7055铝合金粉末的氩气低压雾化技术

将传统环缝喷嘴结构改造为Laval型出气口,以实现低压高效雾化制粉,利用该喷嘴进行7055铝合金氩气低压雾化制粉实验,对Laval型喷嘴的雾化能力、熔滴凝固特性与粉末微观组织进行研究。结果表明：与传统紧耦合喷嘴相比,Laval 型喷嘴具有更好的低压雾化能力,在较低雾化压力下即可获得超音速雾化气流,雾化压力为0.4,0.6和0.8 MPa时雾化粉末的质量中径d50分别为63.5,57.1和43.4μm,大部分合金粉末呈球形或类球形;雾化熔滴凝固过程中产生大量尺寸在0.5~2.5μm范围内的细小枝晶组织,枝晶间距λ与粉末粒径d近似满足如下关系：λ=0.1923 d 0.547;雾化粉末具有快速凝固特性,冷却速率达到104~105 K/s,随熔滴粒径增大而减小。     

经济的热压雾化技术

在气体雾化液态金属时，加热的气流可使其更加有力。如果所有其他的雾化参数保持不变，加热气流可降低粉末平均粒度。它适于生产金属注射成形用廉价粉末。316不锈钢粉的雾化试验表明，热气雾化比冷气雾化可提高金属注射成形用粉的收得率约40％。其原理是，雾化用超声气体喷嘴的气体出口速度随雾化驻点温度的升高而显著增大。     

连续铸钢气水喷嘴特性的研究

本文阐述了连续铸钢气水喷嘴的结构型式及其在设计中的主要技术要求。从理论上分析了雾化介质的压力与被雾化的水的粒径关系;提出了设计气水喷嘴时。选择压缩空气与水的合理压力范围.在导出气水喷雾冷却条件下传热数学模型的基础上对传热问题进行了初步探讨,并对气水喷雾冷却节水的原因进行了简要分析。     

莱钢集团粉末冶金有限公司4万t/a水雾化钢铁粉末生产线建成投产

20 0 3年 8月 30日 ,我国目前规模最大的 4万t/a水雾化钢铁粉生产线在山东莱钢建成投产 ,来自全国各地的专家、学者及业内人士代表 2 0 0余人出席了投产庆祝大会并参观了该生产线。该生产线完全采用自主技术建成 ,解决了多项水雾化钢铁粉末规模化生产的技术难题 ,并取得了 3项发明专利和 7项实用新型专利 ;采用了多项先进技术和装备 (其中喷嘴的雾化量级达到 4 0 0kg/min以上 ) ,使水雾化钢铁粉末产品质量达到国际同类产品先进水平。该生产线的建成投产将极大的缓解我国高性能钢铁粉末供应紧张的局面莱钢集团粉末冶金有限公司4万t/a水雾化钢…     

金属注射成形用水雾化不锈钢粉末的制备与应用

通过设计水雾化喷嘴结构,优化冶炼工艺,采用水-粉离心分离方法,批量生产出适合MIM使用的不锈钢粉末,并制备了不锈钢粉末的MIM样品,与国外同类产品作了对比评价.结果表明,改进的水雾化工艺制备的不锈钢粉末粒度细,氧含量低,振实密度高,性能已达到国际同类产品先进水平.     

除尘系统双流量喷嘴的性能试验研究

通过试验研究了除尘系统双流量喷嘴，在喷嘴不同结构参数下气压和水流量变化的特性，分析了喷嘴结构参数、气压、水流量对水压、气耗率、雾化角、颗粒度以及水滴喷出速度的影响规律，优化后的喷嘴有效地改善了烟气冷却不充分的状况。为喷嘴雾化冷却性能的分析研究和优化设计提供了技术途径。     

一种新型气水雾化冷却喷嘴

CY型气水雾化冷却喷嘴是为不锈钢连铸二次冷却研制的一种新型预混合雾化型扁平喷嘴。该喷嘴的雾化原理和一般气水雾化喷嘴不同,具有雾化质量高、气耗低的特点。笔者提出统一定义喷嘴技术性能的必要性。并提出了某些定义,供同行们参考。     

超声波雾化喷嘴的设计

在超声波雾化设计原理的基础上，将雾化喷嘴按照用途进行了分类，总结了三类超声渡雾化喷嘴。在研究雾化汽油等燃料类的喷嘴、雾化水类的喷嘴的基础上。着重叙述了制取微细金属粉末的超声波雾化喷嘴；在固体雾化技术研究的基础上。研制成一种新型的雾化喷嘴——双层固体技术雾化喷嘴，叙述了它的工作原理和雾化机理，并进行了简单的实验验证。     

模拟分析冷却热轧钢板雾化喷射角度的影响

利用有限元耦合场数值模拟计算方法对雾化冷却热轧钢板进行了模拟,在固定喷嘴到热轧钢板距离H的情况下,得出喷嘴喷射角度对雾化冷却热轧钢板的影响规律,并对重力作用对雾化冷却的影响进行了研究.     

雾化喷射角度对热轧钢板冷却影响的模拟分析

利用有限元耦合场数值模拟计算方法对热轧钢板雾化冷却进行模拟,在固定喷嘴到热轧钢板距离H的情况下,得出喷嘴喷射角度对热轧钢板雾化冷却的影响,并对在有重力作用下的雾化冷却影响进行了分析研究.     

铁锰无磁合金粉的水雾化法生产工艺研究

采用水雾化法制备铁锰无磁合金粉末, 分析了合金粉末含锰质量分数和雾化工艺对铁锰合金粉末性能的影响规律。结果表明: 水雾化法生产铁锰无磁合金粉的方案可行, 但锰质量分数不宜低于24%;在实验工况条件下, 雾化压力对松装密度的影响可以忽略不计, 雾化压力提高使产品流动性变差, 以15 MPa雾化压力进行生产时, 产品工艺性能(松装密度、流动性) 最好; 雾化压力的提高有助于提高产品烧结密度, 在满足产品流动性要求的前提下, 可以考虑通过提高雾化压力来提高产品烧结密度。     

Influence of gas flow on performance of “Confined” atomization nozzles

Supersonic gas jets in “confined” nozzles were studied by Schlieren photography in blank atomizing tests (i.e., no liquid present). Tests in nitrogen at 1.56 MPa pressure showed that changes in the geometry of a nozzle altered the wave pattern and the height of the supersonic region in the jet. In particular, the protrusion height of the metal delivery tube (above the gas exit) had a profound influence. An expansion wave formed at the tip of the nozzle when the protrusion height was too high, and the jet became subsonic in a short distance. Longer supersonic wave patterns were observed at lower protrusion heights following the appearance of a shock wave at the tip of the nozzle. These results correlated well with the atomizing performance of the same nozzles determined previously. The nozzles which had long supersonic flow regions corresponded to those which produced fine powders, and short supersonic regions were associated with reduced efficiency in performance. This indicated that the preservation of high velocities in the gas was of primary importance for effective liquid breakup in atomization. A procedure (based on the characteristics solution of supersonic flow) was developed for assessing flow conditions in atomizing nozzles and for calculating the optimum height of the delivery tube for a given geometry to obtain the longest supersonic jet.     

Y型喷嘴运行临界点的冷态实验研究

Y型油喷嘴由于采用介质雾化,喷嘴内存在两种介质两相流动的相互影响。在一定的雾化介质压力下,运行油流量受油、气压差及喷嘴结构影响,在某种情况下会发生喷嘴运行油流量为零,雾化气倒流入油管的临界工况。对一种结构的三个Y型喷嘴进行了流量特性实验,并采用冷态流量实验图与数据回归关系式计算的方法,确定其临界工况点的运行参数,为喷嘴的可靠运行提供依据。     

Influence of Gas Atomization Parameters of the KhN60M Alloy on the Powder Characteristics for Laser Surfacing

Powders of the KhN60M alloy (EP367, 06Kh15N60M1) are investigated. An overview of manufacturing methods of products of the KhN60M alloy is presented with the analysis of their advantages and disadvantages. It is shown that, when compared with the casting technology and hot pressing of powders of high-alloyed special steels and alloys, additive technologies enable fabricating complexly shaped products with a high level of physicomechanical properties and material utilization factor. The low casting properties of the alloy under study are the reason for the research into atomization to meet the requirements for size, shape, morphology, and fluidity of powders for additive technologies. The goal of this work is to study the influence of the argon pressure during gas atomization on the physical, chemical, and process properties of powders for laser surfacing formed from the KhN60M alloy. The gas atomization technology of the liquid melt by argon using a VIGA 2B laboratory atomizer was used to fabricate the metallic powder of the KhN60M brand at 1560°C and varying the atomizing gas pressure in a range of 22–25 mbar. To select the atomization parameters, the values of the melt viscosity are calculated using the ProCast system for the computer simulation of casting processes by the finite element method and the temperature dependence of viscosity is constructed. The shape and size of the particles and their granulometric composition are studied using laser sedimentation and electron and optical microscopy. The quantitative metallography data are processed using the VideoTest 4 software. The fluidity of powders is measured. It is established that the fraction of spherical particles increases and fluidity of powders improves with an increase in the atomizing gas pressure; the Feret diameter, average particle size, and d₅₀ values vary insignificantly. An experimental dependence of an increase in the yield of the target fraction powder (40–60 μm) with a decrease in the atomizing gas supply is found. The inversely proportional dependence of the fraction of spherical particles on the desired cut fraction is established. The results of the study make it possible to predict the output parameters of powders when atomizing KhN60M steel. Characteristics of powders of the fraction –80 + 40 μm with a shape factor of 0.99 and fluidity of 14–15 g/s make it possible to use them for manufacturing products using additive technologies.

     

Conditions of preparation and properties of atomized iron and iron-alloy powders

Conclusions The results are presented of an investigation into the influence of melting technique, melt composition, and the atomizing medium on the fabricating and physical properties of powders with spherical, compact particles. Characteristic features of the disintegration of metallic melts and of the shaping and oxidation of particles in the air and nitrogen atomization of the melt stream are examined. The desirability is demonstrated of deoxidizing metals and alloys by diffusion in the melting process and employing inert atomizing media to obtain oxide free powders of ferromagnetic metals and alloys. On the basis of this investigation, recommendations are given for the production of high quality ferromagnetic powders for use in electrical apparatus.Translated from Poroshkovaya Metallurgiya, No. 11(71),pp. 1–7, November, 1968.     

雾化铜粉制备技术的研究进展

本文概述了雾化法制备铜粉的研究进展,阐述了雾化法制备铜粉各工序的基本原理,探讨了雾化介质、氧化还原、还原、雾化方式、熔炼、破碎球磨等工序的技术特点,提出了更加合理的低松装密度雾化铜粉的生产工艺流程.     

3D打印用金属粉末的性能特征及研究进展

3D打印(增材制造)作为区别于传统去除型加工的新型制造技术,正以其简易的制造工艺、较低的生产成本和较短的研发周期,备受人们关注。目前,3D打印技术已经开始从研发阶段逐步向产业化发展,但是3D打印用金属粉末的成本及其性能成为制约该产业快速健康发展的瓶颈之一。3D打印用金属粉末需要满足高纯度、高球形度、细粒径和窄的粒径分布等要求。其制备方法主要有雾化法、等离子体法、旋转电极法、等离子熔丝法等。通过3D打印用金属粉末性能要求、制备方法、粉末性能对3D打印零件的成形效果影响等几个方面介绍国内外的一些研究进展,并提出目前3D打印用金属粉末制备所面临的问题。     

Beneficial effects of nitrogen atomization on an austenitic stainless steel

Fully dense nitrogenated austenitic stainless steels were produced by gas atomization and HIP consolidation. The base alloy, 304L, contained about 0.15 wt pct nitrogen when melted under a nitrogen atmosphere, and a modified version of 304L with 23 wt pct Cr contained 0.21 wt pct nitrogen. A series of experiments using various combinations of N₂ and Ar as the melt chamber backfill gas and atomizing gas demonstrated that the nitrogen content of the powder was largely controlled by the backfill gas and that the fraction of hollow particles was determined by the atomization gas. The hollow powder particles, which are common in inert-gas atomized materials, were virtually eliminated in the nitrogen atomized powders. Additional atomizing experiments using copper and a nickel-base superalloy indicate that low gas solubility in the metal leads to gas entrapment. Hardness and compression behavior (yield strength and flow stress) are substantially improved with the addition of nitrogen. The results of this study suggest that the properties of nitrogenated stainless steels fabricated in this manner are comparable to other high nitrogen austenitic alloys. G.M. JANOWSKI, formerly NRC/NIST Postdoctoral Research Associate, National Institute of Standards and Technology.     

若干雾化参数的理论简析

本文就Ａｌ－Ｆｅ系高温铝合金快速凝固雾化制粉过程中若干雾化参数从理论上作了分析。