温压压力对钕铁硼磁性能和抗压强度的影响

为了制备高性能的粘结磁体,改善有机粘结剂粘结磁体的不足,采用粘结的方法使用金属Sn作为粘结钕铁硼磁体的粘结剂,通过温压设备进行双向模压成型制备磁体,讨论了温压压力对粘结钕铁硼磁体的磁性能和抗压强度的影响规律。研究表明,当温压压力达到1 400 MPa时,磁体具有较佳性能:磁体密度ρ为6.492 g/cm3,剩磁Br为0.789 T,内禀矫顽力Hcj为719 kA/m,最大磁能积(BH)m为110.9 kJ/m3,抗压强度fc为81.5 MPa。     

NdFeB磁粉对粘结NdFeB/锶铁氧体复合磁体性能的影响

采用流动温压成型技术制备了各向同性粘结NdFeB/锶铁氧体复合磁体。研究了不同类型NdFeB磁粉对粘结NdFeB/锶铁氧体复合磁体磁性能和交换耦合作用的影响。结果表明,粘结贫稀土NdFeB/锶铁氧体复合磁体的综合磁性能最好,当NdFeB和铁氧体的质量比为3:2时,其磁性能Br=0.38 T,Hcj=524 kA/m,(BH)max=21.9 kJ/m3;另外,其Henkel曲线为典型的S型曲线。粘结纳米双相NdFeB/锶铁氧体复合磁体内的交换耦合作用近乎消失,磁体内以静磁交互作用为主。     

添加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磁体,采用国产的快淬钕铁硼磁粉和尼龙6混合、挤出造粒后,注射成型制备钕铁硼磁体。通过对硅烷系列的偶联剂、硬脂酸系列的润滑剂等添加剂对注射磁体性能的影响研究,并结合微观分析优化出了各种添加剂的最佳添加量,制备出了磁性能为Br:0.5158T,Hcb:321kA/m,Hcj:730kA/m,(BH)m:40kJ/m3的注射钕铁硼磁体,磁体的性能与日本Mate公司的RNI—50产品性能相当,而价格却低得多。     

我国钕铁硼永磁材料产业技术现状与发展趋势

简述了我国钕铁硼永磁材料产业技术现状,针对存在的高磁能积、高矫顽力、产品一致性好烧结钕铁硼磁体生产工艺不稳定以及各向异性粘结钕铁硼磁体产业化技术不成熟等问题,提出了可通过改善烧结钕铁硼制备工艺、开发耐高温高矫顽力烧结钕铁硼以及加大各向异性粘结钕铁硼产业化技术研究来提升我国钕铁硼永磁材料产业技术水平。     

脱氢处理对烧结NdFeB磁体性能的影响

研究了氢爆工艺中脱氢程度对烧结NdFeB磁体性能的影响。结果指出，脱氢程度越大，磁体的磁能积和矫顽力也越大。样品不脱氢时，磁体内出现大量微裂纹，这是由于烧结时放气量太大的缘故。研究结果表明选择合适的脱氢量是氢爆工艺中一个重要的因素。     

成型工艺对粘结NdFeB磁体力学性能的影响

用模压成型方法制备了粘结NdFeB磁体,通过对磁体密度、抗弯强度和抗压强度的分析,研究了A、B和C三种成型工艺对磁体力学性能的影响。结果表明:工艺B制备的磁体密度最大,磁性能最好;工艺C制备的磁体力学性能最好且制备成本低,生产效率高,适合大批量工业化生产;工艺C制备的磁体,620MPa成型压力和160℃固化温度使磁体获得最优的力学性能,其抗弯强度、抗压强度分别达到了76.63,154.63MPa。     

磁性材料、超导材料和器件

TM271 2002060054HDDR三元Nd凡B各向异性材料的制备/韩景智,孙爱芝,刘涛,肖耀福,王润(北京科技大学)11北京科技大学学报.一2002,24(2)一137一140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84kJ·m3的HDDR三元NdFeB各向异性粘结磁体图7表1参8(木)P rZ(FeCo)1。B/a一(Fe,Co)纳米复合永磁合金的组织与磁性/包小倩,张茂才、刘湘华,乔yi,高学绪,周寿增(北京科技大学)“北京科技大学学报.一2…     

AlNiCo5与AlNiCo9显微结构与磁性能研究

对比研究了AlNiCo5和AlNiCo9两种磁体的显微结构和磁性能。结果表明:常温下,AlNiCo5磁体易磁化方向的剩磁明显高于AlNiCo9,但矫顽力和最大磁能积较低,AlNiCo9的矫顽力为125.34 kA/m,最大磁能积为77.99 kJ/m~3。利用XRD研究AlNiCo5和AlNiCo9磁体的相结构,发现两者均存在强磁性α_1相和弱磁性α_2相,且均为体心立方结构。利用透射电子显微镜观察发现AlNiCo9磁体中的α_1相均匀分布在α_2相中,且两个α_1相之间Cu、Ni的聚集起到了桥梁的作用。利用磁力显微镜观察两种磁体的磁畴形貌,发现AlNiCo9的磁畴呈现球形的迷宫状,AlNiCo5呈现为长条状。     

NdFeB永磁材料电场烧结与传统烧结的对比研究

分别采用电场烧结与传统烧结工艺方法制备了NdFeB合金,通过对烧结体的SEM分析和热分析,对其微观结构、磁性能及耐蚀性作了比较。结果表明:电场烧结磁体的富Nd相更细小,分布更弥散、更均匀,磁体的相结构与传统烧结磁体基本相同,没有新相生成;电场烧结磁体回火态(BH)max为270kJ/m3,高于传统烧结磁体(256kJ/m3),耐蚀性更强。NdFeB的电场烧结工艺生产周期短、生产效率高、能源消耗少、制造过程控制更加容易。     

快淬钕铁硼磁粉粘结磁体的SEM分析

快淬钕铁硼的磁粉与粘结钕铁硼磁体的粘结剂是影响粘结磁体性能的关键因素。本文应用KYKY-2800型扫描电子显微镜，对快淬钕铁硼磁粉的粘结钕铁硼磁体进行了研究，分析认为，除了磁粉的磁性能外，原料粉的形态、粒度的分布及成型磁粉的完整性均对磁体性能有影响。     

球磨与共沉淀法制备MnZn铁氧体的对比研究

分别采用高能球磨和化学共沉淀法制备了MnZn铁氧体,通过XRD、VSM和金相显微镜的分析,对两种铁氧体的预烧料粉末、烧结体的显微结构以及磁性能做了比较。结果表明:化学共沉淀法所制备的预烧料粉末具有晶粒细小、均匀和活性高等优点;与高能球磨法相比,化学共沉淀法烧结磁体的密度较高、晶粒尺寸较大,磁性能更为优良。其相应的磁性能参数Ms、Mr、Hc和μi分别为3.845×102kA/m,3.421kA/m,0.722kA/m和5500。     

Superconducting magnet system containing Bi-2212/Ag Coil Generates 21.8 T at 1.8K

We fabricated a Bi-2212/Ag double stacked pancake coil of 13 mmØ) in inner bore and of 46.5 mmØ in outer diameter, by using Bi-2212/Ag tapes prepared by the combination of continuous dip-coating process and melt-solidification technique. This small superconducting magnet was used as an insert magnet of a conventional superconducting magnet system and tested at saturated superfluid helium temperature (～ 1.8K) in various bias fields. The generated field of Bi2212/Ag coil was 0.9 T, with I_c of 310 A(criterion 10^-13Ω·m), in the bias field of 20.9 T. Thus, this superconducting magnet system achieved generation of magnetic field of 21.8 T in the full superconducting state.     

Free electron laser small signal gain measurement at 10.6 µm

Small signal gain has been observed for 10.6 μm radiation using a constant (untapered) wiggler. The permanent magnet wiggler was 2.65 m long, had a period of 3.56 cm (75 periods) and a magnetic field on axis of 2.67 kG. The gain measured was 1.5 ± 0.4 percent agreeing well with the predicted gain corresponding to the experimental electron beam conditions (E = 25MeV,DeltaE/E = 0.75percent,epsilon = 8pimm . mrad, andI = 10A).     

Quench performance and mechanical behavior of the first Fermilab-built prototype high gradient quadrupole for the LHC interaction regions

As part of the US LHC program to provide high gradient superconducting quadrupoles for the LHC interaction regions, a 5.5 meter long prototype magnet has been built and tested horizontally in a production type cryostat at Fermilab. This prototype magnet was used to validate the mechanical and magnetic design, production fabrication and assembly tooling. The first prototype magnet has met the LHC requirements of operating at 215 T/m with excellent magnetic field harmonics. This paper summarizes the test results of this magnet, including quench tests and mechanical behavior over several thermal cycles.     

Minimum Stored Energy High-Field MRI Superconducting Magnets

A globally optimum minimum stored energy optimization strategy is implemented to design actively shielded superconducting magnet configurations used in high-field applications. The current density map is first obtained and used as a foundation for the magnet configurations by placing coils at current density local extremities. Optimized current density maps based on the stored energy formulation along with final magnet arrangements are provided to illustrate the findings. In this work, the focus was on compact superconducting magnets as measured by physical size and system footprint for given magnetic field properties inside the imaging region. The process of obtaining the current density maps proposed here over the given magnet domain, where superconducting coils are laid out, suggests that peak current densities occur around the perimeter of the domain, where in the most compact designs, with the domain length less than 1 m, the current direction alternates amongst adjacent coils. To reduce the peak magnetic field to acceptable levels on the superconductors in high-field designs, the size of the magnet domain is made larger, to the extent that the current densities no longer alternate between coils.      

纳米添加剂对永磁铁氧体微结构与性能的影响

通过高能球磨将添加剂纳米化,研究了其对永磁铁氧体(样品)磁性能和微观结构的影响。结果表明:添加剂的平均粒度从216.448μm减小到65nm时,有效降低了磁体的熔点,提高其致密化。1190℃烧结时磁体的Br和Hcj分别从404mT、366kA·m–1提高到418mT和402kA·m–1。SEM观察样品晶粒平均粒径在1~2μm,晶粒分布更加均匀。取向度从75.2%提高到84.0%。     

Construction and Testing of the Final Focus Quadrupole R&D Magnet for the Super-KEKB Interaction Region

Super-KEKB is designed to be a next generation particle accelerator with a target luminosity of 4 times 10³⁵ cm^-2s^-1. For the interaction region, a final focus quadrupole R&D magnet was designed and constructed. The design field gradient and effective magnetic length were 40.12 T/m and 0.299 m, respectively. The magnet consists of 6 layer coils. After construction, the magnet was tested at 4.2 K and a preliminary field measurement was performed. The magnet was energized to a current of 1800 A, which corresponds to 95.8% of the conductor limit, and the quadrupole component error was 0.23 % of the design value.     

铁基非晶软磁合金的制备及磁性能研究

研究了铁基非晶(Fe1–xCox)78.4Nb2.6Si9.0B9.0Cu1.0(x=0,0.15,0.35,0.55或0.75)软磁合金的制备工艺及磁性能。结果表明:采用熔体快淬法制备的非晶薄带宽约3mm,厚20～40μm;最佳工艺参数为铜轮转速35m/s,熔体射流压力0.14MPa;借XRD分析了合金的相结构,发现合金薄带为非晶态;通过振动样品磁强计(VSM)测量了磁性能,其Bs大于1.00T,Hc为2.31～5.17kA/m。用畴壁钉扎效应分析了Hc偏高的原因。