Mathematical model of electromagnetic elimination in tubule with high frequency magnetic field

In order to find the ways to improve the elimination efficiency with high frequency magnetic field, a mathematical model of electromagnetic elimination （EME） in the tubule with high frequency magnetic field was set up. The calculated results show that by ignoring the flow of molten metal, when the surface magnetic induction intensity of the metal （B0） is 0.03 T and the diameter of the tubule is 8 mm, the non-metallic inclusions with 30 μm diameter can be wiped offin 7 s from the center of the molten aluminum, whereas the elimination time of the 5 μm non-metallic inclusions is more than 240 s. When B0 is 0.03 T, the diameter of the tubule is 8 mm and elimination time is more than 30 s, the elimination efficiency of 5μm, 10μm and 30 μm non-metallic inclusions is about 60%, 90% and 100%, respectively, the elimination efficiency increases with the decreasing diameter of the tubule. It can be concluded that increasing the magnetic induction intensity or decreasing the diameter of the tubule can decrease the elimination time and improve the elimination efficiency in EME with high frequency magnetic field.     

铜合金中氧化物夹杂的电磁分离

通过向Cu-10Sn合金中加入1%的Cu2O颗粒制备了含有SnxOy合金的材料,随后利用高频磁场的电磁分离技术成功将铜合金中的氧化物夹杂分离到分离器边缘。研究了分离器直径、磁感应强度、分离时间对分离效果的影响。试验结果表明,当分离器直径为12mm,磁感应强度为60mT,分离时间为60s时,氧化物夹杂的分离效果最好。     

Motion behavior of non-metallic particles under high frequency magnetic field

Non-metallic particles, especially alumina, are the main inclusions in aluminum and its alloys. Numerical simulation and the corresponding experiments were carried out to study the motion behavior of alumina particles in commercial pure aluminum under high frequency magnetic field. At the meantime, multi-pipe experiment was also done to discuss the prospect of continuous elimination of non-metallic particles under high frequency magnetic field. It is shown that: 1) results of numerical simulation are in good agreement with the experimental results, which certificates the rationality of the simulation model; 2) when the intensity of high frequency magnetic field is 0.06 T, the 30 μm alumina particles in melt inner could migrate to the edge and be removed within 2 s; 3) multi-pipe elimination of alumina particles under high frequency magnetic field is also effective and has a good prospect in industrial application.     

直流磁场作用下Al-18Si合金的凝固行为

研究了在单独场源－直流磁场作用下,Ａｌ－１８Ｓｉ（质量分数．％）合金定向凝固时形成富Ｓｉ特殊表面的现象;直流磁场力对熔体无搅拌作用,其磁感应强度为０．２４Ｔ左右时,开始出现Ｓｉ的宏观偏析现象,且偏聚层厚度随磁感应强度的增大而增加;探讨了稳恒直流磁场对此合金微观组织形成规律的影响机理。     

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…     

Al-Si合金熔体中磁性杂质颗粒的电磁分离

分析了处于交变磁场中的磁性杂质颗粒的受力情况，比较了由交变磁场和稳恒磁场产生的磁场力。结果表明这两种力的本质相同，可以统一起来，而且磁性杂质颗粒在其驱动下的运动规律也相同。Al-Si合金中的富铁相杂质是弱磁性，电磁力和磁场力都可以促使其运动，电磁分离试验结果表明，当磁感应强度大于145mT时，电磁力起主要作用，杂质颗粒向分离器内侧运动；当磁感应强度小于120mT时，磁场力起主要作用，杂质颗粒向分离器侧面运动，据此可以指导分离器的结构设计。     

Liquid phase separation of Cu-Cr alloys during rapid cooling

1 Introduction Cu-Cr alloys containing 20%- 50%Cr have been widely investigated because they are the most important contact materials used in high voltage vacuum switches. It has been well known that the smaller the Cr particles in Cu-Cr alloys are, the b…     

退火过程中无取向电工钢的晶粒长大行为及磁性能演变

对Fe-3%Si无取向电工钢冷轧板进行不同时间的退火处理,利用光学显微镜、EBSD等研究了退火过程的晶粒长大行为及其对磁性能的影响。结果表明,随着退火时间的增加,退火板中Goss以及γ织构晶粒占比降低,{114}<841>以及{001}<120>织构晶粒占比增大。在退火时间低于20 s时,退火织构以强γ和Goss织构为主。退火时间为60 s时,{001}<120>织构晶粒长大速率急剧增大,平均晶粒尺寸达到约105 μm。退火时间达到240 s时,退火织构以强{001}<120>以及{114}<841>织构为主。退火时间为30～60 s时轧向及横向磁感值迅速增大,60 s时轧向磁感达到最大值1.74 T,120 s时横向磁感达到最大值1.67 T,之后随着退火时间增加而轻微降低,并分别稳定在1.72 T和1.66 T左右。退火板45°方向磁感值先升高后降低,20 s时达到最大值1.67 T。各方向的铁损值均随退火时间的增加而降低,且磁各向异性逐渐减小。     

聚磁盘形状对磁粒研磨加工管件内表面的影响

目的提高磁粒研磨法加工管件内表面的质量及加工效率,探究磁粒研磨法中不同形状的聚磁盘对管件内表面的影响。方法利用Maxwell软件对轴向开槽聚磁盘与不开槽聚磁盘进行磁场强度模拟和磁感应线模拟,分析不同形状的聚磁盘的磁感应强度变化和磁场强度分布。利用磁粒研磨法对工件内表面进行研磨加工,对研磨之后的工件表面粗糙度进行测量,并对微观形貌进行观察。结果在磁粒研磨工具转速为500 r/min、加工时长为15 min的条件下,聚磁盘为未开槽时,表面粗糙度由原始的0.509μm降至0.127μm,表面粗糙度改善率(%ΔRa)为75.04%;当聚磁盘为轴向开槽时,工件表面粗糙度由原始的0.553μm降至0.097μm,工件的表面粗糙度改善率(%ΔRa)为82.45%。结论在相同的加工条件下,当聚磁盘轴向开槽时,相对于轴向不开槽的聚磁盘,磁粒研磨管件内表面的研磨效果更好,表面粗糙度改善率和研磨效率更高。     

磁场对Cu-Pb-La过偏晶合金液-液分离的作用

本实验在Cu-80%Pb过偏晶合金凝固过程中添加稀土元素La,研究不同冷却速度下稀土元素在过偏晶合金凝固制备中的作用,并研究施加磁场对Cu-Pb过偏晶合金液-液分离区凝固组织的影响,探讨了磁场下第二相的迁移和分布规律,为均质偏晶合金制备技术的改进提供参考。结果表明,添加La元素可显著降低Cu-80%Pb凝固组织中的宏观偏析,促进第二相颗粒的均匀分布和细化。较快的冷却速度下添加La元素的作用更加明显,偏析程度显著降低,在此冷速下进一步施加1 T水平方向磁场,Cu-Pb-La合金凝固过程中宏观偏析得到了抑制,富Cu相颗粒弥散,组织分布均匀。     

高铁锌焙砂在高梯度磁场中的元素分布行为(英文)

采用高梯度磁选将难溶铁酸锌从锌焙砂中分离,并利用ICP、XRD、穆斯堡尔、SEM及激光粒度仪分析锌焙砂中的元素组成及物相结构。考察磁感应强度对铁酸锌及杂质元素如钙、硫和铅在磁选过程中的分布行为的影响。结果表明,85%以上的铁酸锌在0.70T的磁感应强度下能分布到精矿中,60%的钙和 40%的硫主要分布在非磁性物相中,并在磁选过程中富集于尾矿中,大部分的铅以超细颗粒均匀分散在锌焙砂中。     

磁极开槽对磁粒研磨加工镍钛合金血管支架管材内壁表面质量的影响

目的 提高镍钛合金血管支架管材内壁的表面质量及磁粒研磨加工效率,研究开槽与不开槽磁极对磁粒研磨加工镍钛合金血管支架管材内壁表面质量的影响.方法 建立了有限元仿真模型,分别模拟了开槽磁极与不开槽磁极的磁感应强度分布情况.结合仿真结果,使用搭建的镍钛合金血管支架管材内壁磁粒研磨加工设备,分别采用开槽磁极和不开槽磁极进行镍钛...     

Ring--Like Solidification Structure Of Mnbi Phase In Bi—Mn Alloy Under A High Magnetic Field

对强磁场作用下Bi-Mn合金分别从全熔态和从固液两相区开始的凝固过程及其组织的实验研究表明，磁场使初生MnBi相在试样外侧呈环状偏聚，其自身生长为棒状，棒的长轴沿磁场方向呈定向规则排列，而试样心部基本无初生MnBi相。在Curie点以上开始进行较慢的凝固时，由片状聚合而成的棒状MnBi具有单晶特征。对以上现象的形成原因进行了分析。     

Variety of solidification structures in Al-2.89%Fe alloy solidified under high magnetic field

考察了冷却速率、磁场强度及高梯度磁场对Al-2.89%Fe(质量分数)过共晶合金中Al3Fe 相形貌及分布规律的影响. 结果表明, 在无磁场条件下, 初生Al3Fe相沉积在试样下部; 施加12 T强磁场后, 初生Al3Fe相所受磁力作用和重力作用相平衡, 在整个试样中均匀分布, 且沿着易磁化方向[121]发生定向排列, 其取向程度不受冷却速率的影响, 但随着磁场强度的增大而加强; 在高梯度磁场中, 初生Al3Fe相所受磁力作用大于重力作用而偏聚在试样的上部, 且多个针状初生Al3Fe相结合在一起, 形成近似星状聚合体. 此外, 对强磁场的作用机理进行了分析和探讨.     

影响铝熔体电磁净化效果因素的分析

从液态金属电磁净化技术的原理出发,在理论上分析了当夹杂物与金属熔体密度接近的情况下,可以利用两者之间的电性能与磁性能的差异来实现夹杂物的分离,达到金属熔体净化的效果。综述了影响电磁分离效率和效果的因素。表明在电磁净化过程中,通电时间越长、磁感应强度越大、管半径与集肤程度比值在1.5~2.0之间、分离管为异型管、夹杂颗粒越大且近于球形,分离效果越理想,分离效率越高。     

直流磁场作用下Al-13.3%Cu合金的熔点变化

采用双电桥法测定Al-13．3％Cu合金在直流磁场下凝固的电阻一温度曲线,通过对曲线的分析,确定了合金在磁场强度为0．06T和0．12T的直流磁场下凝固时的液相线温度和固相线温度,发现直流磁场对Al-13．3％Cu合金的熔点会产生一定的影响,合金的液相线和固相线温度下降,结晶问隔变大,并且当磁场强度为0．12T时这种变化更明显。     

Efficient enrichment of nickel and iron in laterite nickel ore by deep reduction and magnetic separation

The process of deep reduction and magnetic separation was proposed to enrich nickel and iron from laterite nickel ores. Results show that nickel–iron concentrates with nickel grade of 6.96%, nickel recovery of 94.06%, iron grade of 34.74%, and iron recovery of 80.44% could be obtained after magnetic separation under the conditions of reduction temperature of 1275 °C, reduction time of 50 min, slag basicity of 1.0, carbon-containing coefficient of 2.5, and magnetic field strength of 72 kA/m. Reduction temperature and time affected the possibility of deep reduction and reaction progress. Slag basicity affected the composition of slag in burden and the spilling and enriching rate of nickel–iron from a matrix to form nickel–iron particles. Nickel–iron particles were generated, aggregated, and grew gradually in the reduction process. Nickel–iron particles can be effectively separated from gangue minerals by magnetic separation.     

梯度强磁场下Al-18%Si合金中初晶硅的细化

实验研究了梯度强磁场下Al-18%Si(质量分数)合金中偏聚初晶硅的形貌及晶粒尺寸的变化.无磁场时初晶硅为粗大的板条状或五星状;施加梯度磁场时偏聚初晶硅呈弥散分布的等轴多边形,初晶硅显著细化.当磁化力维持不变时,偏聚初晶硅晶粒尺寸随磁场强度的增大而减小,晶粒数密度随磁场强度的增加而增大.实验结果预示,强磁场影响Si原子扩散.对磁场抑制扩散及初晶硅颗粒的受力进行了分析,较好地解释了实验结果.     

Effect of excitation current intensity on mechanical properties of ZL205A castings solidified under a traveling magnetic field

The effect of excitation current intensity on the mechanical properties of ZL205 A castings solidified under a traveling magnetic field was studied. The results of the experiment indicate that the excitation current intensity of the traveling magnetic field has a great influence on the mechanical properties of the ZL205 A castings. When the excitation current intensity is 15 A, the tensile strength and elongation of ZL205 A alloy castings increase 27.2% and 67.7%, respectively, compared with those of the same alloy solidified under gravity. The improvement of mechanical properties is attributed to the decrease of micro-porosity in the alloy. Under the traveling magnetic field, the feeding pressure in the alloy melt before solidification can be enhanced due to the electromagnetic force. Moreover, the melt flow induced by the traveling magnetic field can decrease the temperature gradient. The feeding resistance will be increased because the temperature gradient decrease. So traveling magnetic field has an optimum effect on feeding.     

DZ125定向凝固合金的喷丸工艺

针对DZ125合金开展铸钢丸喷丸强化研究,分析了多种喷丸强度、覆盖率条件下合金700 ℃旋弯疲劳性能、表面残余应力和硬度梯度。结果表明:随喷丸强度的增大,中值疲劳寿命估计量逐渐增大,高喷丸强度时,700 ℃/500 MPa中值疲劳寿命估计量是原始试样的2倍;随表面覆盖率的增大,中值疲劳寿命估计量呈现先增大后稳定的趋势,当覆盖率达到400%时,中值疲劳寿命估计量达到稳定;高喷丸强度且表面覆盖率达到400%时疲劳极限为480 MPa,较原始试样疲劳极限(400 MPa)提高20%。残余应力和组织强化机制是DZ125合金喷丸的强化因素,随着喷丸强度的增大,残余压应力数值略有减小,但均明显大于原始状态;高喷丸强度时,覆盖率400%时DZ125合金表面产生超过200 μm深度的硬度场,且表面硬度较基体(430 HV0.1)提高37%。当缺口部位实际载荷大于屈服强度时,疲劳过程中残余应力和硬度都将明显松弛,经历700 ℃/600 MPa/1.5×10⁵周次的断裂试样,表面残余应力降低54%,表面硬度下降14%。