Magnetic properties of melt-spun Nd-Fe-Co-B-Cu-Nb system alloys and their bonded magnets

Melt-spun ribbons of Nd-Fe-Co-B-Cu-Nb system alloys were prepared by the single roller rapid-quenching method. The effects of composition, wheel velocity and heat-treatment on the magnetic properties were investigated. The magnetic properties of bonded magnets prepared by compression molding of optimally annealed ribbons were also measured. A maximum energy product of 152.1 kJ/m³ was obtained for the Nd₁₁Fe₇₂Co₈B_7.5Cu_0.5Nb_1.0 alloy ribbon prepared at a wheel velocity of 17.1 m/s. From the TEM observation on the above Nd₁₁Fe₇₂Co₈B_7.5Cu_0.5Nb_1.0 ribbon, the particle size of these ribbons was determined to be between 10 and 40 nm. It is conjectured that the high remanence is observed by the magnetic interaction of these fine particles, and it was found that these fine particles were achieved by Nd-Fe-Co-B compound in addition with Nb and Cu at the same time. The amorphous Nd₁₁Fe₇₂Co₈B_7.5Cu_0.5Nb_1.0 ribbons prepared at a wheel velocity of 20.7 m/s were crystallized by heat treatment, and the optimum annealing condition was found to be at 650°C for 15 min. Its corresponding value of (BH)_max is 144.5 kJ/m³. A maximum energy product of 88.1 kJ/m³ was achieved with Nd₁₁Fe₇₂Co₈B_7.5Cu_0.5Nb_1.0 bonded magnets made from the optimally prepared ribbons.     

Improvement of magnetic properties in Fe-based nanocrystalline alloys by addition of Si,Ge, C,Ga, P,Al elements and their applications

Magnetic properties of Fe-Cu-Nb-X-B (X Si, Ge, C, Ga) and Fe-Cu-Nb-Si-B-X (X: Ge, C, P, Ga, Al) nanocrystalline alloys were studied to improve soft magnetic properties and they were evaluated for some applications. Si was the best element for the Fe-Cu-Nb-X-B system. Substitution of P for B made the coercive force small in the Fe-Cu-Nb-Si-B-X system having high saturation flux density. The cores using the Fe-based nanocrystalline alloys showed low core loss, excellent dc superimposed characteristics and good noise attenuation characteristics. Hence, Fc-based nanocrystalline alloys have high performance for such magnetic components as transformers and choke coils.     

高饱和磁通密度Fe基非晶软磁合金研究进展

简要评述了高饱和磁通密度、低铁损Fe基非晶合金领域的最新进展.重点介绍了新的FeSiBC系非晶合金2605HB1的最佳化学成分、磁特性、薄带质量和关键技术,用新发展的HB1铁心制备的试验配电变压器与用常规的FeSiB系非晶合金2605SA1铁心变压器相比,显示出铁损低、工作磁感高、可听噪音低和物理尺寸小等优点.     

非晶合金铁心变压器与S11型变压器比较

通过对非晶合金铁心变压器与S11型变压器的技术性能及经济效益进行比较,阐明非晶合金铁心变压器的节能优势在技术性能上,非晶合金铁心变压器的空载损耗和有功损耗比S11型变压器低;在经济效益上,非晶合金铁心变压器的寿命比S11型变压器长5．5年左右。     

Magnetic properties of Pr‐Fe‐Co‐V‐W‐Si‐B system exchange spring magnets

The melt‐spun ribbons of Pr‐Fe‐Co‐V‐W‐Si‐B system alloys were prepared by single roller rapid‐quenching method. The effects of composition, surface velocity, and heat treatment on the magnetic properties were investigated. The P₉sFe₇₁Co₈V_0.5W_0.5Si_0.5B_10.5 alloy ribbons prepared at a surface velocity of 12.5 m/s were crystallized by heat treatment, and the optimum heat‐treatment condition was found to be at 575°C for 3 min, for which the magnetic properties were (BH)_max = 136.1 kJ/m³, J_r = 0.93 T, H_cJ = 652.2 kA/m, and H_cB = 528.3 kA/m. The temperature coefficients of J_r and H_cJ for the ribbons crystallized from melt‐spun ribbons of Pr₉Fe₇₁Co₈V_0.5W_0.5Si_0.5B_10.5 alloy were α(J_r)_ave = ?0.057%/°C and α(H_cJ) = ?0.450%/°C. The value of (B)_max for the compression molding Pr₉Fe₇₁Co₈V_0.5W_0.5Si_0.5B_10.5 isotropic bonded magnet prepared by using the ribbons annealed at 575°C for 3 min is 80.0 kJ/m³, and the density is 6.24 Mg/m³. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 157(3): 10–16, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20211 Copyright © 2006 Wiley Periodicals, Inc.     

FeZrNbBCu非晶和纳米晶合金高温磁性能研究

利用单辊熔淬法制备了FeZrNbBCu非晶薄带,然后通过非晶晶化方法得到纳米晶合金.研究了FeZrNbBCu非晶和纳米晶合金的磁性能与温度的关系.非晶态合金晶化升温过程中磁导率~温度曲线中出现了一个Hopkinson峰,而在晶化后的样品中没有出现,并根据各向异性的变化和磁化强度与温度的关系进行了合理的解释.对于非晶样品和晶相体积分数小的合金样品,当温度接近残余非晶居里温度时,磁导率急剧减小;而对于非晶相含量很少的样品,其磁导率随温度升高而缓慢下降,根据双相合金中交换作用模型进行了解释.     

铁基纳米晶软磁合金的研究现状

纳米晶软磁合金具有较高饱和磁感应强度、高磁导率、低高频损耗等特点.对牌号为Finemet、Nanoperm和Hitperm等三类铁基纳米晶软磁合金进行了分类综述,分别介绍了各类合金的成分、性能、显微组织结构特点以及应用范围,并对它们的非晶晶化过程机理以及影响合金软磁性能的因素进行了简要讨论.     

Magnetic properties of melt-spun Nd-Pr-Fe-Co-B-V system alloys and their bonded magnets

Melt-spun ribbons of Nd-Pr-Fe-Co-B-V system alloys were prepared by the single-roller rapidquenching method. The effects of composition, wheel velocity and heat treatment on the magnetic properties were investigated. The magnetic properties of their isotropic compression bonded magnets prepared from optimally annealed ribbons also were measured. Remanence (Br) was found to increase with decreasing rare-earth content, and a maximum value of more than 1.0 T was obtained. A maximum energy product of 164.0 kJ/m³ was obtained for (Nd_0.5 Pr_0.5)₉Fe₄Co₈B_7.5 V_1.5 alloy ribbon prepared at a wheel velocity of 17.1 m/s. From TEM observation, the particle size of these ribbons was determined to be between 20 to 30 nm. It is conjectured that the high remanence is obtained by the interaction of these fine particles. The amorphous (Nd_0.5Pr_0.5)₉Fe₇₄Co₈ B_7.5V_1.5 ribbons prepared at a wheel velocity of 20.7 m/s were crystallized by heat treatment, and the optimum annealing condition was found to be at 650°C for 20 min. Its corresponding value of (BH)_max was 146.2 kJ/m³. A maximum energy product of 86.4 kJ/m³ was achieved with (Nd_0.5Pr_0.5)₉Fe₇₄Co₈ B_7.5V_1.5 bonded magnets made from the optimally prepared ribbons.     

基于解析Preisach模型的非晶合金磁滞特性模拟

作为一种高磁导率、高频损耗低的软磁材料,非晶合金已广泛应用于高频变压器等电磁装置。如何准确、快速模拟其固有的磁滞特性对设备的优化设计具有重要意义。针对经典Preisach磁滞模型数值求解耗时、分布函数辨识复杂、模拟非晶合金磁滞特性精度低等问题,提出了一种可准确快速模拟非晶合金磁滞特性的解析Preisach模型。首先针对非晶合金不可逆磁化分量分布函数,基于非晶合金磁滞特性曲线实验数据利用特殊解析函数进行拟合,然后在基于积分法得到闭合形式Everett函数的基础上构建了非晶合金不可逆磁化分量。引入了含参双曲正切函数表征非晶合金可逆磁化分量,继而通过线性叠加的方式得到了解析Preisach模型。将该模型对非晶合金磁滞特性模拟结果以及损耗计算结果与实验结果进行对比,发现相对误差小于10%,并且该模型数值求解简单、易于仿真实现,具有较高的准确性与实用性。     

非晶合金配电变压器的技术性能分析

非晶合金配电变压器是一种采用新材料、新结构、新工艺的节能型配电设备,其铁心材料是一种非晶合金,与传统硅钢铁心相比,具有突出的低空载损耗特性。介绍了非晶合金配电变压器的结构特性、机械应力敏感性,分析了性能参数以及低空载损耗特性的稳定性,探讨了SH15型非晶合金配电变压器产品的有功损耗率与负载率的关系,对比分析了SH15型非晶合金配电变压器与S11型配电变压器的效率特性和年综合损耗,为评价非晶合金配电变压器的技术性能提供了参考依据。     

Study of a 18-Pulse Transformer–Rectifier Unit with an Amorphous Steel Magnetic Core

This article discusses a study of transformer–rectifier units with a magnetic core made of amorphous steel. Transformers with various types of amorphous alloys have been analyzed, and the optimum amorphous alloy for transformers was determined. Thermal processes in transformers with magnetic core of amorphous steel have been simulated, and the maximum temperature under normal operating conditions has been determined. The simulation has demonstrated that no special transformer cooling system is required. An experimental transformer–rectifier unit has been designed and manufactured with a magnetic core of amorphous steel installed on an 18-pulse rectifier with a capacity of 10.5 kV A operating with a frequency of 400–800 Hz and voltage of 115/27 V. To verify the obtained data, experimental studies have been performed that confirmed the validity of the selected design procedure of a transformer engineering flowchart. It has been demonstrated that the thermal loads detected in the transformer during testing are in the range of allowable values.     

采用非晶态合金铁心变压器时应注意的几个问题

非晶态合金（金属化玻璃）是一种优异的低损耗软磁材料。但是,在变压器的生产制造过程中,其低铁损的性能会因加工生产中的各种应力而受到影响。了解应力如何产生以及它会造成多大的影响是十分重要的。并且,应该对采用非晶合金铁心的变压器容量及其节能效果认真加以比较,根据现有的生产工艺水平作出谨慎的决策。     

Magnetic properties of iron-based materials (nitrogen interstitially modified 1:12 compounds and Fe3B-Nd) for low rare-earth bonded magnets

Hard magnetic properties of nitrogen interstitially modified NdM_xFe_12-xN_y compounds and Fe₃B-based ultra-fine crystalline Nd? Fe? Co? T? B alloys of low Nd content of 3 to 5 at. % are studied. The nitrogen-modified compounds have been prepared via the rapid solidification route and the mechanical alloying route both followed by gas nitrogenation using N₂. The Fe₃B-based materials have been prepared by means of rapid solidification and crystallization treatment. The latter materials appear promising as the base material for high-remanence, easy-to-magnetize bonded magnets with small temperature coefficients of remanence. Typical magnetic properties of compaction isotropic bonded magnets produced from this material are B_r = 0.80 T, H_cJ = 350 kA/m, and (BH)_max = 60.5 kJ/m³.     

B1 field-insensitive transformers for RF-safe transmission lines

Objective: Integration of transformers into transmission lines suppresses radiofrequency (RF)-induced heating. New figure-of-eight-shaped transformer coils are compared to conventional loop transformer coils to assess their signal transmission properties and safety profile. Materials and methods: The transmission properties of figure-of-eight-shaped transformers were measured and compared to transformers with loop coils. Experiments to quantify the effect of decoupling from the B₁ field of the MR system were conducted. Temperature measurements were performed to demonstrate the effective reduction of RF-induced heating. The transformers were investigated during active tracking experiments. Results: Coupling to the B₁ field was reduced by 18 dB over conventional loop-shaped transformer coils. MR images showed a significantly reduced artifact for the figure-of-eight- shaped coils generated by local flip-angle amplification. Comparable transmission properties were seen for both transformer types. Temperature measurements showed a maximal temperature increase of 30K/3.5 K for an unsegmented/ segmented cable. With a segmented transmission line a robotic assistance system could be successfully localized using active tracking. Conclusion: The figure-of-eight-shaped transformer design reduces both RF field coupling with the MR system and artifact sizes. Anatomical structure close to the figure-of-eight-shaped transformer may be less obscured as with loop-shaped transformers if these transformers are integrated into e.g. intravascular catheters.     

Effect of CaO and SiO2 addition on magnetic properties of anisotropic Ba-Zn system W-type hexagonal ferrite magnets

An experiment was carried out to investigate the effect of CaO and SiO₂ addition on the magnetic and physical properties of anisotropic Ba-Zn W-type hexagonal ferrite magnets. It was found that magnetic properties of BaO.2ZnO.8Fe₂O₃ compounds added with CaO and SiO₂ were improved. The optimum conditions of typical specimens are as follows: chemical analysis composition-Ba_0.857 Zn_1.643 Ca_0.150 Si_0.266 Fe²⁺_0.030 Fe³⁺_15.857 O₂₇; semisintering condition-1275°C × 1.0 h in air; sintering condition- 1250°C × in air, magnetic and physical properties are J_m = 0.436 T, J_r = 0.393 T. H_cj = 64.4 kA/m, H_cB = 64.1 kA/m, (BH)_max = 16.1 kJ/m³, T_c = 357°C, H_A = 971 kA/m, K_A = 2.03 × 10⁵ J/m³ and n_B = 33.2 μ_B.     

非晶合金配电变压器的应用及其节能分析

分析了我国农网配电变压器运行现状以及阻碍非晶合金配电变压器推广应用的因素,介绍了非晶合金材料的性能特点及国内外非晶合金配电变压器的生产技术水平和应用状况。从年运行费用、投资回收期限、效率与负载系数的关系、总拥有费用等方面对非晶合金配电变压器的节能效果进行了理论计算与分析,利用图表的形式直接反映出非晶合金配电变压器的最佳运行负载率及较好的综合经济性,为用户合理选用非晶合金配电变压器提供了依据。提出用户订购及采用非晶合金配电变压器时应注意的几点问题,针对变压器容量及安装地点的选择给出了相关建议。     

Dielectric properties of nanocrystalline barium zirconate titanate synthesized by glycine-nitrate autocombustion

Abstract

Dielectric properties of nanocrystalline barium zirconate titanate (Ba(Zr_xTi_1-x)O₃; BZT for x?=?0.1 and 0.3) synthesized by glycine-nitrate autocombustion method were investigated in this study. The phase formation examined by TGA-DTA, XRD, FT-IR and Raman spectroscopy confirmed that high purity single-phase BZT with perovskite structure was obtained by using glycine-to-nitrate molar ratio of 2.2:4 and calcining in air at 1100?°C for 4?h. TEM analysis showed that BZT had agglomerate particles consisted of primary spherical nanocrystals with the size of 8-11?nm. The diffuse phase transition behavior of BZT ceramics increased with increasing Zr concentration and for x?=?0.3, the Curie temperature; T_c, shifted to below room temperature. The BZT ceramics for x?=?0.1 had relatively high dielectric constant (ε), 13007, low T_c, 76?°C and comparable dielectric loss (tan δ) at T_c, 0.012 which caused by the high degree of Zr diffuseness into the perovskite structure. These results suggest that glycine-nitrate autocombustion is the effective method for preparing high quality BZT ceramics.     

Nb添加量对FeBCu纳米晶合金组织结构、磁性能和退火脆性倾向的影响

为改善FeBCu系纳米晶软磁合金的热处理工艺性,抑制其退火脆性倾向,利用X射线衍射仪、透射电子显微镜、差示扫描量热仪、振动样品磁强计和平板弯曲实验等测试手段,研究了Nb含量对Fe_86-xB₁₃Cu₁Nb_x(x = 0~6)急冷合金条带的结构、热性能、结晶化组织、磁性能和退火脆性倾向的影响。结果表明：增加Nb量可有效提高非晶相的热稳定性、细化热处理后合金的α-Fe晶粒尺寸并改善其软磁性和退火脆性。其效果在Nb含量＞2 at.%尤为显著,而当Nb含量 ≥ 5 at.%时趋于平缓。纳米晶合金退火脆性的改善主要源于其α-Fe晶粒尺寸和体积分数的降低。     

Nb添加量对FeBCu纳米晶合金组织结构、磁性能和退火脆性倾向的影响

为改善FeBCu系纳米晶软磁合金的热处理工艺性,抑制其退火脆性倾向,利用X射线衍射仪、透射电子显微镜、差示扫描量热仪、振动样品磁强计和平板弯曲实验等测试手段,研究了Nb含量对Fe_86-xB₁₃Cu₁Nb_x(x = 0~6)急冷合金条带的结构、热性能、结晶化组织、磁性能和退火脆性倾向的影响。结果表明：增加Nb量可有效提高非晶相的热稳定性、细化热处理后合金的α-Fe晶粒尺寸并改善其软磁性和退火脆性。其效果在Nb含量＞2 at.%尤为显著,而当Nb含量 ≥ 5 at.%时趋于平缓。纳米晶合金退火脆性的改善主要源于其α-Fe晶粒尺寸和体积分数的降低。     

Development of a New MnZn-Ferrite Soft Magnetic Material for High Temperature Power Applications

At power electronic applications (e.g. in automotive, lighting, electrical equipment etc.) the inductive components that consist the heart of the power transformers are made of ceramic ferromagnetic materials of the type (Mn_xZn_yFe^{2 +}_{1 – x – y})Fe^{3 +}₂O₄. Usually they are designed in such a way in order to exhibit optimum magnetic performance and electromagnetic power loss minimum at 80–100C, which is the steady state operation temperature region for most devices. However, the continuous miniaturization of electric and electronic equipment associated with a continuous increase in the density of electronic components has as unavoidable consequence the gradual shift of the steady state operation temperature to higher levels. The need is therefore becoming obvious for the development of new power soft magnetic materials optimized to operate at higher temperatures than those at which current existing materials operate. In the present work the development is described of such a new soft ferrite material having the chemical composition (Mn_0.76Zn_0.17Fe^{2 +}_0.07)Fe^{3 +}₂O₄, initial magnetic permeability of 1800 (measured at a frequency f = 10 kHz, an induction level B < 0.1 mT and a temperature T = 25C), Curie temperature of 225C and electromagnetic power losses < 350 mW/cm³ measured at a temperature of 140C, frequency of 100 kHz and a magnetic field strength of 200 mT. The material has been successfully introduced to production and is now commercially available. The largest application is offered by the automotive industry in particular for tackling high temperature operating problems arising when control is being done near the engine (near the engine electronics).