射频等离子体球化系统参数对制备球形Al_2O_3的影响（英文）

Bfect of Main Operating Parameters on Al_2O_3 Spheroidization by Radio Frequency Plasma System

以不规则Al_2O_3粉体为原料,采用TEKNA射频感应等离子体球化设备SY119-30kW制备不同粒度的(7,30,75μm)微细球形Al_2O_3粉体,并研究了主要操作参数的影响。结果表明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,即Z=12.9cm。等离子球化工艺制备的Al_2O_3粉体不仅表面光滑,而且球形度高,致密度高,流动性好。在反应腔体压力为负压P=0.079 MPa的情况下,送分速率为65 g/min时,粉体球化率可以达到100%;反应腔室的压力对球化效果的影响较大,其必须与载气流量保持协调。经XRD物相分析可知,分别采用Ar或者N_2为鞘气都可以得到相同的物质组成,高温下N_2并没有使Al_2O_3氮化。同时,等离子体球化具有提纯的作用,球化后的粉体纯度得到改善。

Micro-fine spherical alumina（Al2O3） powders with mean diameters of 7,30 and 75 μm have been synthesized by the SY119-30 kW radio frequency induction plasma spheroidization system.The effect of main operating parameters on spheroidization process was investigated.The results show that different axial positions of the injection probe strongly influence the effectiveness of the spheroidization treatment and Z=12.9 cm is the best position for Al2O3 spheroidization process as it is the middle of coil center for this spheroidization system.The obtained powders with smooth surface exhibit fantastic sphericity and preferable density.The spheroidization efficiency of synthesized powders is almost 100%at feeding rate of 65 g/min with the chamber pressure of 0.079 MPa.In addition,the chamber pressure is also the vital factor that influences the fabrication process and it should be coordinated with the carrier gas flow rate.The phase compositions characterized by X-ray diffraction（XRD） shows the same results under different sheath gas（Ar or N2） conditions.Furthermore,the purity of the fabricated powders is improved after high temperature spheroidization treatment.