Separation of inclusions from liquid metal contained in a triangle/square pipe by travelling magnetic field

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Separation of inclusions from aluminum melt using alternating electromagnetic field

Effects of processing variables such as frequency of imposed magnetic field, imposed magnetic flux density, processing time, diameter of inclusions, and value of r1/δ on the electromagnetic separating(EMS) removal efficiency were analyzed theoretically. The higher the frequency, the wider the range of r1/δ will be. Removal efficiency reaches the maximum while r1/δ ranges from 1.5 to 2. And the experimental results on aluminum melt show that higher frequency and magnetic flux density make for higher removal efficiency, matching well with the theoretical results. When f is 15.6kHz, Be is 0.1T, and imposed time is 10s, more than 80% inclusion particles with 6μm diameter can be removed.     

焊缝金属氧化物夹杂的尺寸及分布辅助外电场控制法

提出了一种在埋弧自动焊熔渣-熔池间随焊施加一辅助外电场,利用外电场控制熔体内部离子流进而控制焊缝氧化物夹杂尺寸及其分布的方法,并以直流电源提供的电压作为外电场开展了初步试验研究.结果表明,以钨材作外电场的阴极向液态熔渣内部补充大量的自由电子可极大地改善液态熔渣的导电性能,有效地诱导熔体内部形成稳定的定向离子流;外电场作用于熔渣-熔池通过使熔体内部复合粒子的进一步电离,正负离子形成互为逆向的离子流并在界面产生电化学反应以减少氧化结合的机会,因而有利于夹杂物的细化及弥散分布;同时外电场也可促使熔池内部自由氧离子电迁移至渣-金界面,并在界面优先与熔渣中氧化物形成元素结合进入熔渣从而削弱熔渣对熔池金属的氧化作用,使焊缝金属的氧含量显著降低.     

铝熔体中夹杂物的电磁分离

根据电磁分离铝熔体中的非金属夹杂物数值模拟结果,设计并制作了电磁感应线圈和分离器。感应线圈的设计参数为长度250mm,长度方向匝数为125匝,高度100mm;高度方向的匝数为2匝,宽度为100mm,宽度方向的匝数为2匝,两线圈距离为40mm。分离器内腔尺寸为80mm×20mm×80mm,分离通道尺寸为37.5m×20mm×80mm。研究了铝熔体温度、时间和线圈电流对分离铝熔体中非金属夹杂物的影响,结果表明,当铝熔体温度为740℃,分离时间为3min以上,线圈通入20A电流时,电磁分离夹杂物的效果较好。     

夹杂物对Ag-Cu-Zn钎料凝固组织和性能的影响

分析了夹杂物对Ag-Cu-Zn基钎料BAg40CuZn(Mn,Ni,Co)组织与性能的影响. 在大气条件下熔炼,BAg40CuZn钎料中的Mn,Co元素易形成Mn₂O₃,Co₃O₄,MnN等夹杂物. 由于氧化物和氮化物的硬度高于BAg40CuZn钎料基体的硬度,且自身的变形能力差,降低了钎料的塑性变形能力. 在塑性加工前期,拉拔力较大,变形过程中产生的挤压力使夹杂物发生碎裂,并沿拉伸变形方向分布. 在塑性加工后期,拉拔力变小,在变形过程中产生的挤压力不足以使夹杂物发生碎裂,造成局部应力增大,当其超过钎料基体的抗拉强度后,在夹杂物周围形成裂纹源并扩展,导致钎料在变形过程中发生断裂.     

Dynamic electromagnetic separation of iron-rich phase inclusions from Al alloy

A lum inum alloy plays a very im portant role in m odern society [1]. As the advancem ent of m odern society, m aterial industry faces the challenge of sustainable developm entand society needs alum inum products ofbetter quality.H oweverthe finalalum inum products always contain certain am ountofinclusions [2] com ing from raw m aterialas wellasproduction process.These inclusionsare usually sm all in size and theirdensities are alm ostthe sam e as thatofthe m etalm elt.Asaresult,itisdifficult…     

Mechanics and forming theory of liquid metal forging

1　INTRODUCTIONIntheliquidmetalforging process ,metalwasdirectlypouredintothediecavity ,thenmechanicalstaticpressurewasappliedbyanoilpresswhichmadetheunsolidifiedandquasi solidifiedmetalflowsolidifywithlittleplasticdeformation .Becauseliquidmetalorquasi solidifiedmetalareeasytoflow ,theprocesscanbecarriedoutwithrelativelylowerconsumptionofdeformationenergy .Comparedwithcasting ,thewayoffeedingwaschanged .Inthesolidificationofliquidmetal,thevolumecontractionwouldresultintheemergenceofthesh…     

Electrical charge of metal oxides in liquid metals

An attempt was made to determine the electrical charging characteristics of metal oxide particles suspended in a liquid metal. A liquid metal and metal oxide particles in the liquid were respectively chosen as a cathode and anode for the potential measurements. By taking a close symmetry of electrical circuit, the potential difference between electrodes could be measured successfully. Experimental results show that alumina carries a positive charge by providing electrons to the liquid metal phase such as molten lead and molten aluminum. The potential difference was in the range of 0.01 and 0.08 mV, and was increased with increasing temperature and the amount of oxide added to the liquid metal. Most metal oxides in liquid metal carry a positive charge owing to the formation of the space-diffused charge layer.     

稀土氧化物及合金元素对堆焊金属显微组织的影响

采用金相显微镜对堆焊金属的显微组织进行了观察,用X射线衍射仪(XRD)对堆焊金属中相结构进行了分析,用扫描电镜(SEM)及能谱仪(EDS)对断口形貌及夹杂物进行了观察分析.结果表明,在含有Cr,Mn,Mo,N i等合金元素的焊条药皮中添加稀土氧化物,其堆焊金属组织为细针状铁素体,断口为细韧窝状,且分布均匀.而未添加稀土氧化物的堆焊金属组织为粗针状铁素体及少量珠光体,断口中存在准解理断裂形貌.添加稀土氧化物后,堆焊金属中夹杂物类型发生改变,形状近似球形,尺寸均在6μm以下,且弥散分布于堆焊金属中.     

液态金属Ga的快速凝固模拟

采用分子动力学方法对液态Ga 的凝固过程进行了模拟研究. 结果表明, 与通常液态及非晶态金属相反, 随着温度降低, 与二十面体相关的1551键型数越来越少, 而与菱面体相关的1311, 1301和1201键型数目显著增加, 最后形成以菱面体结构单元为主的非晶态结构. 以1.69×1012K/s的速度冷却时, 得到非晶态结构; 以1.01×1011K/s的速度冷却时, 发生晶化, 结晶转变温度约为144K.     

交变磁场分离铝熔体中Fe、Si的金属间化合物

根据含Fe、Si杂质和铝熔体的导电性之间的差异．应用电磁场将其从铝熔体中分离出来。测量和分析了自制设备所产生的电磁场。将Mn加入到铝溶液中。把针状和树枝状的金属间化合物颗粒改变为块状和含角状的结晶体。并且在不同的试验条件下，利用电磁场净化预先配制好的合金。试验结果表明，变形后的杂质的分布会随着磁感应强度的改变而变化，加入Mn可以显著提高杂质颗粒的迁移效率。     

Joining of metal bars by a new process of transformation-diffusion brazing

Within the bonded interface of metal bars joint produced by conventional solid state bonding process （ such as flash welding, resistance butt welding, friction welding and so on）, the inclusions are often present, which degrade the ductility of joint. A new process of transformation-diffusion brazing is proposed, in which an amorphous foil containing melting point depressant is preplaced between the interfaces to be joined, and the assembly is repeatedly heated/cooled without holding time at peak temperature. A low carbon steel bars, BNi-2 amorphous foil and resistance butt welding machine were used. The results show that surfuce contamination can be disrupted by the dissolution of base metal into molten interlayer in comparison with conventional process, and the ductility of joint can be improved by increasing the times of temperature cycles on line. In addition, transformation-diffusion brazing can be done with relatively simple and inexpensive system in comparison with transient liquid phase bonding.     

Impurity distribution in distillate of terbium metal during vacuum distillation purification

The distribution rules of impurities in distilled terbium metal were investigated by vacuum distillation purification experiment and theoretical analysis. It is found that Ti impurity in distilled terbium is 220 mg/kg in the initial stage of the distillation purification, increases slowly in the middle stage, and increases rapidly in the last stage, reaching 2260 mg/kg, and the modified separation coefficient of Ti is 1/19.02. The diffusion of the impurity Ti in liquid metal can reach a quasi-equilibrium state in the initial stage of distillation purification and the calculated results agree well with experimental results; the distribution profile of impurity Cu is opposite to Ti, being 380 mg/kg in the initial stage, decreasing linearly to 290 mg/kg in the last stage, and the modified separation coefficient is 17.99, and the theoretical calculated results are inconsistent with the experimental result.     

Predictive association of metal–organic systems in the solid-state: the molecular electrostatic potential based approach

Designing crystalline solids with improved properties or performances remains a challenging task, despite great strides that have been made within the field of crystal engineering since its birth several decades ago. Herein, we are bringing examples that illustrate recent successes in taking supramolecular synthetic guidelines from the organic crystal engineering and adjusting those to metal-containing systems, particularly to the lower-dimensional ones. The versatility of calculated molecular electrostatic potential (MEP) as a new crystal engineering tool is demonstrated.     

磁场对双丝间接电弧焊熔滴过渡的影响

对磁场作用下的双丝间接电弧气体保护焊熔滴过渡变化规律进行了研究,通过励磁线圈对间接电弧施加外部横向及纵向磁场,磁感应强度值由特斯拉计侧出,熔滴过渡过程借助于高速摄像系统拍摄,并由示波器同步记录下电流和电压值的变化.研究表明,随正向横向磁场强度增加,熔滴颗粒变细,过渡频率增加,随负向横向磁场强度增加,熔滴颗粒变大,过渡频...     

高效MAG焊接旋转射流过渡时液流束的运动分析

利用高速摄像研究了高效MAG焊接旋转射流过渡过程,对旋转射流过渡过程中液流束以及电弧运动进行了观察.通过分析液流束和焊接电弧上的作用力,揭示了旋转射流过渡时液流束的运动特性以及液流束的运动与焊接电弧的运动之间的主从关系.指出旋转射流过渡时特有的焊接电弧形态所产生的电弧力促使液流束的旋转,而液流束的旋转又带动焊接电弧的旋转.在旋转过程中,液流束上阳极斑点力促进了液流束的旋转,而工件上阴极斑点的粘着性阻碍了电弧的旋转.因此可以通过控制焊接电弧形态,达到控制旋转射流过渡过程的目的.     

金属氧化物半导体纳米晶液相法控制合成研究进展

对金属氧化物纳米晶的晶型、形貌及晶粒大小调控方法进行了综述,重点介绍了液相合成体系中表面活性剂、溶剂、杂质离子等因素对纳米晶形貌、晶型的调控作用以及各种方法的特点,提出发展绿色、高选择性合成方法制备单分散结构可控的金属氧化物半导体纳米晶仍是今后重要的研究方向之一。     

行波磁场净化液态金属的电磁力参数

对影响液态金属所受电磁力大小的因素进行了研究, 对电磁力作用下的导电流体中的非金属颗粒的迁移速度进行了测定。结果表明： 金属液回路的几何尺寸、行波磁场发生器的气隙大小以及发生器中通过的电流等对电磁力参数产生很大的影响; 行波磁场能使微细非金属夹杂物（５ ～１００ μｍ） 的迁移速率成倍提高     

夹杂物对微合金钢熔敷金属针状铁素体形核的影响

研究了微合金钢熔敷金属中夹杂物大小、尺寸分布和化学成分对针状铁素体形核的影响。结果表明,作为针状铁素体形核核心的夹杂物,其尺寸大多数位于0．2．0．6μm之间,并且是含有多种元素的复合夹杂物,具有化学成分不均匀的性质。夹杂物作为一种高能的惰性表面,降低了形核能垒,促进了针状铁素体的形核。当一个针状铁素体以夹杂物为初始核心先期形核后,又可诱发大量的相互交错的针状铁素体感应形核。