增材制造用高流动性铝合金粉末制备技术研究

采用自主开发的旋转盘离心雾化实验装置进行雾化制备增材制造用铝合金粉末实验研究,通过开展雾化盘实验研究优选出粒度分布较均匀收得率较好的盘形,并获得其结构和工艺参数的影响规律;通过对制得的铝合金粉末性能和3D打印成型件物理性能进行检测。结果表明:离心雾化制备的铝合金粉末具有高流动性、窄粒度、高球形度、高松比,表面光洁无卫星粉,无空心粉等特点,同时3D打印离心雾化样件熔覆道均匀,孔洞缺陷少,致密度和力学性能明显优于气雾化样件,尤其是抗拉强度和屈服强达到495和320 MPa,相比气雾化粉打印样件提高近10%。     

改性平面流铸粉末化过程的数值模拟

在传统平面流铸技术的上,研究出一种新的粉末制取技术－－改性平面流铸粉末化技术。将改性平面流铸粉末化工艺过程分为平面液流的形成、平面液流的破碎和金属粉末的形成3个主要阶段,对这3个阶段建立了完整的数学模型,并对Sn60Pb40合金粉末化过程进行了数值计算。计算了平面液流形成过程动态熔潭中熔融金属液的温度场和流场,以及所得金属粉末的尺寸,计算结果与实验结果相吻合。考察了喷嘴几何尺寸、雾化气氛气体密度等主要工艺参数对改性平面流铸粉末化工艺的影响。     

Influence of melt superheat on breakup process of close-coupled gas atomization

In close-coupled gas atomization（CCGA）, the influences of melt superheat on breakup process are fundamental to obtain desired or finer powder. Based on a series of Cu atomization experiment under different superheating conditions, the influences of melt superheat on breakup process were studied. Experimental results indicate that as the melt superheat is increased to 150, 200, 250 and 300 K, the mean particle size （D50） decreases consequently to 34.9, 32.3, 30.9 and 19.7 μm. Theoretical analysis reveals that the primary breakup and secondary breakup processes are close coupled, and the melt superheat radically influences the melt properties, and plays a crucial role on governing the filming process of primary breakup and the atomization modes of secondary breakup. There exists a strong nonlinear decrease of contact angle of melt to nozzle orifice wall when the superheat is increased fi＇om 250 K to 300 K, leading to a marked fall of the film thickness formed in primary breakup, and D50 of copper powders is therefore sharply reduced. However, the log-normal distribution feature of particle size has not been substantially improved.     

基于Laval喷嘴的层流气雾化法工艺参数探索及粉末性能研究

基于Laval喷嘴的层流气雾化技术可以高效制备高性能金属粉末,但目前对这种技术的各项工艺参数及粉末性能尚未有系统性研究。本工作使用基于Laval喷嘴的层流气雾化制粉设备制备了AlSi10Mg合金粉末,同时使用传统分析方法和X射线计算机断层扫描技术分别研究了雾化气体压力以及导流管内径对粉末整体形貌、三维形貌、球形度、粒度分布、物理性能及内部缺陷的影响,并结合数值模拟进行机理性解释。结果表明,基于Laval喷嘴的层流气雾化技术制备的AlSi10Mg粉末性能较好,由于在较高的雾化气体压力和较窄的导流管内径条件下气液流量比更高,金属熔体更易发生破碎,故制备的粉末球形度更好,粒度分布较窄,细粉收得率可接近50%,不规则粉末及空心粉较少。     

Sn60Pb40 solder powders produced by the planar flow casting atomization process

Conventional planar flow casting (PFC) is one of rapid solidification processes for the fabrication of microcrystalline or amorphous ribbons. Based on the conventional PFC process, the planar flow casting atomization (PFCA) process has been developed, which is a new rapid solidification process for the production of metal powder directly from alloy melts. A prototype experimental apparatus was designed and manufactured.With the apparatus, Sn60Pb40 alloy solder powders were prepared, and the effects of the main technological parameters on the powder size distribution and morphology were experimentally studied. The experimental investigations indicate that the metal powders produced by the PFCA process can be classified by velocity; and fine spherical tin-lead alloy solder powders can be fabricated by adjusting the technical parameters. The new PFCA process has such features as high productivity and efficiency, low energy consumption, simple operation,short technological process, and large gross yield.     

快速凝固雾化工艺对铝合金粉末形貌和粒度分布的影响

利用气体雾化法制备铝合金粉末,通过扫描电镜和机械筛分法对金属粉末的表面形貌和粒度分布特点进行了系统地考察.探索出一种较佳的雾化工艺.结果表明,利用气体雾化法制备的粉末,其尺寸及形状不是很均匀,粉体粒度分布呈正态分布.并对各参数影响规律作了比较讨论.     

Cu-20%Co合金雾化液滴的凝固组织特征

对Cu-20%Co合金进行了高压气体雾化快速凝固实验,获得了富Co相以微细球形粒子形式分布于基体的Cu20%Co合金粉末.富Co相粒子的尺寸随着粉末尺寸的增加而增大.在凝固过程中,富Co相液滴受固-液界面推斥;凝固后,Co相粒子主要分布于晶界.由于富Co液相的表面能较高,液-液相变时弥散相液核通常在雾化液滴内部形成,并在温度梯度的作用下向雾化液滴中心迁移,从而导致在粉末表面形成很薄的富Cu基体相层.     

气雾化制备Pd-Ag-Cu粉末钎料的研究

研究了惰性气体雾化法制备Pd-Ag-Cu合金粉末。在喷嘴结构不变的情况下,改变过热度、雾化压力、导流管的内径,导流管伸出长度都会影响到Pd-Ag-Cu合金粉末的粒度与粉末收得率。通过调整各项工艺发参数研究发现,提高过热度和雾化压力,减小导流管内径有利于降低粉末粒度,导流管随着伸出长度的增加,粉末粒度先降低后增加。各项参数都有临界值,不能无限制增大或减小,综合调整才能达到最佳制粉效果。     

两种3D打印用雾化Ti-6Al-4V粉末的对比研究

本研究分别利用水冷铜坩埚真空感应熔炼气雾化(VIGA-CC)和等离子旋转电极(PREP)两种技术制备出球形Ti-6Al-4V合金粉末,作者利用SEM、同步辐射CT扫描-三维重建和氩气含量测试等分析手段对不同粒径的Ti-6Al-4V合金粉末的孔洞缺陷和氩气含量、硬度值进行了表征。实验结果表明, VIGA-CC粉末粒度分布宽,细粉收得率较多,粉末粒度分布在40~180 μm之间, PREP粉末的粒度分布较窄,主要集中在110~180 μm之间；金属粉末内部的孔隙率、气体含量和孔尺寸随着粉末粒度的增大而增大,且同一粒径范围内VIGA-CC粉末的气孔概率多于PREP粉末；随着粉末粒径减小,粉末截面组织逐渐细化,其硬度值逐渐升高,整体上VIGA-CC粉末硬度值高于PREP粉末。     

高压水雾化法制备的高硅铝合金粉末特性

用高压水雾化法制备高硅铝合金粉末．并对粉末的特性进行了分析检测.实验结果表明、用该方法可制得含氧量低、粒度分布均匀、压制性好的合金粉末与同种合金的铸造试样相比,粉末的显微组织得到了显著细化,Si相的形态、尺寸及分布得到了明显改善,其α-Al基体因合金元素固溶度的提高得到了显著强化     

双级雾化快速凝固高硅铝合金粉末形貌及组织特征

采用双级雾化装置制备了四种铝合金粉末，分析了粉末的粒度组成，颗粒形貌和微观组织，计算了粉末的冷却速度，双级雾化粉末的平均粒度比单级气体雾化粉末细两倍，平均冷却速度高一个数量级；Ａｌ－Ｓｉ二元合金中，细小颗粒的微观组织主要由不同Ｓｉ含量的块状过饱和固溶体组成。     

基于同步辐射CT技术表征3D打印用气雾化TC4粉末的研究

本研究利用气雾化技术制备球形TC4合金粉末,作者利用SEM、同步辐射CT扫描-三维重建等分析手段对异常颗粒粉体以及不同粒径的TC4合金粉末表面和内部的孔缺陷进行了表征。实验结果表明,本研究制备的TC4合金粉末随着粉末粒径减小,粉体表面由凸凹不平的冷凝收缩痕迹渐变为光滑表面,粉体内部的孔隙逐渐减少,且孔隙尺寸也随之减小;经分析,由于雾化过程中凝固与球化时间的差异及飞行轨迹的不同等原因导致了包裹式、连体式、椭球形、卫星粉等异常粉末颗粒的生成;同步辐射CT扫描-三维重建表明,粉末内部的孔隙率和孔隙尺寸随着粉末粒度的增大而增大;作者认为通过调整雾化工艺,使金属熔滴在未开始冷却凝固前彻底雾化破碎,从而能有效解决粉末内部孔隙缺陷的问题。     

气雾化镍基高温合金粉体的过冷度和显微组织特征

雾化技术是一种获得微细球形合金粉体的有效方法,其中雾化过程中的过冷度是影响粉体性能的重要因素。本文借助DSC等实验手段,研究了粉体尺寸和冷却速度对粉体过冷度和显微组织的影响,以及粉体尺寸,冷却速度和过冷度直间的关系。结果表明,粉体尺寸和冷却速度越小,粉体冷却时的过冷度越大。同时,较大的过冷度会显著降低粉体中树枝晶的臂间距。另外,粉体尺寸越小,粉体中的胞状晶的比例越高,晶粒的尺寸也显著减小。     

超音速气体离心雾化工艺参数对银稀土合金粉末性能的影响

采用超音速气体离心雾化敲术，研究了不同工艺条件对银稀土合金粉末性能的影响。结果表明：超音速气体离心雾化有效细化了粉末和显微组织，实现了粉末组织的均匀化；在合适的液流直径下，随着雾化压力、过热温度的增加，银稀土合金粉末粒径更细，但其颗粒形貌变得，更加不规则。     

适用于金属增材制造的球形粉体制备技术

金属增材制造技术作为一项革命性的先进制造技术,从20世纪90年代兴起并得到迅速发展,受到各国家的高度关注。原料是影响和制约增材制造零部件性能的关键因素之一。球形粉体由于具有良好的流动性和铺展性、以及较高的松装密度与压实密度等优异性能,是金属增材制造的理想原材料。本文针对球形粉体的雾化制备技术以及粉体的球化技术,详细总结了雾化和球化技术的相关原理、方法和技术特点,并针对金属增材制造对球形粉体制备技术的发展进行了展望。     

气雾化制备金属粉末的研究进展及展望

金属粉末作为增材制造的关键原材料,其品质很大程度上决定了产品最终质量.气雾化制粉技术所制备的粉末具有粒度细小、球形度高、氧含量低等优点,已成为增材制造高性能金属构件的主要原材料.本文综述了气雾化制粉技术的基本原理与特点,总结了近年来气雾化制粉用喷嘴结构类型、气体流场结构与仿真模拟、粉末质量调控及工艺参数控制等方面的研究...     

过共晶铝硅合金的制备与性能研究

采用水雾化法制备了Al-20Si-0.35Re过共晶铝硅合金粉末,对合金粉末进行了热压烧结,测试了导电率和显微硬度随热压压强的变化。结果表明：采用水雾法可制得含氧量低、粒度分布较好的合金粉末,热压后的块体样品导电率和显微硬度均随着热压压强的增大而提高。     

平面流铸雾化制取锡铅合金粉末的研究

传统平面流铸技术是用于生产微晶或非晶合金薄带的一种快速凝固技术。在传统平面流铸技术的基础上,开发出一种新型的快速凝固制粉技术—平面流铸粉末制备技术。自行设计制造了平面流铸粉末制备工艺试验装置,用此工艺装置制取了锡铅合金粉末,试验分析了制粉工艺参数对所制取锡铅合金粉末的尺寸分布和形貌的影响规律。大量工艺试验表明,平面流铸制粉工艺能对所制取的锡铅合金粉末进行速度分级。     

Characterization of spherical AlSi10Mg powder produced by double-nozzle gas atomization using different parameters

A self-developed double-nozzle gas atomization technique was used to produce AlSi10Mg powder. Effects of delivery tube diameter, gas pressure, and melt superheat on powder characteristics were investigated. The concepts of bluntness and outgrowth were introduced to analyze powder sphericity and satellite index quantitatively. The results showed that the median diameters of all atomized powders ranged from 25 to 33 µm. The highest yield rate (72.13%) of fine powder (<50 μm) was obtained at a superheat of 350 K. The powder size decreased with increasing melt superheat but increased with increasing delivery tube diameter. Powders with bluntness values between 96% and 98% accounted for over 60%. The outgrowth values demonstrated that 70%?85% of all powders did not contain satellite particles, with few powders adhered two or three particles. Not only Al and Si phases were present but also a metastable Al₉Si phase was detected.     

High pressure EIGA preparation and 3D printing capability of Ti—6Al—4V powder

Ti—6Al—4V alloy powder was processed by electrode induction melting gas atomization (EIGA) at high gas pressure (5.5–7.0 MPa). The effects of atomizing gas pressure on the powder characteristics and the microstructure, along with the mechanical properties of the as-fabricated block by laser melting deposition (LMD), were investigated. The results indicate that the diameters of powders are distributed in a wide range of sizes from 1 to 400 μm, and the median powder size (d₅₀) decreases with increasing gas pressure. The powders with a size fraction of 100–150 μm obtained at gas pressures of 6.0 and 6.5 MPa have better flowability. The oxygen content is consistent with the change trend of gas pressure within a low range of 0.06%–0.20%. Specimens fabricated by LMD are mainly composed of α+β grains with a fine lamellar Widmanstatten structures and have the ultimate tensile strength (UTS) and yield strength of approximately 1100 and 1000 MPa, respectively. Furthermore, the atomized powders have a favorable 3D printing capability, and the mechanical properties of Ti—6Al—4V alloys manufactured by LMD typically exceed those of their cast or wrought counterparts.