射频等离子体球化系统参数对制备球形Al2O3的影响

Effect of Main Operating Parameters on Al2O3 Spheroidization by Radio Frequency Plasma System

摘要:

以不规则Al2O3粉体为原料，采用TEKNA感应等离子体球化设备SY119-30kW制备微细球形Al2O3粉体，探究主要操作参数的影响，并研究了粉末的性能。结果表明等离子球化工艺制备的Al2O3粉体不仅表面光滑，而且球形度高，致密度高，流动性好。同时等离子体球化具有提纯的作用，球化后的粉体纯度都得到改善。 经XRD物相分析可知，分别采用Ar或者N2为鞘气都可以得到相同的物质组成，高温下N2并没有使得Al2O3氮化。不同的探针轴向位置对球化效果有较大的影响，必须保证针尖在等离子体中心位置。在反应腔体压力为负压的情况下，送分速率为65g/min时，粉体球化率可以达到100%，随着送分速率的增加，粉体球化率逐渐减小。反应腔室的压力对球化效果的影响也较大，其必须与载气流量保持协调。

Abstract:

Micro-fine spherical alumina (Al2O3) powders have been synthesized in this work with irregular feedstock materials by the SY119-30kW induction plasma sphroidization system. Effects of main operating parameters in fabrication process have been discussed and characteristics of the powders were investigated. The results show that the obtained powders with smooth surface exhibits fantastic sphericity, preferable density and better flowability. The purity of the fabricated powders has been improved and the phase compositions characterized by X-ray diffraction (XRD) shows the same results under different sheath gas (Ar or N2) conditions. Different axial positions of the injection probe strongly influenced the effectiveness of the treatment and Z=12.9cm would be the better choice for Al2O3 spheroidization in this experiment. The spheroidization efficiency of synthesized powders is almost 100% at feeding rate of 65g/min with the chamber pressure of 11.5psi (1atm=14.696psi), which decreases gradually as the feeding rate increases. The chamber pressure was also the vital factor that influenced the fabrication process and it should be coordinated with the carrier gas flow rate.