Influence of shielding gas on the transfer behavior of droplets

High-speed photography is utilized to capture an image of the arc area during the welding process.The variation in arc shape and droplet transfer behavior is compared when employing shielding gases of different components and proportions(e.g.,80％Ar+20％CO2,85％Ar+10％CO2+5％O2,65％Ar+26.5％He+8％CO2+0.5％O2)using a φ1.2 mm welding wire under 360 A current.Furthermore,the effects of various shielding gas components on the stability of the welding process are discussed.It was determined that the addition of oxygen and helium changed the arc's shape and the behavior of the droplet transfer,and the welding process stability increased.     

电场作用下金属液滴在电解质溶液中的运动研究

探讨了在电解质溶液中外加可变电场对金属液滴运动规律的影响。使用汞液滴作为研究对象,当汞液滴在含有溴化钾的甘油溶液中保持稳定运动状态时,外加(电压)可调电场,观察不同电压下液滴在溶液中的运动形式及状态。结果表明,改变电场可以控制电解质溶液中汞液滴的运动规律。     

Study of Penetration Depth and Droplet Behavior in the Case of a Gas Jet Impinging on the Surface of Molten Metal using Liquid Ga–In–Sn

To study the penetration depth in the case of a gas jet impinging on the surface of liquid steel, cold model experiments were carried out using a liquid alloy Ga–In–Sn, which had similar physical properties as liquid steel. A HCl solution was used to simulate the top slag. The top phase was found to have appreciable effect on the penetration depth. Comparison of the experimental data with the predictions of the existing models indicated that most the model predictions deviated from the experimental results at higher lance heights and gas flow rates. New model parameter was suggested based on the present experimental data. The observation of the formation and movement of metal droplets generated by the gas jet was also made. The velocity of the droplet was found to be at a level only about 1% of the terminal velocity. This low velocity suggested that the turbulent viscosity played important role and the droplets could have long resident time in the slag.     

高温烟气中水滴非等温蒸发的数值模拟研究

喷雾蒸发冷却技术在钢厂转炉和电炉烟气处理工程中有广泛的应用,对于喷雾蒸发机理的研究是建立在单个水滴蒸发的研究基础之上的。本文依据简化的工况,考虑了水滴内部环流、蒸发过程中的变物性、Stefan流,建立了单水滴蒸发的非等温模型,研究了对流环境下高温气体中水滴的蒸发特性,获得了不同环境温度、水滴初始条件下水滴半径和温度等参数的变化规律。研究发现,水滴的蒸发过程存在快速加热和稳态蒸发两个阶段;初始直径对瞬态阶段的影响较大,而对稳态阶段影响不大;水滴越大,滑移速度对蒸发的影响也越大。对喷雾水滴蒸发特性的数值模拟,为进一步研究液滴群在高温烟气中的蒸发提供了更可靠的方法。     

高温烟气中水滴非等温蒸发的数值模拟研究

喷雾蒸发冷却技术在钢厂转炉和电炉烟气处理工程中有广泛的应用,对于喷雾蒸发机理的研究是建立在单个水滴蒸发的研究基础之上的.本文依据简化的工况,考虑了水滴内部环流、蒸发过程中的变物性、Stefan流,建立了单水滴蒸发的非等温模型,研究了对流环境下高温气体中水滴的蒸发特性,获得了不同环境温度、水滴初始条件下水滴半径和温度等参...     

高温烟气中水滴非等温蒸发的数值模拟研究

喷雾蒸发冷却技术在钢厂转炉和电炉烟气处理工程中有广泛的应用,对于喷雾蒸发机理的研究是建立在单个水滴蒸发的研究基础之上的.本文依据简化的工况,考虑了水滴内部环流、蒸发过程中的变物性、Stefan流,建立了单水滴蒸发的非等温模型,研究了对流环境下高温气体中水滴的蒸发特性,获得了不同环境温度、水滴初始条件下水滴半径和温度等参...     

烧结矿MgO含量对含钒钛炉料熔滴性能影响

利用高温熔滴炉模拟实际高炉软熔带的运行情况.探讨在承钢炉现有炉料结构条件下,炉料中不同Mg O含量对含钒钛高炉炉料软化温度、熔化温度、最大压差、熔滴综合指标等高温物理性能的影响.结果表明：Mg O质量分数由1.92％增加到2.40％后,炉料的软化温度无明显变化;炉料的滴落温度td 升高,熔化温度区间Δtds增大;炉料的最大压差ΔPmax升高,炉料透气性变差;炉料熔滴的总特性值S增大,熔滴性能变差.     

Segregation of C and P in Steel Droplets Solidified in Drop Tube

The properties of steels can be improved by adding appropriate amount of alloying elements.However,the quality and properties of steels may be affected due to the segregation of the alloying elements.Rapid solidification was regarded to be an effective method to reduce or eliminate the segregation of alloying elements.While in this paper,the segregation of C and P was also observed in rapid solidified carbon steel droplets (in silicon oil) by drop tube processing.The distributions of alloying elements in 0.2m drop tube samples were similar to those in 50m drop tube samples.While in both 0.2m and 50m drop tube,the segregation of C and P was quite different when the contents of the samples were varied,the segregation profiles were discussed in detail.The microstructures of 50m droplet samples were a little finer than those of 0.2m droplet samples.The solidification speed was approximately the same from the surface to the center of each sample.In high-C samples,the microstructure was also corresponding to the distribution of C.     

气泡和液滴的碰撞和聚合现象

采用水模型实验和高速摄像技术模拟了钢液中气泡与液滴碰撞聚合的现象和机理。根据韦伯数We和碰撞参数B的关系,气泡和液滴的碰撞结果分为聚合、反弹和拉伸分离3种。聚合分为靠近碰撞、形成液膜、形成稳定接触面、滑移、稳定上浮等过程;反弹分为靠近碰撞、形成液膜、滑移分离等过程;拉伸分离分为靠近碰撞、形成液膜、形成接触面和共同体、形成颈部、断裂等过程。当We很小时,气泡和液滴会发生聚合。随着We的增大,B适中时,两者聚合;B过小,两者反弹;B过大,两者拉伸分离。在实验的We范围内,3种结果中聚合情况最多。由此,根据相似性可以解释在钢液中少见液滴夹杂物的原因。     

Metal Spray Forming Process Examined Using Mathematical Model

The metal spray forming process was examined using the mathematical model simulation by Baosteel＇s test and developed facilities.The mathematical model comprised of the probability and statistical analysis of the droplet mass behavior and predicted the shape and temperature distribution of the billet during the spray forming process.     

单滴沥青燃料燃烧特性的初步研究

本文对涸青单滴的燃烧进行了初步的实验研究，观察的实验现象和测量的结果表明沥青的燃烧具有一些既不同于液体燃料，也与固体燃料不同的特点，表现在单滴温度在着时刻会产生明显的突跃，存在明显的固体残炭的燃烧阶段，单滴体积会明显膨胀等。     

Cu-Mn合金熔体在金属W板上的润湿性

采用高温座滴法测量了温度为1 150℃、真空条件下Cu-Mn合金在W板上的接触角,研究了不同Mn含量对Cu-Mn合金与W板间润湿性的影响并阐述其影响机理.结果表明,随着Mn元素含量的增加,Cu-Mn合金与钨板间的接触角不断减小.分别利用EDS和XRD对座滴合金与W基板间的润湿界面进行了分析,发现Mn元素在界面处产生了富集,富集层厚度为1～2μm;Cu-Mn/W界面处没有新反应物生成;Mn元素的存在促进了界面处Cu、Mn和W间的相互扩散;Mn富集层的存在改善了二者之间润湿性,使Cu/W界面结合方式由最初的机械结合转变为冶金结合,有利于提高二者间的界面结合强度.     

高温熔体雾化过程中过热度的数值模拟

基于紧耦合气雾化喷嘴,运用Fluent软件对高温熔体雾化过程进行数值模拟,分析过热度对高温熔体雾化液滴凝固前飞行距离和液滴破碎程度的影响。结果表明,当过热度增大时,液滴的平均直径(SMD)有减小的趋势,有利于细化雾化颗粒的粒径;液滴的凝固前飞行距离相对比较平缓,中间有小幅的升高趋势。当过热度达到100℃时,液滴的破碎比较充分,颗粒的平均直径满足生产的要求,熔体进行雾化后,其平均直径为52.886μm,液滴的飞行距离为32.68mm。     

高 炉 内 的 液 体 流 动 现 象

 高炉内液体流动现象的研究对控制高炉工艺过程具有重要意义。介绍了目前可描述高炉内液体流动规律各模型的内容、局限性和在高炉工艺上的应用特点。通过对比可知,在填充床层区域大小尺度上,笔者前期建立的模型更全面地描述了填充床层对运动液体的作用。并以此认识为基础,给出了确定该模型参数的实验方法。另外,在填充颗粒大小尺度上,给出了计算机模拟床层内非润湿液流分布的做法,进而据此给出了该模型参数的预测方法。     

宣钢高炉合理炉料结构熔滴试验

 对宣钢12种含钛高炉炉料的化学成分及熔滴性能测试结果进行综合分析,给出宣钢2号高炉（2 500 m3）、3号高炉（2 000 m3）、4号高炉（1 800 m3）不同原料条件下最佳的炉料结构,并对3组炉料结构进行比较。分析认为,2号高炉熔滴性能最好的炉料结构为4号方案,[S]值最小为322 kPa·℃,3号高炉熔滴性能最好的炉料结构为5号方案,[S]值最小为786 kPa·℃,4号高炉熔滴性能最好的炉料结构为11号方案,[S]值最小为790 kPa·℃;3号、4号高炉使用的炉料碱度与2号高炉相比较高,这是造成3号、4号高炉炉料最大压差[（Δpmax）]值高的主要原因;2号高炉使用炉料的含铁品位较高,大于57%,且渣中的MgO质量分数较低,因此炉料在软熔滴落带渣量相对较少,渣的流动性较好,熔滴性能优于3号、4号高炉。     

Ultra Fast Cooling of a Hot Steel Plate by Using High Mass Flux Air Atomized Spray

In the current research, the ultra fast cooling (UFC) of a hot stationary AISI‐304 steel plate has been investigated by using air atomized spray at different air and water flow rates. The initial temperature of the plate, before the cooling starts, is kept at 900°C or above. The spray was produced from a full cone internal mixing air atomized spray nozzle at a fixed nozzle to plate distance; and the average spray mass flux was varied from 130 to 370 kg m^?2 s by selecting different combinations of air and water flow rates. The surface heat flux and surface temperature calculations have been performed by using INTEMP software and the calculated results have been validated by comparing with the measured thermocouple data. The heat transfer analysis indicates that the cooling occurs in the transition boiling regime up to surface temperature of 500°C and thereafter it changes to nucleate boiling regime. The superposed flow of air on the hot plate enhances the cooling in the temperature range of 900–500°C by sweeping the partially evaporated droplets from the hot surface. However, due to the high percentage of fine water droplets in the resultant spray produced at higher air flow rates, the maximum cooling rate is achieved at the medium air flow rate of 30 N m³ h^?1. The cooling rate (182°C s^?1) produced by an air atomized spray is found to be in the UFC regime of a 6 mm thick steel plate. The findings of this research can be considered as the basis for the fabrication of cooling system in the run‐out table of a hot strip mill.     

宣钢高炉含铁炉料熔滴性能

对宣钢高炉炉料结构进行了熔滴性能试验研究。单矿的熔滴试验结果表明:宣钢常用的2种烧结矿软化性能较好,但滴落性能较差,1 520℃仍未滴落;3种球团矿中自产球总体熔滴指标最好但软化区间最长(313℃);2种块矿中PB矿开始软化温度最低软熔区间最长,试验中未能滴落。蒙古矿软熔性能较好,但滴落温度高达1 518℃。通过对15种配矿方案进行的熔滴试验,结果表明:降低烧结矿配比,提高PB矿比例可改善炉料的熔滴性能。在试验条件下,配矿方案为"烧结矿68%+球团矿16%+PB矿16%"的炉料结构熔滴性能最佳。     

液滴微萃取-石墨炉原子吸收光谱法测定环境水样中痕量镉

以双硫腙 CCl4作为萃取体系,采用液滴微萃取方式分离富集镉,建立了以液滴微萃取富集石墨炉原子吸收光谱法测定了环境水样中痕量镉的分析方法。考察了不同萃取条件及仪器条件对测定的影响,并对各项实验条件进行优化。结果表明,方法的检出限为0.82×10-2 ng/ mL,线性范围为0.02~0.60 ng/ mL,一般环境水体中的常见共存离子对测定没有影响。方法应用于实际水样中痕量镉的测定,结果与其他方法的测定值相吻合,加标回收率在95.6 %~97.9 %之间。     

微乳液的稳定性及其在制备超细Y2O3中的应用

探讨了CTAB／n—C4H90H／c-C6H12／H2O体系微乳液的稳定性，绘制了该体系的三元和拟三元相图，当CTAB与n—C4H9OH质量比为2：3时有较宽的稳定的W／O微乳液相区，是制备超细Y2O3的理想体系。在该体系稳定区内，通过调整ω，可改变微乳水核半径。Y（NO3）3溶液和草酸溶液在微乳液水核（微反应器）中进行沉淀反应，制备出不同粒径、形貌的超细氧化钇。样品经X射线衍射（XRD）、透射电镜（TEM）表征，结果表明，ω增大，水核半径增大，超细Y2O3的粒径变小，形貌也发生变化。当ω=17时，可制备出粒径为30nm的晶型完好的Y2O3立方晶粒。