钽粉等离子体球化及其球化过程中卫星粉的形成机制

Plasma Spheroidization of Ta Powder and Formation Mechanism of Satellite Powder in the Process of Spheroidization

微米级钽粉(Ta)在生物医疗增材制造和其它制造领域具有广阔的应用前景。采用射频热等离子体对不规则钽粉进行球化处理以改善其流动性,对等离子体球化处理前后的钽粉进行了表征,并分析了球化过程中卫星粉的形成过程与机制。结果表明,经等离子体球化后的钽粉具有较为理想的球形度和光滑的表面,其霍尔流动性和表观密度分别从13.6 s·(50 g)^(-1)提高到6.73 s·(50 g)^(-1)和6.83 g·cm^(-3)提升至9.06 g·cm^(-3),钽粉的球化率和球形度分别可约达95.2%和0.92;球化过程中卫星粉的形成主要是因液滴的碰撞所致,且随着送粉速度的增加,液滴碰撞概率增大,液滴的凝并使球形颗粒的粒径增大。

Micron tantalum powder(Ta) has broad application prospects in biomedical additive manufacturing and other manufacturing fields. The irregular tantalum powder was spheroidized by RF thermal plasma to improve its fluidity. The tantalum powder before and after plasma spheroidization was characterized, and the formation mechanism of satellite powder in the process of spheroidization was analyzed. The results show that the tantalum powder after plasma spheroidization has ideal sphericity and smooth surface, and its Hall fluidity and apparent density are increased from 13.6 s·(50 g)^(-1)to 6.73 s·(50 g)^(-1)and from 6.83 g·cm^(-3)to 9.06 g·cm^(-3), respectively. The spheroidization rate and spherical degree of tantalum powder can reach about 95.2% and 0.92, respectively. The formation of satellite powder in the spheroidization process is mainly caused by the collision of droplets, and with the increase in powder feeding rate, the collision probability of droplets increases, resulting in larger particle size of spherical particles due to the droplet condensation.