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磁场作用下的金属凝固研究进展 总被引:4,自引:0,他引:4
磁场作用下的金属凝固已成为金属材料基础研究和开发制备新技术的重要领域.综述了交变/旋转磁场、直流磁场作用下金属凝固的研究历史及现状,运用电磁学及金属凝固原理,揭示了磁场对凝固组织形貌及凝固过程产生的影响及主要机制,并对以后的理论研究工作提出了建议. 相似文献
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介绍了以磁阻传感器为基础的数字磁阻磁场仪HMR2300的基本原理及其在自行武器导航系统中的应用,重点叙述了在车体倾斜和有金属材料影响的情况下,对HMR2300输出结果的补偿和计算方法. 相似文献
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基于均匀梯度磁场能较准确反映出磁场影响磁性流体摩擦性能的认识,制造了一对产生均匀梯度磁场的线圈安置于改造后的UMT3摩擦试验机中。选用聚α-烯烃合成油基磁性流体为润滑油,测试不同均匀梯度磁场大小、不同载荷和不同往复频率下的磁性流体摩擦学性能。结果显示:载荷、往复运动频率一定时,磁性流体的摩擦系数随均匀梯度磁场的增大而减小;载荷、均匀梯度磁场一定时,磁性流体的摩擦系数随随往复运动频率的增大而减小;磁性流体在均匀梯度磁场中比无磁场中具有更高的承载能力和更长的耐磨寿命。 相似文献
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磁场对金属摩擦磨损影响的研究及展望 总被引:4,自引:0,他引:4
磁场对金属的摩擦学行为有多种影响,大量研究表明,在金属摩擦副接触面间加一适当的直流或交流磁场或预先将其磁化,均可明显提高其耐磨性。通过加磁场的摩擦磨损研究,可开辟一条新的防磨减摩途径。本文综述磁场影响磨损的研究方法、结果,对机制的分析及应用前景。 相似文献
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超磁致伸缩材料Terfenol-D是一种新型的功能材料,以Terfenol-D为核心元件设计各种换能器时,磁场H和应力σ是必须考虑的因素.研究了一定偏置磁场下外加压应力对Terfenol-D棒的应变和磁感应强度的影响.首先测试了在一定的偏置磁场下外压应力和应变的关系,结果表明偏置磁场一定时,应变和应力之间的关系复杂,可用磁性材料技术磁化理论来解释.其次又测试了一定偏置磁场下的外加动态应力和磁感应强度的关系,测试结果表明一定的偏置磁场下,外加压应力增加,磁感应强度减小;偏置磁场为5kA/m时,磁感应强度达到最大值.该实验结果可以为基于Terfenol-D的换能器件的设计提供技术支持. 相似文献
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磁流体密封的磁路设计及磁场有限元分析 总被引:1,自引:0,他引:1
为了在磁流体密封结构的密封间隙内获得最大的磁能积以及提高磁流体密封的耐压能力,在磁路设计理论和磁流体密封理论的基础上,对一种并联型的磁流体密封结构进行磁路设计,采用有限元法数值计算出磁流体密封结构中的磁场从而计算出磁流体密封耐压能力,并对计算结果进行了分析和讨论。结果表明:极靴与永磁体结合处的漏磁以及中间极靴轴向长度较短,导致中间极靴与两侧极靴下密封间隙内的磁感应强度差成非线性关系,也导致了磁路法低于有限元法计算出的磁流体密封耐压能力;中间极靴下密封间隙内磁感应强度较大导致两侧极靴下密封间隙内的磁感应强度差近似相等。 相似文献
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The capillary tube viscometer is used to measure the viscosity of aqueous magnetic fluids under the influence of parallel and perpendicular magnetic fields. The effects of the volume fraction of the suspended magnetic particles, the concentration of surfactants, and the external magnetic field strength, as well as the orientation, on the viscosity of the magnetic fluid are analyzed. The experimental results show that the viscosity of the sample magnetic fluids increases with increases in the concentrations of suspended magnetic particles and surfactants. The external magnetic field is also an important factor that affects the viscosity of the magnetic fluid. The viscosity first increases with the magnetic field and finally approaches a constant as the magnetization attains a saturation state. For the same magnetic fluid, the viscosity in a perpendicular magnetic field is larger than that in a parallel magnetic field for the same magnetic field.Paper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China 相似文献
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磁流体浸没物磁场力分析及磁浮特性 总被引:1,自引:1,他引:1
物体浸没于磁流体中表现出磁浮特性,对其受力状态分析是准确描述其悬浮状态的前提和基础。基于非线性磁流体应力张量模型和稳态Bernoulli方程,建立磁流体中浸没物受力模型。借助非磁性体受力模型的简化计算方法以及磁性体与磁流体之间的多场效应关系,分别对非磁性体、磁性体两类浸没物在磁流体中所受磁浮力进行分析,结果表明非磁性浸没物在磁流体中仅受到外加磁场贡献的一次磁浮力,而磁性浸没物除受到一次磁浮力外,还受到其自身激发磁场贡献的二次磁浮力.永磁体在磁流体中位置决定的磁浮力满足一定条件时,永磁体能够自悬浮于磁流体中。 相似文献
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Julia M. McCoey Robert W. de Gille Babak Nasr Jean‐Philippe Tetienne Liam T. Hall David A. Simpson Lloyd C. L. Hollenberg 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(18)
Magnetic microparticles or “beads” are used in a variety of research applications from cell sorting through to optical force traction microscopy. The magnetic properties of such particles can be tailored for specific applications with the uniformity of individual beads critical to their function. However, the majority of magnetic characterization techniques quantify the magnetic properties from large bead ensembles. Developing new magnetic imaging techniques to evaluate and visualize the magnetic fields from single beads will allow detailed insight into the magnetic uniformity, anisotropy, and alignment of magnetic domains. Here, diamond‐based magnetic microscopy is applied to image and characterize individual magnetic beads with varying magnetic and structural properties: ferromagnetic and superparamagnetic/paramagnetic, shell (coated with magnetic material), and solid (magnetic material dispersed in matrix). The single‐bead magnetic images identify irregularities in the magnetic profiles from individual bead populations. Magnetic simulations account for the varying magnetic profiles and allow to infer the magnetization of individual beads. Additionally, this work shows that the imaging technique can be adapted to achieve illumination‐free tracking of magnetic beads, opening the possibility of tracking cell movements and mechanics in photosensitive contexts. 相似文献
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《Current Opinion in Solid State & Materials Science》2013,17(4):193-201
Static magnetic field processing of non-ferromagnetic materials has been of broad interest and been applied in such fields as drug delivery, colloid chemistry and engineering of materials containing particles. A ‘strong’ magnetic field refers to a ‘strong’ response from the manipulated material and can vary in definitions. The response is corresponding to a local interaction between the material and the local magnetic field, being influenced by the magnetic susceptibilities of the material and the surrounding/coated medium. By carefully designing the medium, a significantly ‘strong’ response from a weakly magnetic material can even be generated by a traditional magnet, i.e. magnetic flux density ∼0.01 T. Therefore, the ability to manipulate materials by using a magnetic field depends critically on the understanding of the principles of the magnetic properties of materials and their magnetic responses. This paper provides a critical discussion on the principles including magnetic field effect thermodynamics, magnetic energy, magnetic anisotropy and different magnetic forces during ’strong’ magnetic field processing of weakly magnetic materials (focusing on metallic materials). A series of case studies and the related magnetic field effect are subsequently integrated and discussed. Overall this review aims to provide a better understanding and efficient overview on the phenomenon principles in the field of magnetic field processing. 相似文献
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磁性液体的磁光效应机理研究 总被引:1,自引:0,他引:1
磁性液体是一种特殊的高分子稳定胶体,对外施磁场特别敏感。通过实验观察和计算分析发现磁性液体在外施磁场下弱絮凝行为表现异常明显,又显示出特有的方向性。而且弱絮凝与絮凝不同,它不会使胶体系统失稳,合乎产生光学各向异性的事实,从而提示了磁性液体在外施磁场作用下的方向性弱絮凝是产生光学各向异性的机理。 相似文献
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对磁热疗以及纳米材料在磁热疗领域的应用情况进行了综述,着重介绍了磁流体、磁性脂质体、肿瘤靶向磁性纳米粒子及低居里点磁性纳米粒子,同时就磁性材料的发展方向进行了展望。 相似文献