共查询到20条相似文献,搜索用时 15 毫秒
1.
Huang X Bronstein LM Retrum J Dufort C Tsvetkova I Aniagyei S Stein B Stucky G McKenna B Remmes N Baxter D Kao CC Dragnea B 《Nano letters》2007,7(8):2407-2416
Efficient encapsulation of functionalized spherical nanoparticles by viral protein cages was found to occur even if the nanoparticle is larger than the inner cavity of the native capsid. This result raises the intriguing possibility of reprogramming the self-assembly of viral structural proteins. The iron oxide nanotemplates used in this work are superparamagnetic, with a blocking temperature of about 250 K, making these virus-like particles interesting for applications such as magnetic resonance imaging and biomagnetic materials. Another novel feature of the virus-like particle assembly described in this work is the use of an anionic lipid micelle coat instead of a molecular layer covalently bound to the inorganic nanotemplate. Differences between the two functionalization strategies are discussed. 相似文献
2.
Bang Zhou Yaqiang Dong Lei Liu Qiang Chi Yiqun Zhang Liang Chang Fengqin Bi Xinmin Wang 《Advanced Powder Technology》2019,30(8):1504-1512
The Fe-based soft magnetic amorphous powder cores (AMPCs) with excellent comprehensive magnetic properties were successfully designed and fabricated using the core-shell structured FeSiBCCr/TiO2 composite powders. The influence of the concentration of water (H2O) for the magnetic performance of the AMPCs has been systematically studied based on careful analysis of the process of nucleation and growth of TiO2 under different H2O concentration in the reaction system. The growth process for the TiO2 coating layer with the H2O concentration in the range of 0.01–0.02 ml/g corresponds to the heterogeneous nucleation phase, while the mixing phase of heterogeneous and homogeneous nucleation occurs when the concentration of H2O increases to 0.03 ml/g. Optimized soft magnetic properties have been achieved for the AMPCs with H2O concentration of 0.02 ml/g, including high permeability of 81.5 with a high frequency stability up to 10 MHz, high quality factor of 102 at 530 kHz, low core loss of 42 mW/cm3 at 500 kHz for Bm = 0.01 T, and better DC-bias property of 52% at a bias field of 100 Oe due to the uniform and proper thickness insulation coating layer, which can be used to produce miniature magnetic components for applications in medium and high-frequency fields. 相似文献
3.
4.
《Advanced Powder Technology》2022,33(8):103663
In this work, a new type of FeSi/FeNi soft magnetic powder core (SMPC) was successfully fabricated by coating FeNi nanoparticles on the surface of FeSi micrometer powder. The effects of different contents of FeNi nanoparticles on the micromorphology, internal structures, and soft magnetic properties of SMPCs were studied. The results show that FeNi nanoparticles adhere to the surface of FeSi powder, which can effectively fill the air gap between FeSi powder and is beneficial to the compaction of the powder cores during the pressing process. Thus, the density of the SMPCs is increased. Compared to FeSi SMPCs, the comprehensive soft magnetic properties of FeSi/FeNi SMPCs have been greatly improved. When adding 15 wt% FeNi nanoparticles, the SMPCs exhibit excellent magnetic properties with high effective permeability (increased by 43.8 %) and low core loss (decreased by 22.1 %). The high performance FeSi/FeNi SMPCs prepared in this work are expected to be widely used in power choke coils, uninterruptible power supplies, and boosts and inverter inductors. 相似文献
5.
6.
Core-shell structured Mn-Zn-Fe ferrite/Fe-Si-Cr particles for magnetic composite cores with low loss
Satoshi Mori Takeshi Mitsuoka Kanako Sugimura Ryosuke Hirayama Makoto Sonehara Toshiro Sato Nobuhiro Matsushita 《Advanced Powder Technology》2018,29(6):1481-1486
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 Mn0.18Zn0.27Fe2.55O4, Mn0.38Zn0.25Fe2.37O4, and Mn0.54Zn0.24Fe2.22O4. The core loss (Pcv) 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 (Bs) 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 Mn0.54Zn0.24Fe2.22O4 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 (Pe) 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. 相似文献
7.
软磁Fe-Si-Al磁粉芯性能研究 总被引:6,自引:0,他引:6
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℃. 相似文献
8.
The study of granular matter composed of spherical particles is of interest in manufacturing, material, and metallurgy. The viscoelastic and frictional contacts between the particles are the cause of forming the agglomeration. We present a numerical simulation for particles packing with three different kinds of size distributions: monosize, bimodal, and Gaussian, using distinct element method (DEM). The particles are initially put randomly but without any overlap, and then fall down due to the gravity force and collide with neighbor particles. Because of the dissipative factors of viscoelastic collision and frictional force, all the particles finally come together to form an agglomeration. Coordination number, porosity, radial distribution function, and force distribution are calculated for different size distributions. It is demonstrated that particle size distribution does affect the granular packing structure. 相似文献
9.
Wang Jinghui Xue Zhengliang Song Songqiang Sun Haibo 《Journal of Materials Science: Materials in Electronics》2021,32(15):20410-20421
Journal of Materials Science: Materials in Electronics - The soft magnetic performances including frequency-dependent permeability, core loss, and DC-bias properties of the Fe-6.5 wt.%Si (FeSi)... 相似文献
10.
Z. Li K. F. Yao D. R. Li X. J. Ni Z. C. Lu 《Journal of Materials Science: Materials in Electronics》2017,28(22):16736-16740
Coercivity and losses properties of Fe80Si9B11 (at.%) amorphous cores with different radius of curvature have been studied. It shows that coercivity and core loss of the Fe80Si9B11 amorphous alloy increases with the decrement of the winding radius. The domain structure of the ribbons is different for different radius of curvature R. The domain width increases with the decrease of the radius of curvature, since the stress within the ribbon with lower radius of curvature is much stronger. Magnetic-elastic anisotropy energy has also been studied. 相似文献
11.
Particulate polymer composites consisting of Terfenol-D/Polyurethane, Fe3O4/Polyurethane, Nickel/Polyurethane and particulate composite layers were prepared by using a simple solution cast method. Magnetoelectric (ME) effect is characterized by measuring the amplitude of the magnetoelectric current versus different input parameters that appear in the theoretical current expression. The results yield two conclusions: 1.Whatever the filler type (Terfenol-D, Fe3O4 or Nickel), the microcomposites show a magnetoelectric effect. 2. The magnetostrictive property of the material does not have a direct influence on the ME effect since ME sensitivity is dc field independent and the magnetoelectric coefficient αp has close values in ac field for all types of polymer fillers. 相似文献
12.
T. Sato M. Kobayashi T. Nakagawa H. Ohsumi 《Journal of Materials Science: Materials in Electronics》1990,1(1):39-45
Magnetic properties of compacted cores which are formed from amorphous alloy powders prepared by a rapid quenching water atomization process are studied. The coercivity of the as-compacted core was estimated to beH
c=0.028(/I
s)+1200 with the idea that the coercive force depends on the magnitude of the stress variation. The a.c. magnetic properties are remarkably improved by use of the coupling agent and zinc stearate. The use of the amorphous powder core for choke coils of switching power supplies leads to the decrease of cut-off current, that is, an improvement in the efficiency of power supplies. 相似文献
13.
Bereket Yohannes Xue Liu Gary Yacobian Alberto M. Cuitiño 《Advanced Powder Technology》2018,29(12):2978-2986
We investigated the effect of particle size distribution on heterogeneity of compacted powders. We used experiments and discrete particle based simulations to compact powders, test the mechanical strength of the compact, and study the microstructure of the compact. A metallic powder which has a wide particle size distribution was used in the experiments. We found that the compaction profile is not reproducible when particles larger than 1/6 of the die diameter are present in the powder sample. The presence of these large particles generate a highly heterogeneous inter-particle contact and bonding forces. The discrete particle simulations showed that for these heterogeneous compacts the tensile strength exhibits high variability, even for one compact if the diametrical compression force is applied along different axes. Based on these results, it is recommend that the largest particle in a powder compact should not exceed one sixth of the die diameter, which is the same as the recommendation of ASTM International D4767 - 11 for compression test of cohesive soils. 相似文献
14.
It has been shown that it is possible to produce high density amorphous metal compacts on a routine basis, that have interesting soft magnetic properties. A study of some of the parameters determining their magnetic properties has been made. As expected, interparticle insulation and compact thickness affect the a.c. properties. Surprisingly, the magnetic properties were found to be relatively independent of compact density, in the range 73 to 98% of theoretical density. Low or zero magnetostriction alloys gave superior properties. If more than ~ 10% interparticle insulation is employed then the alloy composition is of less consequence. It is shown that a wide range of properties may be obtained. 相似文献
15.
用Mn-Zn铁氧体溶胶对Fe73.5Cu1Nb3Si13.5B9纳米晶包覆,模压成型制备复合磁粉芯,并研究了铁氧体溶胶量、热处理工艺及测试温度等因素对复合材料磁粉芯软磁性能的影响.实验结果表明,随着铁氧体溶胶量的增加,磁粉芯的磁导率减小,而Q值却随铁氧体溶胶量的增加有微小的增大.复合材料磁粉芯在热处理工艺为2h,500℃时,测试频率为500kHz,磁导率达到最大值.复合磁粉芯的品质因数Q值在200~1000kHz频段中,具有波动性,Q值在500kHz时达到51.测试温度对复合磁粉芯的磁导率和品质因数均有影响,测试温度从30℃升高到80℃时,磁导率从60.1降低到58.4,变化率为2.8%,而品质因数从59下降到54. 相似文献
16.
A nanopatterning method to deposit ferritin proteins with nanoscale accuracy over large areas is reported. Selective deposition is driven by the electrostatic interactions existing between the proteins and nanoscale features. Upon deposition, the protein shell can be removed by heating the patterns in an oxygen atmosphere. This leaves exposed the iron oxide core, which can be further reduced in size by plasma-etching methods. In this way, the initial ferritin molecules, which have a nominal size of 12 nm, are reduced to 2 nm nanoparticles. Magnetic force measurements confirm the magnetic activity of the as-deposited and etched nanoparticles. 相似文献
17.
18.
为了探索粉芯的新制备工艺,以Fe73.5Cu1Nb3Si13.5B9纳米晶合金铁芯为原料,使用机械破碎法制粉,并采用超重力渗流工艺制备了7种不同粒度配比的纳米晶合金粉芯,借助SEM、XRD、VSM分别对纳米晶粉末的形貌、结构和磁性能进行了表征,研究了粉末粒度配比对纳米晶合金粉芯的形貌、密度、有效磁导率、损耗及品质因数的影响。结果表明,机械破碎法制得的粉末虽带尖角,但矫顽力低,利用超重力渗流工艺制备的粉芯其粉末表面基本被树脂完全包覆。同时,通过适当的粉末粒度匹配,发现性能最佳粉芯的粉末粒度配比为:100~200目占60%,200~400目占20%,400~1 000目占20%。该种粉芯的密度为4.46 gcm3,在100~3 000 kHz频率范围内有效磁导率比较稳定,且在3 000 kHz时为28.2。当设定磁感应强度为20 mT,频率为500 kHz时,其损耗为99.1 W/kg。另外,根据实验结果可知,该工艺能够制备出频率在MHz以上具有较低损耗的粉芯。 相似文献
19.
Masanobu Kamitakahara Yuika Uno Koji Ioku 《Journal of materials science. Materials in medicine》2014,25(1):239-245
In designing the biomaterials, it is important to control their surface morphologies, because they affect the interactions between the materials and cells. We previously reported that porous calcium-deficient hydroxyapatite (HA) ceramics composed of rod-like particles had advantages over sintered porous HA ceramics; however, the effects of the surface morphology of calcium-deficient HA ceramics on cell behavior have remained unclear. Using a hydrothermal process, we successfully prepared porous calcium-deficient HA ceramics with different surface morphologies, composed of plate-like particles of 200–300, 500–800 nm, or 2–3 μm in width and rod-like particles of 1 or 3–5 μm in width, respectively. The effects of these surface morphologies on the behavior of osteoblast-like cells were examined. Although the numbers of cells adhered to the ceramic specimens did not differ significantly among the specimens, the proliferation rates of cells on the ceramics decreased with decreasing particle size. Our results reveal that controlling the surface morphology that is governed by particle shape and size is important for designing porous calcium-deficient HA ceramics. 相似文献
20.
Ni J. L. Zhu S. J. Feng S. J. Kan X. C. Liu X. S. 《Journal of Materials Science: Materials in Electronics》2022,33(2):782-788
Journal of Materials Science: Materials in Electronics - FeSi/1wt% glass soft magnetic composites are prepared by mechanically mixing, compacting, and annealing, their morphology is examined by... 相似文献