded, which is important for the process of particle agglomeration. In the present study, the following investigations have been made to make clear the role of inter-particle force in the agglomeration of inclusion particles in turbulent flow of liquid metal.1. Experiment on the agglomeration of PSL particles in aqueous solution : Agglomeration curves of polystyrene-latex particles (PSL) which had a uniform size and spherical shape were measured in an agitated NaCl-aqueous solution. By applying the calculated curve obtained by the agglomeration theory composed of hydrodynamics and inter-particle force on the m … More easured agglomeration curves, the Hamaker constant, the characteristic of the van der Waals force, was determined. This value agreed well with the literature value of PSL. A mathematical model (grouping model) was newly developed to estimate the size distribution of agglomerated particles by a simple procedure.2. Experiment on the agglomeration of SiC particles in aqueous solution : SiC particle was used as the model of inclusion particle and agglomeration curves were measured in an agitated NaCi solution. It was found that the breakup of agglomerated particles took place in the later stage of agglomeration. The grouping model was modified to include the breakup phenomenon and adopted measured agglomeration curves, and as a result, the Hamaker constant of SiC was determined, which agreed with the literature value.3. Experiment on the agglomeration of SiC particles in molten aluminum : An ultrasonic homogenizer was constructed and adopted successfully to the dispersion of SiC particles in molten aluminum. Agglomeration of SiC particles in the molten aluminum under turbulent agitation was observed in some preliminary experiments. However, quantitative analysis of agglomeration was not carried out because of the problem of the reproducibility. The behavior of SiC particles in molten aluminum was investigated under the electromagnetic agitation and the separation of particles by the electromagnetic force was clearly observed. In the experiment, particles with 13μm and 23μm in average diameter were used, and in the case of larger particle, separation was found to proceed before agglomeration. On the contrary, the smaller particle was found to agglomerate first and then be separated.In conclusion, the importance of inter-particle force in the inclusion agglomeration was made clear and the measure for understanding the mechanism of inclusion particles in liquid metal was given in this study. Less