The Effect of HDDR Process on Magnetic Properties in NdFeB Type of Bonded Magnets

The present paper describes the effect of alloy composition,homogenization and dehy-drogenization procedures on magnetic properties of NdFeB type of HDDR powders and the bonded magnet.The results showed that the powders prepared by HDDR process possesses useful magnetic proper- ties and a better thermal stability than the sintered NdFeB magnet does.

Demagnetization Process and Coercivity for Anisotropic HDDR NdFeB Bonded Magnets

The demagnetization process and the coercivity mechanism for amsotropic HDDR Nd(Fe,Co)B bonded magnets were studied by comparing the dependence of coercivity on the alignment field applied while the powders were pressed. The results showed that both the remanence and the coercivity of magnet increased with increasing alignment field. The demagnetization process of the magnet can be classified as the nucleation process inside the grains and the domain-wall motion between the grains. The combined effect of two processes determines the coercivity of HDDR NdFeB bonded magnets.

Magnetic Properties and Intergranular Action in Bonded Hybrid Magnets

Magnetic properties and intergranular action in bonded hybrid magnets,based on NdFeB and strontium ferrite powders were investigated.The long-range magnetostatic interaction and short-range exchange coupling interaction existed simultaneously in bonded hybrid magnets,and neither of them could be neglected.Some magnetic property parameters of hybrid magnets could be approximately obtained by adding the hysteresis loops of two magnets pro rata.

Effect of Particle Size and Distribution of Rapidly Quenching NdFeB Magnetic Powder on Magnetic Properties of Polymer-Bonded NdFeB Permanent Magnet

The effect of particle size and distribution of rapidly quenching NdFeB magnetic powder on the magnetic properties of polymerbonded NdFeB permanent magnet was studied. The results show that the particle size and the distribution of rapidly quenching NdFeB magnetic powder have significant effects on the magnetic properties of polymerbonded NdFeB permanent magnet. As long as the size and the distribution of rapidly quenching NdFeB powder are within the right range, high magnetic properties of polymerbonded NdFeB permanent magnet can be obtained. This is mainly because the rapidly quenching NdFeB magnetic powder has high hardness and is scaleshaped. The larger the size of rapidly quenching NdFeB particles is, the more difficult it is to obtain high density of bonded NdFeB magnet. However the structure will be destroyed if the size is too small. It results in the deterioration of magnetic properties. The mechanism is also discussed.

Magnetic properties and magnetization mechanism of anisotropic NdFeB/SmFeN hybrid bonded magnets prepared with different coercivity NdFeB powders

Anisotropic NdFeB/SmFeN hybrid bonded magnets were prepared by warm compaction process under an orientation magnetic field of 22 kOe,mixing with anisotropic SmFeN powders in different addition and HDDR-NdFeB powders in different coercivity.With the addition of 20 wt% SmFeN,the density and remanence of hybrid magnets increase from 5.58 g/cm~3,8.4 kGs to 6.02 g/cm~3,9.0 kGs,respectively.And as the addition amount of SmFeN powders varies from 20 wt% to 40 wt%,the maximum energy product changes less than 0.5 MGOe.In addition,the magnetization process and the interactions between two powders were studied.It is found that the magnetization process of anisotropic NdFeB powders shows distinction in different initial states.The addition of SmFeN powders promotes the rotation of NdFeB powders together with applied field,which is beneficial to the degree of alignment of NdFeB powders.Because of the micron-sized long range coupling effect,the coercivity of hybrid magnets decreases slowly with the increase of low coercivity SmFeN.Meanwhile,the magnetization process of hybrid magnets is different from pure magnets,it increases rapidly at low field and then slowly,next leads to rapidity again and achieves the saturation magnetization finally.

HDDR三元NdFeB各向异性材料的制备

研究了 ＨＤＤＲ三元 ＮｄＦｅＢ各向异性磁粉的制备工艺．发现脱氢速度对 ＨＤＤＲ三元各 向异性ＮｄＦｅＢ的磁性能具有显著影响；缓慢的脱氢处理有助于材料获得高的各向异性．在最佳 工艺条件下，可获得磁能积为 ８４ ｋＪ·ｍ３的 ＨＤＤＲ三元 ＮｄＦｅＢ各向异性粘结磁体．

粘结NdFeB磁体用偶联剂

粘结 Nd Fe B的制备工艺中磁粉的表面预处理是非常重要的 ,选用钛酸酯与硅烷偶联剂进行了对比实验。结果表明 ,经钛酸酯处理过的磁体磁性能较高 ,用硅烷处理过的磁体抗压强度较高。

注射成形法制取各向异性粘结NdFeB磁体的研究

研究了磁粉粒度、取向磁场强度、取向时间及装载量对注射成形各向异性粘结NdFeB磁体性能的影响,并分析了其原因。结果表明:NdFeB磁粉粒径太粗或太细均不利于磁体性能的提高,其最佳粒径范围是60μm^100μm;随着取向磁场强度的逐渐增加,磁体剩磁Br及矫顽力bHc增加较大但其内禀矫顽力iHc则基本不变;与此同时为保证磁粉取向完全,磁场取向时间必须大于5s。在此基础上,通过实验找出了最佳的装载量并制备出最大磁能积(BH)max和抗压强度σb分别为99kJ/m3及125MPa的高性能注射成形各向异性粘结NdFeB磁体。

NdFeB粘结磁体性能影响因素的研究

采用快淬NdFeB磁粉,通过粘结方法,制备了NdFeB粘结磁体.探讨了粘结剂、固化温度和模压压力对NdFeB磁体磁性能及力学性能的影响.试验结果表明,与液态环氧树脂相比,选择固态环氧树脂作粘结剂,可获得良好的粘结磁体磁性能和力学性能,其含量范围为2％～3％.固化工艺中的固化温度不宜过低,采用120～150℃之间为宜.在压制过程中,模压压力为600MPa时可以使粘结磁体的密度达到最佳值,且具有较好的磁性能和力学性能.

制备工艺对粘结NdFeB永磁体性能的影响

利用快淬 Nd Fe B磁粉进行了粘结 Nd Fe B磁体的制备 ,研究了磁粉粒度、成形压力、粘结剂对粘结磁体磁性能及力学性能的影响。试验表明 ,合理的粒度配比、合适的压力( 60 0 MPa)以及采用环氧值低的固态环氧树脂 。

注射成形法制备高性能粘结NdFeB磁体

利用新研制的磁场注射成形机,研究了磁粉表面改性处理、取向磁场强度及装载量对注射成形各向异性粘结NdFeB磁体性能的影响。结果表明:磁粉经硅烷改性后,可在其表面形成一层抗氧化膜,其氧化质量增加率由2.3%下降至0.35%,相应制得的粘结磁体最大磁能积及抗压强度分别提高了17.8%和35.9%;而随着取向磁场强度的增加,磁体剩磁Br及矫顽力bHc均有较大幅度的增加,但其内禀矫顽力iHc则基本不变;同时,通过实验得出了最佳的装载量为65%(体积分数),并制备了最大磁能积(BH)max及抗压强度σbb分别为99kJ/m3和125MPa的注射成形粘结NdFeB磁体。

磁粉粒度对注射成形粘结NdFeB磁体性能的影响

研究磁粉粒度对注射成形粘结NdFeB磁体性能的影响。结果表明：随着磁粉粒度减小,喂料粘度值升高,粘流指数n值降低,其注射工艺性能更好;制备粘结磁体的抗压强度更高,但其不可逆磁损失也增大。NdFeB磁粉粒度太粗或太细均不利于磁体性能的提高,其最佳粒径范围是80-100μm;通过粒度级配可以降低喂料粘度值或提高临界装载量,在此基础上制备高性能的各向异性粘结NdFeB磁体,其Br、iHc、（BH）max及σbb分别为878 mT、1 212.3 kA/m、128 kJ/m^3及73 MPa。

粘结NdFeB磁体用粘结剂

制备粘结 Nd Fe B磁体所用粘结剂是影响粘结磁体性能的关键因素。选择了五种不同的环氧树脂粘结剂制作粘结 Nd Fe B磁体 ,分析了它们对磁体工艺性能、力学性能及磁性能的影响。认为常温下为固态、环氧值较高且与磁粉表面相容性好的树脂是制备粘结 Nd Fe B磁体的理想粘结剂。

注射成型粘结NdFeB磁体的研发进展

简述注射成型粘结NdFeB磁体的制备工艺,分析了磁粉、粘结剂、取向磁场和工艺参数对注射成型粘结NdFeB磁体磁性能的影响以及该磁体的性能状况,并概述了粘结NdFeB磁体的产业发展及其应用领域,最后提出注射成型粘结NdFeB磁体的开发重点。

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。

注射成形粘结NdFeB磁体:工艺·性能·应用

综合介绍了几种适于注射成形粘结NdFeB磁体的磁粉制备方法及特点;讨论了粘结剂、改性剂及磁场取向对注射成形NdFeB磁体最终磁性能的影响及其应用市场。在此基础上,指出了今后开展研究工作的方向。

成形工艺对粘结NdFeB磁体结构和磁性能的影响

在粘结NdFeB磁体模压成形过程中存在较大的压力损失,引起磁体密度分布不均匀,致使磁体密度减小。本文研究了压制压强、预压成形和压制方式等对粘结NdFeB磁体结构和磁性能的影响及机理。研究表明:随着压制压强提高,粘结NdFeB磁体的密度和磁性能显著增大;粒度配合、预压成形和双向压制等办法均可增大粘结NdFeB磁体的密度和磁性能;在适当的压制压强下,将粒度配合、预压成形及双向压制工艺结合,制备出密度达到6.5g/cm3、磁能积达到104kJ/m3的粘结NdFeB磁体。

快淬NdFeB磁粉颗粒度对聚合物粘结NdFeB磁体永磁性能的影响

研究了快淬ＮｄＦｅＢ 永磁粉颗粒及其分布对聚合物粘结ＮｄＦｅＢ 永磁材料性能的影响。快淬ＮｄＦｅＢ永磁粉颗粒大小及其分布显著地影响聚合物粘结ＮｄＦｅＢ 永磁材料的磁性能， 适当尺寸的快淬ＮｄＦｅＢ磁粉组合可获得高性能的粘结ＮｄＦｅＢ永磁材料。这主要是由于快淬ＮｄＦｅＢ 磁粉硬度高， 呈鳞片状，其尺寸越大越难获得高密度， 但尺寸太小又将破坏磁粉的结构， 导致磁性能恶化。

不同基体粘结NdFeB磁体的磁性能及稳定性研究

通过磁粉表面处理及在NdFeB磁粉中添加不同比例的粘结剂,制备了金属基和塑料基两种粘结磁体,研究了不同基体磁体的稳定性和磁性能,从断口SEM照片及结合理论分析可得出结论:磁粉的表面处理可以改善磁体的稳定性及磁性能,通过磁性能测试及对比和退磁率的测量可以看出塑料基磁体的磁性能低于金属基磁体,但其稳定性却显著提高,塑料基磁体的使用温度可达150～180℃。