Experimental and Numerical Analysis of a Reverse-polarity Plasma Torch for Plasma Atomization
Experimental and Numerical Analysis of a Reverse-polarity Plasma Torch for Plasma Atomization
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DOI：
10.1007/s11090-021-10181-8
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发表时间：
2021-05
影响因子：
3.6
通讯作者：
Zhengxin Yin;Deping Yu;Qingbo Zhang;Shengyuan Yang;Tong Yang
中科院分区：
文献类型：
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作者：
Zhengxin Yin;Deping Yu;Qingbo Zhang;Shengyuan Yang;Tong Yang
等离子体雾化（PA）是一种高度认可的用于增材制造和金属注射成型的球形粉末生产方法。它使用多个会聚等离子射流同时熔化和雾化金属线成球形粉末。雾化粉末的质量在很大程度上取决于产生等离子体射流的等离子炬。虽然反极性等离子体炬（RPT）已在等离子体材料中实现了商业化应用，但其工作特性与等离子体材料所需的高稳定性、高热效率和高温超声速等离子体射流有关。因此，对自制的PA用RPT进行了实验和数值研究，以揭示其伏安特性、热特性和射流特性。结果表明，电弧电压波动在10 V以内时，RPT工作稳定，制备的粉末质量均匀。此外，与普通氩等离子炬相比，RPT工作在高电弧电压和低电弧电流下，对电极的侵蚀更小，粉末更纯净。RPT的热效率和等离子体射流的平均焓分别大于70%和3 × 106J/kg，是产生高能量密度等离子体射流的理想材料。此外，数值结果表明，采用De-Laval喷嘴的RPT可以产生足够高温度的超声速等离子体射流，使大多数材料熔化和雾化。最后，PA实验证明了RPT在生产表面光滑、球度高、粒度小的高质量粉末方面的有效性。
Plasma atomization (PA) is a highly recognized method for producing spherical powders for additive manufacturing and metal injection molding. It uses multiple converging plasma jets to simultaneously melt and atomize the metal wire to spherical powders. The quality of the atomized powders is highly dependent on the plasma torch for generating the plasma jet. Although the reverse-polarity plasma torch (RPT) has been commercially applied in the PA, its working characteristics relating to the high stability, high thermal efficiency, and supersonic plasma jet with high temperature desired in the PA are unclear. Therefore, experimental and numerical investigations of a self-manufactured RPT for PA were conducted to reveal its volt-ampere, thermal and jet characteristics. Results showed that the RPT works stably with the arc voltage fluctuation within 10 V ensuring the uniform quality of the produced powders. Besides, compared with the common argon plasma torch, the RPT works at high arc voltage and low arc current leading to less erosion of electrodes and purer powders. Furthermore, the thermal efficiency of the RPT and the mean enthalpy of its plasma jet is higher than 70% and 3 × 106J/kg respectively, making it ideal for generation of the plasma jet with high energy density. Moreover, numerical results showed that the RPT with the De-Laval nozzle can generate supersonic plasma jet with temperature high enough for melting and atomizing most of materials. Finally, the PA experiment showed the effectiveness of the RPT for the production of high quality powders with smooth surfaces, high sphericity and small particle size.