Fragmentation and solidification of fusible alloy melt by water spray
Fragmentation and solidification of fusible alloy melt by water spray
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DOI：
10.1016/j.powtec.2022.117778
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发表时间：
2022-08
影响因子：
5.2
通讯作者：
Wataru Hikita;Shodai Hirayama;C. Inoue;Zhen-yu Wang;M. Nakaseko;Takuya Takashita
中科院分区：
文献类型：
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作者：
Wataru Hikita;Shodai Hirayama;C. Inoue;Zhen-yu Wang;M. Nakaseko;Takuya Takashita
为了从热流体的角度阐明金属粉末生产过程中发生的破碎和凝固过程，我们进行了实验，以可视化熔融 42 Sn-58 Bi 易熔合金的水雾化，并测量了所得金属粉末的圆形度。清晰地捕捉到了压力高达 5 MPa 的完全开发的快速水喷雾内部的破碎过程。时间分辨图像揭示了碎片模式，涉及因飞溅、蒸汽爆炸和分裂而延伸的熔融韧带。韧带颈部直径变细的时间变化表明，破碎速度是由熔滴本身的毛细管现象控制的，凝固和粘度对夹点动力学没有影响。所生产的金属粉末表现出与尺寸相关的圆形度，较大颗粒往往比较小颗粒的球形度较差。该机制归因于不均匀凝固，这种凝固在液滴的收缩部分得到增强，与获得的图像非常一致。
To elucidate the fragmentation and solidification processes that occur during the production of metal powders from a thermo-fluid perspective, we conducted experiments to visualize the water atomization of molten 42 Sn–58 Bi fusible alloy and made measurements of the circularity of the resulting metal powder. The fragmentation process inside a fully developed fast water spray with a pressure up to 5 MPa was clearly captured. The time-resolved images revealed fragmentation patterns involving extending molten ligaments resulting from splashing, vapor explosions, and splitting. The time variation of the thinning of the neck diameter of the ligaments revealed that the fragmentation is rate-controlled by the capillarity of the molten drop itself, and solidification and viscosity have no influence on the pinching-point dynamics. The produced metal powder displayed size-dependent circularity, and larger particles tended to be less spherical than small particles. The mechanism is attributed to non-uniform solidification, which is enhanced at the pinching part of a droplet, consistent well with the images obtained.