粘结NdFeB磁体的制备工艺

利用NdFeB 磁粉、聚酰亚胺制备了粘结NdFeB 磁体。研究了磁粉粒度、偶联剂用量、粘结剂用量、成型压力和粘结剂性能对粘结磁体磁性能及力学性能的影响。实验结果表明,合理的粒度配比(粗∶细为33∶67) 、偶联剂用量(磁粉0. 9 %) 、粘结剂用量(磁粉3. 2 %) 、合适的压力(600 MPa) 以及以聚酰亚胺作为粘结剂,可以获得具有较好磁性能和力学性能的粘结NdFeB 磁体。      

Demagnetization Process and Coercivity for Anisotropic HDDR NdFeB Bonded Magnets

Research Notes1. IlltroductionThe NdFeB magnetic powders produced by theHDDR (hydrogenat ion- deco mp os it ion- desorp t ionrecombination) process commonly are magneticallyisotropic. Takeshita[1] and MatzingerI2] et al. pointedout that the addition of a little Zr, Ga can inducemagnetic anisotropy for HDDR Nd(Fe,Co)B powders. In this paper, the dependence of the remanentpolarization Jr, the intrinsic coercivity jH.= and themagnetic inductive coercivity l,Hc for HDDR NdFeCoBGa bond…     

高性能三元HDDR NdFeB各向异性材料的制备

对真空HDDR方法制备各向异性NdFeB磁粉的工艺进行了改进，发现通过增加一步缓慢脱氢处理和低温氢气预处理，可使三元NdFeB合金稳定获得较高的综合磁性能。目前在最佳工艺下得到的三元NdFeB各向异性粘结磁体的磁性能为：Br=0.80T,iHc=730kA/m,BHmax=100kJ/m^3。     

NdFeB/酚醛树脂原位复合材料研究

采用原位聚合法制备了NdFeB/酚醛树脂(PF)母料,并进一步制备了粘结磁体.采用红外分析了NdFeB/PF母料的结构,并用多种方法对粘结磁体的磁性能和力学性能进行了研究.研究表明:在原位制备过程中,PF的聚合倾向于在NdFeB的表面进行,形成PF包覆的NdFeB,NdFeB磁粉进入了PF的生成体系,形成了海岛结构.比较三种工艺制备的磁体综合性能可知,采用NdFeB/PF母料粉料作粘结剂制备的磁体的综合性能最好.     

HDDR各向异性粘结NdFeB研究

本文在回顾粘结ＮｄＦｅＢ发展历程的基础上,综述了ＨＤＤＲ各向异性粘结ＮｄＦｅＢ研究现状,以及ＨＤＤＲ工艺在其它稀土永磁制备中的应用。     

环状永磁体表面径向磁通密度分布的模拟计算

利用AutoCAD软件构建四极磁环的三维模型,采用Ansoft Maxwell软件的有限元分析法对各向异性粘结钕铁硼(NdFeB)四极环状磁体表面径向磁通密度分布进行数值模拟。研究了各向异性粘结NdFeB永磁材料的剩磁B_r和矫顽力H_(cb)及环状磁体的高度、厚度和内外径,对环状磁体表面径向磁通密度与磁特性的影响。结果表明,环状磁体表面径向磁通密度与NdFeB材料的矫顽力H_(cb)及磁体的厚度密切相关,而NdFeB材料的剩磁B_r及磁体的高度对其影响较小。     

粘结剂对注射成型钕铁硼粘结磁体性能的影响

为了制备出高性价比的注射成型粘结钕铁硼永磁材料,系统地研究了粘结剂对注射成型磁体的加工性能、磁性能和力学性能等的影响。用国产的快淬钕铁硼磁粉和尼龙6粘结剂制备出了磁性能为Br:0．5158T,Hcb：321kA／m,Hcj：730kA／m,(BH)m：40kJ／m^3的注射钕铁硼磁体。     

高性能的尼龙1010 粘结NdFeB 永磁材料的制备

研究热塑性树脂尼龙1010 作粘结剂制备高密度粘结N dFeB 永磁材料的工艺及其对粘结 永磁性能的影响。结果表明: 快淬N dFeB 磁粉的表面状态、混炼工艺及热压成型温度、压力及时间 明显影响着尼龙1010 粘结N dFeB 永磁的性能。只有经抗氧化处理的快淬N dFeB 永磁粉, 在双辊 混炼机上, 当尼龙1010 处于半熔融状态时, 在适当短的时间混合均匀后, 才可热压制成高密度的 粘结N dFeB 永磁材料。      

Properties improvement and structural optimization of sintered NdFeB magnets by non-rare earth compound grain boundary diffusion

Grain boundary diffusion using rare earth (RE)-containing compounds has recently become an effective approach for improving the coercivity and reducing the heavy RE content in sintered NdFeB magnets. Here we report the enhancement of magnetic properties and corrosion resistance of NdFeB magnets by a non-RE compound diffusion process. The Dy-free sintered NdFeB magnets were coated with an MgO layer by magnetron sputtering, followed by solid diffusion heat treatment. With the successful diffusion of MgO into the magnet, the coercivity increasing from 1094 to 1170 kA/m and the maximum energy product increasing from 240 to 261 kJ/m³, together with the enhanced temperature stability and corrosion resistance, have been demonstrated. The underlying mechanisms for these enhancements have been analyzed. Microstructural investigations show that MgO entered mainly into the intergranular regions and modified the composition and structure of the grain boundary phase. The intergranular Nd–O–Fe–Mg phases observed in the MgO diffused magnet contribute to the improved performance. The current non-RE compound grain boundary diffusion process has significance in further minimizing the use of rare earth (RE).     

New kind of NdFeB magnet prepared by spark plasma sintering

We have produced an anisotropic Nd/sub 15.5/Dy/sub 1.0/Fe/sub 72.7/Co/sub 3.0/B/sub 6.8/Al/sub 1.0/ magnet by the spark plasma sintering (SPS) technique and compared it with a magnet of the same composition processed by the conventional sintering method. We investigated magnetic properties, microstructure, and constituents by a B-H loop-line instrument, a scanning electron microscope, and an energy-dispersive X-ray detector, and studied the effects of processing conditions on the magnetic properties, dimensional precision, and density. We also examined the magnet's electrochemical properties in electrolytes and its corrosion behavior in oxidizing environments. We found that the microstructure of the SPS NdFeB magnet is different from that of the conventional one. In the SPS-processed magnet, the grain size is fine and uniform while the distribution of the Nd-rich phase is heterogeneous. The SPS NdFeB magnet has a maximum energy product of 240 kJ/m/sup 3/ and a coercive force of 1260 kA/m. The density of the magnet reaches 7.58 g/cm/sup 3/, and its dimensional precision is about 20 /spl mu/m. The electrochemical properties and the corrosion resistance of the SPS NdFeB magnet are better than those of the conventional one. The SPS process is a promising method for the production of NdFeB magnets with ideal overall performance.     

塑料粘结钕铁硼的温度稳定性研究

本文研究国产快淬钕铁硼粘结磁体的温度稳定性，包括１００℃长时间时效，短时不同温度时效及温度循环对粘结钕铁硼磁损失的影响并同美国ＭＱＰ－Ｂ磁体的温度稳定性进行了比较，结果表明国产Ｍ４磁粉比ＭＱＰ－Ｂ粉具有较好的温度稳定性，Ｍ２磁粉温度稳定性较差，另外通过预先稳定化处理的方法可改善粘结钕铁硼的温度稳定性。     

温压工艺在粘结NdFeB磁体中的应用

采用温压工艺与普通压制工艺制备粘结磁体，发现温压技术可以有效地提高粘结磁体的密度，改善磁体磁性能，且温压效果与温压温度的选择密切相关。通过对温压机理的分析，发现最佳温压温度由粘结剂的软化点、粘度和固化点三个因素共同决定。采用温压工艺，在70℃、97．4NPa的条件下，得到的粘结NdFeB磁体密度、最大磁能积分为5．28kg／m^3,6．23NGOe。     

混杂粘结磁体研究

采用将不同性质的NdFeB磁粉和锶铁氧体磁粉混杂的方法制备粘结磁体,研究了锶铁氧体质量分数对混杂粘结NdFeB/锶铁氧体磁体的磁性能、温度稳定性等的影响规律,并建立了混杂磁体磁能积与锶铁氧体组分之间的经验关系式,实现了混杂磁体性能在一定范围内连续可调.     

磁性高分子粘结钕铁硼的性能

研究了二茂金属高分子铁磁粉(O PM ) 与快淬钕铁硼磁粉复合制成的一种新的粘结永磁复合材料的性能, 并与非磁性高分子粘结钕铁硼的性能进行了比较。结果表明, 磁性高分子的含量降低, 磁性高分子粘结钕铁硼永磁材料的最大磁能积(BH )_m、剩磁B_r、矫顽力Hb_c升高, 内禀矫力H j_c略为下降; 但在含相同体积分数磁粉情况下, 磁性高分子粘结N dFeB 的磁性能比非磁性的高分子粘结N dFeB 的磁性能高, 其温度稳定性也几乎相同。      

Anisotropic NdFeB Magnet Fabricated by Single Stroke Hot Deformation

1. IntroductionHard magnetic properties of the materials, such ascoercivity (He), remanence (B,), and energy product[(BH)...] depend strongly on the composition andthe processing conditionslll. The optimally quenchedmelt-spun ribbons of NdFeB alloys produced by rapidqllenching process have equiaxed and randomly oriellted NdZFe14B grains. In order to obtain anisotropicNdFeB grains, the general method is followed by hotpressing and die-upsetting of the ribbon powder oneafter anotherll'2]. …     

High Performance Sintered NdFeB Magnet

The mass production process of NdFeB magnets with energy≤MGOe and jHc≥ kOe is based on the following technological advancement: (1) effectively controlling oxygen content to less than 2000 ppm. (2) advancement of the melting technology of NdFeB alloy. (3) obtaining of a finer microstructure of the magnet. (4) finding of a new route to enhance the jHc of NdFeB magnets.     

MAGNEQUENCH ND-FE-B MAGNETS

The advent of MAGNEQUENCH neodymium-iron-boron materials having excellent magnetic properties and potential economic advantages has initiated a new era in permanent magnet technology. These magnets have already been used in cranking motors, stepping motors, etc.

Different kinds of isotropic powders have been developed having high and low coercivities for use in varied applications. The properties of these powders are discussed. The properties of fully dense isotropic (MQ2) and anisotropic magnets (MQ3) are given. Anisotropic powders produced from hot deformed magnets are stable and it contrasts sharply with those prepared from sintered magnets. These anisotropic powders can be molded into bonded magnets with energy products of 15-17 MGOe.     

阴极脉冲电泳涂层对粘结NdFeB永磁性能的影响

研究了不同工艺方法涂层环氧树脂对粘结ＮｄＦｅＢ永磁材料的耐蚀性及温度稳定性的影响。结果表明,阴极脉冲电泳法获得的环氧树脂涂层可显著地改善粘结ＮｄＦｅＢ永磁的温度稳定性和耐蚀性。     

Design and performance study of the active magnetic refrigerator for room-temperature application

A room-temperature magnetic refrigerator, consisting of permanent magnet, active magnetic refrigeration (AMR) cycle bed, pumps, hydraulic circuit, active magnetic double regenerator cycle (AM2RC) and control subsystems, has been designed. The magnetic field is supplied by NdFeB permanent magnets. The AMR bed made by stainless steel 304 encloses gadolinium particles as the magnetic working substance. Each part of the refrigerator is controlled by the programmable controller. The different standard heat exchangers are employed to expel heat. The cycle performance of this self-designed facility is analyzed using Langevin theory. The results provide useful data for future design and development of room-temperature magnetic refrigeration.     

不同表面处理工艺对快淬NdFeB永磁粉抗氧化性和磁性能影响

本文对快淬ＮｄＦｅＢ永磁粉分别采用化学镀镍,重铬酸盐钝化处理,重铬酸盐钝化还原处理以及硅烷偶联处理的重铬酸盐钝化－还原／硅烷复合处理等工艺进行了表面包覆,研究了表面包覆处理前后的快淬ＮｄＦｅＢ磁粉的抗氧化特性,并初步比较了包覆处理前后的快府ＮｄＦｅＢ磁粉制成粘结ＮｄＦｅＢ磁体的磁性能,结果表明上述工艺方法的均能改善ＮｄＦｅＢ磁粉的抗氧化性,其中以重铬酸盐钝化－还原／硅烷偶联处理形成的包覆层的抗氧化