烧结钕铁硼微观组织对磁性能的影响

研究了不同烧结和时效工艺的N35(16.70Nd，16．50Pr，0．30Dy,1．15B，0．30Al)和N30(10．60Nd，23．40Pr，0．30Dy，1．20B，0．30Al)两种牌号钕铁硼磁体的晶粒大小和形态对磁性能的影响。结果得出：剩磁Br随晶粒尺寸的增大有极大值，内禀矫顽力Hcj及最大磁能积BHm随晶粒尺寸的增大而降低。高磁能积磁体的最佳组织为晶粒均匀、细小、呈球形，没有聚集成块的富钕相和富硼相存在。     

Interaction of Microwave Magnetic Field With Materials

Microwave is an electromagnetic wave and consists of the electric and the magnetic fields.The microwave electric field interacts with dielectric materials and heat is generated due to the dielectric loss,which is a major mechanism of microwave heating of water.Microwave magnetic field interaction with materials has to be discussed in terms of two different mechanisms.The first class is the induction current generation in（mainly）metallic materials,which gives rise the Joule heat,although the penetration distance into metals are limited within a microns or less.In this article,a characteristic application of microwave induction heating of metal thin film is presented.The second class is the microwave interaction with the ferro（or ferri）magnetic materials.Effect of ferromagnetic resonance（FMR）is taken into consideration as the fundamental heating mechanism of the ferro-magnetic materials.The FMR heating behavior of Fe₃O₄ is presented.Discussion is made for the phenomena observed in the experiments.     

压坯密度对烧结NdFeB磁体磁性能的影响

采用速凝片（SC）、氢破（HD）和气流磨（JM）工艺制备钕铁硼磁粉,研究了压坯密度、烧结温度对磁体取向度、微观结构和磁性能的影响。结果表明：选择合理的压坯密度（ρx=3．4g／cm3）可以使磁体在模压和液相烧结过程中保持较高的取向度,剩磁提高约2％。在低温度（1055℃）烧结时,可以获得较为理想的显微组织,主相晶粒细小...     

Effect of Particle Size and Distribution of Rapidly Quenching NdFeBMagnetic Powder on Magnetic Properties of PolymerBonded NdFeBPermanent Magnet

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热处理对高矫顽力型FeCrCo合金性能的影响

讨论了一种高矫顽力型FeCrCo合金。合金的成分与常见的FeCrCo相比有较大调整 ,Cr,Co的含量较高 ,加入了Mo ,Zr等微量元素 ,它的矫顽力值可达 72～ 80kA·m- 1 ,有利于扩大其应用范围。实验从合金的热处理工艺入手 ,即传统的 3步热处理 :高温固溶处理、磁场等温处理、分级回火处理 ,通过不同的实验条件下合金的性能变化情况阐明合金实用的处理工艺。     

成型工艺对粘结钕铁硼永磁材料磁性能的影响

采用由熔体快淬法制备的不同粒度大小的M Q粉搭配,分别与粘结剂和一些助剂(固化剂、润滑剂等)按照一定的比例混合,放入模具中,在不同压力下压制成所需要的形状,加热到一定的温度固化。结果表明,磁粉的粒度搭配、成型压力是影响磁性能的重要参数。     

成形压力对烧结Nd-Fe-B磁体微观组织与磁性能的影响

在于法制备烧结钕铁硼生产线上,研究了11.54 MPa和9.23 MPa两种成形压力对Φ9.5mm烧结钕铁硼磁体(/%:31.00Pr+Nd、1.20B、0.20Al、余Fe)微观组织与磁性能的影响。结果表明,成形压力增大可以改善晶粒分布的不均匀性,提高取向度,从而提高剩磁与磁能积;但成形压力增大易使晶粒尺寸增大,从而使矫顽力降低。     

Effect of HD Process on Microstructure and Hard Magnetic Properties of NdFeAlB Magnet

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添加Ga、Nb对NdDyTb-FeCo-B烧结磁体显微组织和磁性能的影响

研究了复合添加Ga、Nb对NdDyTb-FeCo-B烧结磁体的显微组织和磁性能的影响。结果表明:添加0.1%Ga、0.5%Nb磁体的矫顽力iHc、剩磁Br、最大磁能积(BH)max均较好。用SEM电镜对显微组织进行分析,发现添加Ga后晶粒大小均匀,形状规则化。在烧结过程中Ga原子置换Nd2Fe14B相中Fe原子形成Nd2Fe14-xGaxB二次主相,使反磁化核不易形成和扩展,从而改善磁体的磁性能。     

深冷处理对纳米复合永磁材料织构度和磁性能的影响

利用熔体快淬技术制备了(N d11.4F e82.9B5.7)0.99Z r1,(N d11.4F e82.9B5.7)0.99G a1和P r8F e87B5快淬带。利用深冷技术对纳米晶复合快淬带进行超低温处理。研究了深冷处理对纳米复合永磁材料织构度和磁性能的影响。结果表明深冷处理有助于快淬带织构度的增强,使快淬样品的饱和磁化强度Ms发生变化,矫顽力Hci变化不大。经深冷处理后P r8F e87B5样品最佳(BH)m ax达到187.9kJ.m-3。     

矿石粒度对活性炭催化低品位原生硫化铜矿石细菌氧化的影响

通过摇瓶试验,研究了矿石粒度对活性炭催化原生硫化铜矿石细菌氧化浸出的影响。结果表明：在活性炭催化低品位原生硫化铜矿石细菌浸出过程中,矿石粒度对铜的浸出率有较大影响。矿石粒度小于0．1mm最有利于铜的浸出,浸出240h,铜浸出率达83％;矿石粒度过细,溶液中三价铁含量升高,产生的铁沉淀物会直接影响铜的浸出。     

永磁式核磁共振成像仪(MRI)磁系的研究

研究内容为研制一种可以在气隙中获得较大范围的均匀高磁场区的永磁磁系.磁系由一系列扇形钕铁硼磁体组成,这些磁体的磁化方向沿圆周方向等角度渐变,形成两个磁极,磁场方向垂直于轴向.圆筒形磁系在沿轴方向加以分层,调节层数及每层厚度以获得均匀磁场.利用“磁荷”概念及磁库仑定律计算磁场.     

Numerical Simulation of Magnetic Field Distribution in Aluminum Melting Furnace With Electromagnetic Stirring

In metallurgical processing,effective and reliable electromagnetic stirring of the melt is one of the prerequisites for higher productivity and improved process performance.Reasonable structure and electrical parameters of the stirrer are greatly significant on improving and enhancing the stirring quality.In this paper,ANSYS software is used to research the effect of stirrer parameters on magnetic field distribution in aluminum melting furnace.The results show that magnetic flux density distributes as two humps at the direction(X)of metal length.Magnetic flux density distributes as a hump at the direction(Z)of metal width,reaches its maximum at the pool center and decays gradually toward the edge.It is also demonstrated that magnetic flux density increases by 2.65mT,as kilo-ampere-turns increase by 2.The center distance between two coils changes the distribution of magnetic flux density rather than its magnitude,while the distance from coils to the bottom of molten aluminum changes the magnitude of magnetic flux density but no change of distribution.     

高磁能积低温度系数的铁基永磁合金的磁性能与组织结构

本文研究了Co和Al的添加对NdFeCoAlB永磁合金磁性能与组织结构的影响。获得一种磁能积为278.6~318.4kJ/m³(35~40MGOe),磁感可逆温度系数α293~373K=-0.06~-0.08%/K的NdFeCoAlB系5元合金。Co主要进入四方相,提高合金的居里点,降低磁感可逆温度系数。当含Co量较高时,在合金中形成了具有MgCu₂型结构的Nd(FeCo)₂相,使合金永磁性能恶化。Al主要进入四方相,使四方相晶粒和富B相块度细化,提高了合金的矫顽力。进一步提高Al含量时,在合金中形成了新相,使合金永磁性能恶化。     

机械活化黄铁矿的储能研究

采用自行研制的机械化学热量仪在303.15 K下对机械活化黄铁矿进行了在线储能研究。结果表明:湿磨时黄铁矿最大储能为361.5 J/g,活化效率为20.5%;干磨时黄铁矿最大储能为338.3 J/g,活化效率为16.1%。粒度和X射线衍射分析表明,活化后黄铁矿粒度减小,晶格发生畸变。     

Kinetics of Thermally Activated Lattice Softening in Titanium: A Dynamic Calorimetry Study

The thermally-activated lattice defect relaxation kinetics in 90 % cold-rolled titanium has been investigated through differential scanning calorimetry, isothermal aging experiments, supplemented by metallography and theoretical modelling. Calorimetry results revealed two major softening thermal arrests at 755 and 944 K, respectively, marking the onset of recovery and recrystallization of deformed state. Adoption of higher heating rates resulted in overlapping of recovery and recrystallization; in fact, the excess unspent driving force due only to partial recovery accelerated the recrystallization. Standard isoconversional analysis of calorimetry data yielded 115 and 147 kJ mol^?1 for apparent activation energies of recovery and recrystallization, respectively. These values agree well with the results of an independent analysis of time, temperature variation of hardness of isothermally annealed samples.     

Magnetic Domain Structure: Analysis of Magnetic Reversal in RE-3d Permanent Magnets

The possibilities of direct magnetic domain observation on surfaces of modern permanent magnets SmCo₅, Sm-Zr-Co-Cu-Fe, Nd-Fe-B by means of the magneto-optical Kerr effect for the quantitative and qualitative testing of magnetization and magnetic reversal processes and nature of magnetic hysteresis were analyzed. For all types of investigated magnets, the angular dependences for saturation field H_S, critical field of reverse domain removal H_K, and nucleation field H_n of individual grains were found to obey the law 1/cosϕ, where ϕ is the angle between the grain easy axis and external magnetic field.     

快淬NdFeB磁粉的磁选分离

快淬NdFeB磁粉的制备过程中有许多因素影响磁粉性能的均匀性 ,致使出现部分低性能的磁粉 ,磁选可把低性能的磁粉分离出来。研究了磁选时辊轮转速、磁选次数以及磁场强度对快淬Nd9.5(FeCoZrAl) 84 .5B6 磁粉分离效果的影响。研究表明 ,选择合适的磁选工艺参数能有效分离低矫顽力的磁粉。与未磁选的Nd9.5(FeCoZrAl) 84 .5B6 磁粉制作的粘结磁体相比 ,磁选后的磁粉制作的粘结磁体磁性能有较大的提高 ,最佳磁性能为 :Br=697.4mT ,Hcb=44 2kA·m- 1 ,Hcj=741kA·m- 1 ,(BH) max=77kJ·m- 3。     

室温磁制冷磁体用量的估算

根据主要的永磁体材料磁化性质和可能的室温磁制冷材料的磁热性质,利用磁路定理并假定了通常使用的循环换热流体的压力差上限来计算磁制冷功率和永磁体体积之间的关系,进而说明室温磁制冷机的制冷量的受约束情况以及实用可能性。通过对两种典型的磁路进行的计算对比,发现在使用高磁场时使用中空圆柱形磁聚焦方式更有效,而在获得低于1T的磁场时普通的救生圈环形磁路更为有效。