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

Micro-fine spherical alumina (Al2O3) powders with mean diameters of 7, 30 and 75 μm have been synthesized by the SY119-30kW 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.