直流电弧热等离子体球化处理TA1粉末工艺研究

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、霍尔流速计、斯科特容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、粒度分布、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亚微米颗粒的实心球形;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亚微米颗粒含量增加、粉末流动性变差、松装密度降低;去除亚微米颗粒可以提高粉末流动性,并进一步降低氧含量。     

超瞬态凝固增材制造梯度整体涡轮叶盘用高温合金粉末特性研究I：盘体用合金粉末

本文针对超瞬态凝固增材制造梯度整体涡轮叶盘用高温合金粉末特性开展研究。根据合金的承温能力和JMatPro相平衡计算结果,分别选用GH4169和K418作为盘体心部和轮盘边缘部位材料,DZ4125作为叶片材料。采用真空感应熔炼氩气雾化制粉(VIGA)制备高温合金粉末,筛分至53-105μm粒度范围,采用差示扫描量热分析（DSC）、场发射扫描电镜（FESEM）、电子探针（EPMA）、激光粒度仪、动态图像粒度粒形分析仪以及综合粉体性能测试仪对高温合金粉末的相变温度、显微组织、元素偏析行为、粒度、粒形、松装密度、振实密度和流动性进行了系统表征。结果表明：K418合金固液温度范围比G4169合金窄,K418合金的γ′和MC碳化物的开始析出温度均比GH4169高,过渡区(GH4169+K418)混合成分合金主要强化相的析出温度介于GH4169和K418两种合金之间。GH4169和K418合金粉末形貌主要为球形和近球形。表面和截面显微组织主要呈树枝晶结构,所含元素中偏析倾向较强的元素有Ti、Nb、Zr和Mo,均富集分布于枝晶间,而偏析倾向弱的元素包括Ni、Cr、Fe和Al,高温合金粉末元素偏析类型与铸造镍基高温合金相近,但粉末组织更为细小均匀。激光衍射和动态图像分析法测得的粉末粒度值接近,GH4169的D50分别为79.1μm和76.2μm,K418的D50分别为67.8μm和65.6μm。动态图像法测得2种合金均具有较好的球形度,GH4169和K418的SPHT均值分别为0.91和0.90。所选GH4169和K418高温合金粉末具有相近的松装密度、振实密度和流动性,其松装和振实密度分别达到合金理论密度的50%和60%,压缩度在13.3~15.5%范围,粉末具有较好的流动性（18.5~20.4 s?(50 g)-1）。     

射频等离子体制备球形钨粉的研究

通过射频等离子体球化处理工艺,以不规则形状钨粉为原料,制备了球形钨粉,并研究了加料速率和粉末粒度对粉末球化率的影响。采用扫描电子显微镜、X射线衍射和激光粒度分析仪对球化处理前后粉末的形貌、物相和粒度分布进行了测试和分析。结果表明：粒度在5.5~26.5 μm范围的不规则形状钨粉,经等离子球化处理后得到表面光滑、分散性好、球化率可达100%的球形钨粉。球化处理后,粉末的粒度略微增大。随加料速率的增加,钨粉的球化率降低。随着钨粉球化率的提高,粉末的松装密度和流动性得到显著改善。松装密度由6.80 g/cm3 提高到11.5 g/cm3,粉末流动性由14.12 s/50 g提高为6.95 s/50 g     

感应等离子体制备高纯致密球形钼粉研究

利用感应等离子体技术制备出高纯致密球形钼粉,实现了钼粉的球化、致密化、细化和纯化,同时研究了感应等离子体功率和原料粉粒度对球化率的影响。采用扫描电子显微镜、X射线衍射仪和激光粒度分析仪对球化处理前后粉末的形貌、物相和粒度分布进行测试和分析。结果表明,形状不规则的原料钼粉,经等离子体球化处理后得到球形度好、表面光滑、分散性良好、球化率几乎可达100%的球形钼粉。球化处理后,钼粉粒度变细,且粒度分布更集中。相同工艺条件下,随着等离子体功率的增加,钼粉的球化率先增大后降低,当等离子体功率为25 kW时钼粉球化效果最好,粒度较小的钼粉球化率较高。随着钼粉球化率的提高,粉末的流动性得到显著改善,松装密度也得到提高。钼粉末的流动性由40 s/50 g提高为11 s/50 g,松装密度由2.3 g/cm~3提高到6.1 g/cm~3。     

射频等离子体法制备球形化TC4(Ti6Al4V)合金粉末（英文）

采用射频等离子体法制备了高度球形化的TC4(Ti6Al4V)合金粉末。主要探究仪器送粉喷嘴高度、产生等离子体的功率、反应室的压力、原料粉体的粒度分布、送粉速率以及载气的气流速率等对于粉体球化率的影响。通过SEM图像观察粉体的形貌变化并计算粉体的球化率,利用XRD图谱测定球化前后粉体相结构。结果表明,通过观察球化粉末横截面可知粉末为实心球体且表面光滑,球化后粉末流动性明显提高,松装密度增大,粒度分布变窄,适合3D打印等应用技术对于合金粉体的要求。实验中,调节送粉喷嘴高度为12.5 cm,反应室压力为101.36 kPa,送粉速率为1.742 g/min,产生等离子气的功率为27.2 kW且控制原料粉体的粒度分布在38～63μm时,可使得球化率达到99%,明显高于其他球化粉末制备方法。     

球形TC4合金粉末的制备、表征及雾化机理

采用真空气体雾化法制备了TC4合金粉末,并采用激光粒度分析仪、扫描电子显微镜和霍尔流速计等对制备的粉末粒度分布、组织形貌、松装密度、流动性等进行了测试分析。结果表明:真空气体雾化法制备的TC4合金粉末粒度呈正态分布,尺寸集中分布在32.52～182.50μm左右,粉末中值粒径d_(50)为92.70μm,粉末球形度高,氧含量低(0.14%);粉末具有较低的松装密度和良好的流动性,粒径在38～106μm的粉末其流动性为25～50 s/(50 g),松装密度为2.52～2.56 g/cm~3。TC4合金粉末中粒径较大的颗粒表面呈发达的近似等轴的胞状枝晶组织,而颗粒粒径越小,其表面越光滑。少部分小颗粒粘附在大颗粒表面上,出现连体的"卫星"状。     

Spheroidization of Nd-Fe-B Powders by RF Induction Plasma Processing

以不规则形的钕铁硼粉为原料,使用射频等离子体球化处理工艺,制备球形钕铁硼粉.研究了原料的加料速率和粉末粒度对粉末球化率的影响.通过扫描电子显微镜观察对比了等离子球化处理前后粉末及截面形貌,采用X射线衍射方法测试分析了球化过程中氧化物的生成.检测了球化前后粉末的松装密度及其粒度分布.结果表明:不规则形状的钕铁硼粉经等离子球化处理后其球化率可达到100％,松装密度由2.778 g/cm3提高到3.785 g/cm3,粉末流动性由43.3 s/50 g提高到27.5 s/50 g.该粉末适用于凝胶注膜成型及注射成型.     

球形钨粉的制备及应用

球形钨粉以其良好的流动性、高的松装密度和振实密度广泛应用于喷涂、增材制造等材料制备领域。本文以不规则形状钨粉颗粒为原料,采用射频等离子球化技术制备球形钨粉,并对球形钨粉进行铺粉及成形实验效果评价。在射频等离子球化过程中,研究球化工艺参数（送粉速率、送粉位置）和原料粉末形态对球化结果的影响。在铺粉实验方面,研究粉末特征和铺粉层厚对铺粉效果的影响。采用扫描电子显微镜、激光粒度分析仪和BT-100粉体综合特性测试仪对球化处理前后粉末的形貌、粒度、流动性、松装密度和振实密度进行测试和分析。结果表明：经过球化处理后,钨粉颗粒呈规则球形,表面光滑,球化率可达100%,流动性、松装密度和振实密度得到明显提高。球化率高的粉末流动性好,铺粉效果好;随着层厚的增加,铺粉效果逐渐得到改善;采用合适粒径的球形钨粉打印的钨薄壁件表面相对光洁,尺寸精度高。     

射频等离子体方法制备球形化TC4 (Ti6Al4V)合金粉末

本文通过射频等离子方法制备了高度球形化的TC4(Ti6Al4V)合金粉末。主要探究仪器送粉喷嘴高度、产生等离子体的功率、反应室的压力、原料粉体的粒径分布、送粉速率以及载气的气流速率等对于粉体球化率的影响,通过调节上述因素形成对比实验并得到不同实验条件下的球化粉体。通过SEM图像可观察粉体的形貌变化并计算比较粉体的球化率,通过XRD图可知球化前后粉体相结构不发生变化,观察球化粉末横截面可知粉末为实心球体且表面光滑,同时可发现球化后粉末流动性明显提高,松装密度大,粒径分布窄,适合3D打印等应用技术对于合金粉体的要求。实验中,调节送粉喷嘴高度为12.5cm,反应室压力为14.7psia,送粉速率为1.742g／min,产生等离子气的功率为27.2kW且控制原料粉体的平均粒径在38～63微米时可使得球化率达到99%,明显高于其他球化粉末制备方法。     

选区激光熔化成形用钽粉的射频等离子体球化

以不规则状钠还原钽粉为原料,采用射频等离子体球化技术制备高纯致密球形钽粉,实现了还原钽粉的球化、致密化和纯化。研究了送粉速率、载气流量、反应室压力等工艺参数对钽粉球化率及粉体特性的影响,并探索了球化钽粉的选区激光熔化成形适用性。结果表明:不规则状钠还原钽粉,经射频等离子体球化处理后可得到表面光滑、内部致密、高纯低氧、球化率可达100%的球形钽粉。球化处理后,钽粉粒度分布变窄。钽粉的球化率随送粉速率的增大而降低,随载气流量的增加先升高后降低。弱负压更有利于获得较高球化率的钽粉。随着球化率的提高,钽粉的流动性能显著改善,松装密度与振实密度明显提高。当送粉速率为30 g/min,载气流量为5.0 L/min,反应室压力为82.7 kPa时,球形钽粉霍尔流速提高到5.98 s/50g,与不规则形钠还原钽粉相比,松装密度由3.503 g/cm~3提高到9.463 g/cm~3,振实密度由5.344g/cm~3提高到10.433g/cm~3,且氧含量由0.076%降低至0.0481%。另外,射频等离子体球化钽粉具有良好的选区激光熔化成形适用性,其试样致密度ρ≥99.5%,抗拉强度σ_b=693 MPa,屈服强度σ_(0.2)=616 MPa,延伸率δ=28.5%。     

Effect of the feeding rate on microstructure and properties of plasma spheroidized GH4169 powder

The growing interest in additive manufacturing of GH4169 alloy was accompanied by the demand on spherical GH4169 powders with high performance.The powder particles were treated by radio frequency plasma with the different feeding rates.The microstructure and morphology,the particle size distribution of as-treated powders were studied by scanning electron microscopy and laser particle size analysis.It was demonstrated that GH4169 powders with extremely fine followability were obtained by radio frequency plasma spheroidization technology.With the same plasma parameters,the spheroidization efficiency of the particles varied with the feeding rates.When the rate of the powder feeding rates was too small,the excessive absorption of the heating by the powders caused vaporization,then the collection decreased.When the feeding rates was too large,the powder particles were insufficiently absorbed,resulting in defects in the powders.The microstructure of the as-treated spherical particles was mainly cell crystals,columnar crystals,and even microcrystals.Under the suitable plasma parameters,the resulting powders haved a slightly increased average particle size,excellent spheroidization,surface smoothness,followability,and bulk ratio.     

W-Ni-Fe三元合金等离子球化过程的SPH仿真研究

针对表面张力影响下的W-Ni-Fe三元合金,通过光滑粒子流体动力学(SPH)建立了仿真多元金属液滴碰撞融合过程的数值模型,获得了流体在等离子球化过程中的流场和温度分布。结果表明,W的占比越高、粒径越小、环境温度越高、Marangoni力越大,则球化度越好。根据SPH模拟结果选择了平均粒径1.5μm的W粉、平均粒径4.1μm的Ni粉和平均粒径2.4μm的Fe粉为原料,按照质量比W∶Ni∶Fe=90∶7∶3进行喷雾造粒,在等离子焰流温度为8000℃条件下球化,球化后的三元合金粉末球形度好,内部致密。球化后颗粒流动性为11.62 s/50 g,松装密度10.66 g/cm3,有利于使用铺粉方法进行3D打印。证实了SPH仿真结果可靠,该模拟结果可用于指导难熔金属W的等离子球化制备工艺。     

钽粉等离子体球化及其球化过程中卫星粉的形成机制

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。     

Spheroidization of a granulated molybdenum powder by radio frequency inductively coupled plasma

To reduce mass loss and improve spheroidization efficiency during the spheroidization process, a granulated molybdenum powder was spheroidized by radio frequency induction plasma. The influences of plasma power and addition of hydrogen in the sheath gas on spheroidization were investigated. Results show that spheroidization is improved with the increase of plasma power. The best spheroidization can be achieved when the plasma power is 43 kW. Spheroidization percentage, Hall flow time and apparent density of powders spheroidized at 43 kW are 99.8%, 12.5 s/50 g and 5.52 g/cm³, respectively. The addition of hydrogen in the sheath gas can also improve spheroidization. Moreover, investigation of typical morphologies during spheroidization of the individual granulates indicates that the spheroidization process is a combination of melting, sintering and solidification.     

Properties evolution of additive manufacture used tungsten powders prepared by radio frequency induction plasma

In this study, radio frequency induction plasma was adopted to improve tungsten powder properties to meet the requirements of additive manufacturing process. After plasma spheroidization process operated, tungsten particles changed from irregular shape to uniform spherical shape. The average size and oxygen content of raw tungsten powders were both decreased, meanwhile, the laser absorption coefficient was increased by plasma spheroidization process. Furthermore, a series of tests were carried out for raw and spherical tungsten powders to investigate the influence of plasma spheroidization process on powder flowability evolution. The results displayed that, plasma spheroidized powders had a better comprehensive flowability, such as basic flow property, aerated flow property, compressibility, permeability and shear property, comparing to raw tungsten powders. In conclusion, plasma spheroidized tungsten powders met demands of additive manufacturing process very well.     

喷雾造粒预合金化W-Ni-Fe三元合金粉末及射频热等离子体致密球化研究

球形致密化的钨基（W-Ni-Fe）合金粉末对增材制造等粉末成形构件的强度等物理性能的提升具有重要意义。采用喷雾造粒和射频热等离子体高温致密球化处理的方式研究了W-Ni-Fe粉末经喷雾造粒后射频热等离子体处理对其合金粉末的形貌、孔隙等的作用效果。研究表明,经喷雾造粒后所形成的96W-2.5Ni-1.5Fe三元合金粉末显微组织结构疏松,内部中空洞较多且表面粗糙;射频热等离子体对喷雾造粒粉进行处理后其综合性能提高,球形粉表面孔洞及疏松现象有所缓解,但仍有部分颗粒表面与内部存在微孔,且致密球化后的W晶粒之间Ni、Fe相含有较高含量的W元素。     

感应等离子体球化热喷涂粉体材料研究进展

介绍了传统非等离子体法制备球形粉体方法--雾化法和喷雾造粒法,分析了其在热喷涂球形粉体制备过程中存在的优势和局限性。综述了等离子球化技术在热喷涂粉体材料领域中的应用现状,并深入讨论了感应等离子体球化过程中不同的工艺条件对粉体球化率和形貌的影响:原料粉体状态决定了球化后粉体的平均粒径,降低粉体原始粒径可以提高熔融程度,粒径分布较窄的原始粉体有利于得到高球形度粉体;适当增大输入功率和工作气体流量,可降低细小颗粒的粘附现象;工作气体的种类会影响等离子焰炬的热焓值;送粉速率需要结合粉体性质择优选取。这些关键影响因素对热喷涂粉体性能的调控机制,以及深入认识等离子体作用条件下的热喷涂粉体球化机理,提供了有力的理论支撑。总结和展望了感应等离子球化技术在热喷涂陶瓷粉体材料制备中存在的问题和发展方向,感应等离子体球化技术作为制备高纯度、无污染热喷涂球形粉体材料的一种新技术,具有广阔的应用前景。     

Thermal Plasma Spheroidization of High-Nitrogen Stainless Steel Powder Alloys Synthesized by Mechanical Alloying

This paper presents the results of experimental studies on the treatment of Fe–23Cr–11Mn–1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a thermal plasma. Fe–23Cr–11Mn–1N high-nitrogen stainless steel powder alloys were prepared by MA in the attritor under an argon atmosphere. For spheroidization of Fe–23Cr–11Mn–1N high-nitrogen stainless steel powder alloys, the TekSphero 15 plant manufactured by Tekna Plasma Systems Inc was used. The studies have shown the possibility of obtaining Fe–23Cr–11Mn–1N high-nitrogen spherical powders steel alloys from the powder obtained by MA. According to the results of a series of experiments, it was found that the results of plasma spheroidization of powders essentially depend on the size of the fraction due to some difference in the particle shape and flowability, and on the gas regime of the plasma torch. It is established that during the plasma spheroidization process, some of the nitrogen leaves the alloy. The loss rate of nitrogen depends on the size of the initial particles.