铁粉纯度和粒径对磷化铁粉软磁复合材料磁性能的影响

研究了铁粉纯度和粒径对磷化铁粉软磁复合材料磁性能的影响。结果表明,铁粉经磷化后,表面成功包覆了完整均匀的磷酸盐绝缘层。铁粉纯度提高,软磁复合材料磁芯的密度和磁导率增大,同时磁滞损耗降低。铁粉粒度增大,磁芯密度和磁导率增加,中高频率下磁损耗明显增加,且频率越高越明显。     

铁氧体含量对Fe/NiZnFe2O4铁粉芯磁性能的影响

铁粉芯是一种具有良好软磁特性和频率特性的材料。采用放电等离子烧结(SPS)的方法制备了镍锌铁氧体包覆还原铁粉的铁粉芯,研究了铁氧体含量对铁粉芯的包覆效果和磁性能的影响。结果表明,适量的铁氧体含量有利于Fe/NiZnFe_2O_4铁粉芯的包覆和磁性能,铁氧体含量为8%时,可较好的包覆在铁粉颗粒表面,制得的磁粉芯性能最佳,具有较高的振幅磁导率μa,较低的矫顽力Hc、视在功率Ss和损耗Ps。对其损耗进一步分析发现,当频率f≤30kHz时,涡流损耗Pe占总损耗的比例40%,磁滞损耗Ph是总损耗的主要来源;当频率f70kHz时,Pe所占的比例60%,这一结果对于指导磁粉芯的应用提供了理论基础,也为进一步降低铁粉芯的损耗指明了努力的方向。     

铁硅铝/锰锌铁氧体复合软磁薄膜成型工艺及磁性能研究

研究了基于高饱和磁感应强度的铁硅铝软磁材料的复合软磁材料薄膜的低温成型工艺和磁性能。绝缘包覆工艺上,使用高电阻率的锰锌铁氧体软磁粉末做绝缘剂。粘结工艺上,使用水玻璃做粘结剂,低温固化粘结。与传统工艺比,低温成型工艺与微加工工艺兼容。应用该工艺制作了软磁薄膜,采用超景深三维显微系统VHX-2000观测复合材料的微观结构;运用振动样品磁强计测试薄膜的静态磁性能参数;使用交流磁化率测量仪测试薄膜动态磁性能参数。针对软磁磁粉颗粒度、绝缘包覆、粘结成型等不同工艺因素,制作了薄膜样品,总结了不同工艺因素对薄膜综合磁性能的影响。     

铁硅铝磁粉芯研究

采用模压成型制备了FeSiAl磁粉芯。研究了粘结剂和绝缘剂及其添加量等对其磁导率、磁损耗、品质因数Q值及压溃强度的影响规律。结果表明,当绝缘剂含量为1.0%,粘结剂含量为3.5%时,在50kHz,0.05T时的性能达到:磁粉芯磁导率达到125,磁粉芯的压溃强度可达到19.24MPa,损耗不高于80mW/cm,品质因数为41。3     

软磁Fe-Si-Al磁粉芯性能研究

研究了绝缘包覆、压制成型、退火处理对软磁Fe-Si-Al磁粉芯性能的影响.采用扫描电镜,金相显微镜,B-H分析仪和万能材料试验机检测样品的内部结构、形貌、磁性能和力学性能.研究结果表明,添加绝缘剂能够有效的降低磁粉芯的涡流损耗;增大成型压力可以提高磁粉芯的压渍强度、密度、磁导率,降低损耗和矫顽力,最佳成型压力为1800MPa;压制后的退火处理是保证磁粉芯具有较好磁性能的关键,提高热处理温度可以有效的提高磁导率,降低磁滞损耗,但过高的热处理温度会使磁粉芯的磁性能恶化,最佳的退火温度为660℃.     

磷化工艺对铁基软磁复合材料电磁性能的影响

研究了磷化工艺对铁基软磁复合材料电磁性能的影响。XRD、SEM、EDS分析和元素面分布结果表明,合适的磷化工艺能在铁粉表面生成1层很薄的非晶或纳米晶结构磷酸盐,并且包覆完整均匀。磁性能测量结果表明,室温条件下用0.01g/mL磷酸对铁粉进行磷化30min,所得到的磷化铁粉磁芯具有优异的综合电磁性能。随着磷酸浓度的增大,磷化时间的增长和磷化温度的提高,软磁复合材料磁芯的电阻率增大,中高频磁损耗不断降低,同时磁导率也有一定程度的降低。     

水雾化Fe_(74)Cr_2Mo_2Sn_2P_(10)C_2Si_4B_4非晶磁粉芯制备及性能研究

采用水雾化Fe74Cr2Mo2Sn2P10C2Si4B4非晶磁粉制备出了高频特性较好的磁粉芯。研究了样品的形貌、相组成和磁性能。研究结果表明,非晶磁粉芯压制后的去应力退火处理能够有效的提高磁导率和品质因数,过高的热处理温度会使非晶粉末晶化,析出导电性较差的非铁磁相,恶化磁性能,最佳的退火温度为400℃;绝缘包覆是制备高性能磁粉芯的必备工艺,增加绝缘剂添加量会有效的降低磁粉芯的损耗,提高品质因数,绝缘剂添加量过多会降低磁粉芯的密度和磁导率,导致综合磁性能下降,Fe74Cr2Mo2Sn2P10C2Si4B4非晶磁粉芯最佳的绝缘剂添加量为5.0%。     

低损耗ZrO2@CIPs核壳型软磁复合粉体制备及磁感应性能研究

利用正丁醇锆(TBOZ)溶液对羰基铁粉(CIPs)进行了表面改性处理。通过调整原料中TBOZ的添加量，合成了3组不同锆含量的二氧化锆包覆羰基铁粉(ZrO₂@CIPs)复合材料。分析了CIPs和ZrO₂@CIPs复合材料的静态磁性能以及绝缘性能，结果表明，使用温度提高至200℃时，ZrO₂的存在能有效抑制CIPs的氧化所导致的静态磁性恶化；且ZrO₂@CIPs复合材料的电阻率得到大幅度提升。比较包覆前后CIPs的磁损耗能力的变化，发现随着原料TBOZ添加量的增加，ZrO₂@CIPs复合材料降低磁损耗的能力增强，直流偏置特性提高。当TBOZ添加量为15.57 mL时，在频率为1 MHz时，ZrO₂@CIPs磁导率虚部仅为0.05,品质因数为116.7,饱和电流达到17.10 A。而且相较于CIPs的-0.91 V,ZrO₂@CIPs的腐蚀电位提高至-0.33 V,这无疑提高了传统CIPs的耐腐蚀性。总的来说，上述实验结果为电感领域内传统C...     

铁基软磁复合材料的SiO2包覆研究进展

软磁复合材料在诸多领域有着重要的应用，随着技术的发展，对软磁复合材料的性能要求也在不断提高中。为了满足在高频率和高功率工况下的应用需求，需要开发低损耗、高磁导率的软磁复合材料。SiO₂作为绝缘包覆介质具有高电阻率和高热稳定性，能够通过多种方法包覆在磁粉颗粒上，因此在新型软磁复合材料开发领域得到广泛的应用。总结了溶胶凝胶法、化学液相沉积法、反相微乳法、化学气相沉积法、双层包覆法和改性树脂包覆法在铁基软磁复合材料的SiO₂绝缘包覆上的应用，归纳了上述各绝缘包覆方法的特点，并按其特点进行了分类，指出了当前SiO₂绝缘包覆面临的一些问题，并对未来绝缘包覆方法的发展进行了展望。     

成型压强对FeSiB磁粉芯磁性能的影响

磁粉芯作为软磁材料的新兴发展成果相较于传统软磁材料在电力电子方面有着巨大的应用潜力。本文以气雾化FeSiB磁粉末为原料,经过预处理、包覆、成型压制和退火处理等过程制备了FeSiB磁粉芯,并研究了不同成型压强对磁粉芯磁性能的影响。结果表明,经钝化处理后的FeSiB粉末相比于未钝化粉末具有更稳定、致密的表面包覆层,提高了磁粉芯的电阻率、降低了磁损耗。对比不同成型压强下磁粉芯的磁性能,得出随着压强的增加,磁粉芯的磁导率先增加后减小,且在较宽频率范围内有着稳定的频率特性,当成型压强为1 400 MPa,f为100 kHz,B_m为50 mT时,磁粉芯表现出良好的软磁性能,其中磁导率为17.66,磁损耗为103.04 W/kg,Q值为64.34。     

Controllable SiO2 insulating layer and magnetic properties for intergranular insulating Fe-6.5wt.%Si/SiO2 composites

In this study, the intergranular insulating Fe-6.5wt.%Si/SiO₂ soft magnetic composites (SMCs) were prepared successfully using in-situ chemical deposition followed by the spark plasma sintering (SPS) process. The effects of ammonia concentration on the microstructure and magnetic properties of the composites have been studied systematically. The Fe-6.5wt.%Si alloy particles could be well insulated by the uniform SiO₂ insulating layer, and its thickness increases with increasing the ammonia concentration from 0 to 0.02?ml/g. However, further increasing the ammonia concentration to 0.03 and 0.04?ml/g would result in the discontinuous and uneven SiO₂ insulating layer. Correspondingly, the saturation magnetization and effective permeability of the composite compacts first decrease and then increase with increasing the ammonia concentration from 0.00 to 0.04?ml/g, whereas the coercivity and resistivity vary in the opposite tendency. Note that the overall performances such as the frequency stability of effective permeability, higher resistivity and lower total core loss, reach the optimal value for the sample with the ammonia concentration of 0.02?ml/g.     

Fe/Fe_(73.5)Cu_1Nb_3Si_(13.5)B_9纳米晶磁粉芯研究

采用Fe粉复合FeCuNbSiB纳米晶粉体制备了磁粉芯,并讨论了退火温度、Fe粉复合量、纳米晶粉体粒度以及绝缘剂等对磁粉芯磁性能的影响.结果表明,在200～350℃和350～400℃内退火,随着温度的升高,μ_e均呈先增大后减小,375℃时达到最佳;当复合Fe粉后,发现其软磁性能得到了明显改善, Fe粉量为40%时,μ_e达到最大,且在100kHz～1MHz内,频率稳定性良好,其中心频率在500kHz附近,并随Fe粉量的增加而向低频发生偏移.纳米晶粉体的粒度越大,磁粉芯的磁性能越好;粉体粒度为100～200目时,其μ_e达到最大.当375℃退火,由有机绝缘剂、40%(质量分数)Fe粉、100～200目纳米晶粉制备的磁粉芯,其μ_e达52.72、损耗Pu为0.01317J/m~3、Bs为3.92×10~(-3)T、Br=6.48×10~(-5)T、H_c为1.28A/m.     

High-frequency magnetic properties of Ni-Zn ferrite nanoparticles synthesized by a low temperature chemical method

Spinel-structured Ni-Zn ferrite nanoparticles (NPs) have been directly synthesized by a low temperature co-precipitation method. The structure and high-frequency magnetic properties of the particles were investigated. The as-prepared Ni-Zn ferrite NPs demonstrate typical soft magnetic properties. The saturation magnetization (M_s), as high as about 60 emu/g, was achieved. The imaginary part μ^' ' of the permeability shows a broad peak in the frequency range 200 MHz~6 GHz, which indicates that the as-prepared Ni-Zn ferrite NPs have a remarkable feature of electromagnetic (EM) wave absorption in the high-frequency range. Hence, resultant Ni-Zn ferrite NPs can be used as efficient microwave absorbers and effective heating mediators for hyperthermia application in cancer therapy.     

EDTA络合法制备Ni-Zn铁氧体及其磁学性质(英文)

以金属硝酸盐为原料,通过乙二胺四乙酸(EDTA)络合法制备了尖晶石型Ni1-xZnxFe2O4(x=0.0-0.7)晶体。通过TG-DTA考察了制备过程,采用XRD、FT-IR、SEM和VSM等对产物进行了表征,研究了热处理温度和Zn取代量对晶型结构和磁学性质的影响。同传统的固相法相比(1300℃/20h),制备单相Ni-Zn铁氧体所需的焙烧温度降至700℃,焙烧时间缩短至2h。随着Zn取代量的增加,晶胞参数递增,而矫顽力(Hc)和居里温度(Tc)逐渐下降。饱和磁化强度(Ms)随Zn取代量呈先递增至x=0.4后再逐渐下降。在1.5MHz的交变磁场中,所制粒子的感应温度接近设计的居里温度,能够适于感应加热的应用。     

Grain size effects on magnetic properties and core process of recording head Ferrites

A study has been made which correlates grain size with magnetic properties so that the proper range of grain size in ferrite materials can be determined for recording head applications. The effects of Ni-Zn and Mn-Zn ferrite grain size on 1) initial permeability, 2)B-Hloop, 3) density of ferrites, and 4) core processing, e.g., lapping and glass bonding, are described. Both experimental results and published research indicate that highly densified ferrites having larger grains are desirable for recording head applications. ASTM grain size Nos. 8-9 are therefore recommended for Ni-Zn ferrite R/W heads.     

Dispersion characteristics of the complex permeability-permittivity of Ni-Zn ferrite-epoxy composites

The effects of volume fraction and particle size of ferrite on the electric and magnetic properties of epoxy composites containing Ni-Zn ferrite were investigated. The composites were prepared by the cement mixed method and shaped as coaxial, toroidal and disc types. The complex permeability and permittivity were measured using an impedance-gain phase analyser (HP4194A) and a network analyser (HP8753C) in the frequency range 1 MHz–5 GHz.The complex permeability of the composites was found to increase as the ferrite content increased, and was characteristic of the frequency dispersion. A model to describe the frequency dispersion characteristics of the composite, which was a function of the ferrite content, is proposed here. The complex permittivity of the composite was found to be dependent mainly on the volume fraction of the ferrite and was relatively independent of frequency and particle size of the ferrite.     

Ti元素掺杂对Fe-3Si基软磁复合材料组织结构及磁特性的影响

采用气雾化制粉技术并结合模压成形方法制备xTi/Fe-3Si-0.5Al-2Ni（x=0,1,2）软磁复合材料,通过XRD、SEM、综合物性测量系统（PPMS）以及软磁交流测量仪等装置表征和分析了合金粉末的相结构、形貌、磁特性及Ti/Fe-3Si-0.5Al-2Ni软磁复合材料的磁性能,探讨了Ti元素掺杂对合金粉末居里温度、饱和磁化强度等性能的影响,并着重研究了Ti元素添加对Ti/Fe-3Si-0.5Al-2Ni软磁复合材料有效磁导率、功率损耗、矫顽力等动态磁学特性的影响。结果表明：气雾化合金粉末只存在单一的α-Fe（Si）固溶相,球形度高;Ti元素的掺杂可提高粉末居里温度,但饱和磁化强度有小幅度的弱化;另外,随着Ti元素含量的增加,Ti/Fe-3Si-0.5Al-2Ni软磁复合材料有效磁导率升高,而功率损耗和矫顽力降低,当Ti元素含量为2wt%时,软磁复合材料获得较佳的综合磁性能。     

Core-shell structured Mn-Zn-Fe ferrite/Fe-Si-Cr particles for magnetic composite cores with low loss

A Mn-Zn-Fe ferrite layer, several hundred nanometers thick, was deposited on the surface of Fe-3.5Si-4.5Cr (mass%) powder particles as an insulating material by an ultrasonic enhanced ferrite plating method. The compositions of the Mn-Zn-Fe ferrite layer were Mn_0.18Zn_0.27Fe_2.55O₄, Mn_0.38Zn_0.25Fe_2.37O₄, and Mn_0.54Zn_0.24Fe_2.22O₄. The core loss (P_cv) performances of the compacted cores and magnetic properties of the core-shell structured powders were evaluated. All the ferrite-coated cores exhibited a saturation flux density (B_s) in the range of 1.54–1.56?T derived from their soft magnetic metal and ferrite composition. All ferrite-coated cores annealed at 773?K exhibited a constant permeability µ′ in the frequency range up to 50?MHz owing to the insulating effect of the ferrite layer, and the Mn_0.54Zn_0.24Fe_2.22O₄ ferrite-coated core exhibited the highest real permeability µ′ of 56 at 50?MHz. The core loss of the Mn-Zn-Fe ferrite-coated Fe-3.5Si-4.5Cr cores was 604–738?kW/m³ at 100?kHz and 50?mT, which was much smaller than that obtained for the Fe-3.5Si-4.5Cr core without a ferrite layer (3617?kW/m³). The eddy-current loss (P_e) of the Mn-Zn-Fe ferrite-coated Fe-3.5Si-4.5Cr cores considerably decreased compared with those of the non-coated Fe-3.5Si-4.5Cr core owing to the insulating properties of the ferrite layer.