直流电弧热等离子体球化处理TA1粉末工艺研究

Study on the process of TA1 powder spheroidization by DC arc thermal plasma

摘要:

采用直流电弧热等离子体对不规则TA1粉末进行球化处理。利用金相显微镜、扫描电子显微镜、粒度粒形分析仪、霍尔流量计及氧氮分析仪等分析测试手段,研究球化工艺对粉末组织形貌、粒度、球形度、流动性、松装密度及氧含量的影响。结果表明,球化处理可将不规则形状TA1粉末球化为表面附着一层纳米颗粒的实心球形；粉末内部组织由等轴状α相转变为长条状α相。球化处理使TA1粉末平均粒径和氧含量降低,球形度升高。原料粉末粒度越小、等离子体发生器功率越高,球化后粉末平均粒径越小,球形度越高；但会导致球化后粉末中纳米颗粒含量升高、粉末流动性变差、松装密度降低；去除纳米颗粒可以提高粉末流动性,进一步降低氧含量。

关键词:热等离子体球化;钛合金粉末;功率;球形度;松装密度;流动性

Abstract:

In this work, the irregular TA1 powder was spheroidized by DC arc thermal plasma. Metallographic microscope, scanning electron microscope, particle size analyzer, Hall flowmeter and oxygen-nitrogen analyzer were used to study the particle size of raw material powder and the power of plasma generator in the process of spheroidization, and the effects on the microstructure, particle size, sphericity, fluidity, bulk density and oxygen content of the spheroidized powder. The results show that the irregular TA1 powder was spheroidized into solid spherical powder with uniform particle size after thermal plasma spheroidization. The surface was coated with a layer of nanoparticles. After spheroidization, the internal structure of the powder changed from the initial equiaxed α phase to the long strip α phase. The average particle size and oxygen content of TA1 powder decreased and the sphericity increased by thermal plasma spheroidization. The smaller the particle size of raw powder and the greater the power of plasma generator, the smaller the average particle size of spheroidized powder and the higher the sphericity, too small particle size of raw material powder and too high power of plasma generator will lead to the increase of nano-particle content in the powder after spheroidization, the deterioration of powder fluidity and the decrease of bulk density. After removing nanoparticles can improve the fluidity of powder.

Key words:thermal plasma spheroidization; titanium alloy powder; power; sphericity; loose density; liquidity