30 May 2014, Volume 45 Issue 10-磁性
    

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  • Magnetic hysteresis in microwave permeability of ferromagnetic FeCo films
    Zhe YUAN Yi YANG Dong-Ming TANG
    . 2014, 45(10-磁性): 1-0.
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    The dynamic magnetic properties of a 200-nm-thick FeCo film have been surveyed through permeability measurements in the frequency range of 0.5 to 8GHz, within a magnetic field applied in the easy magnetic direction. When the external field is inversed with the orientation of the magnetization, the increase of the field leads to the decrease of the resonance frequency according to the magnetic hysteresis that shown in the ferromagnetic films. The phenomenon can be explained by ferromagnetic resonance equations and the ratio of magnetic moments in the opposite directions has been calculated.
  • Preparation of TiAl alloy powders by reaction of titanium hydride and aluminum in high vacuum
    Zhi WANG
    . 2014, 45(10-磁性): 2-0.
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    In this paper, TiAl alloy powders were prepared through diffusion reaction in high vacuum by using titanium hydride powders of 46 micron and aluminum powders in the average of 6-8 micron by toluene. The mixed powders of titanium hydride and aluminum were investigated by SEM and XRD at different temperature and time for heat treatment. The results show that the hydrogen in the hydrogenated titanium almost could be removed clearly after heated at 500℃ for 2 hours and the alloy powders with the main intermetallic compounds of TiAl have been obtained through heated 3 hours at 750℃ in high vacuum. The size of alloy powders prepared is about 20 micron and its shape is irregular.
  • The structure and property of the Fe-6.5wt%Si-0.5wt%Cu alloy sheet prepared by warm rolling
    Zhao-yang CHENG
    . 2014, 45(10-磁性): 3-0.
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    The 0.35mm thickness Fe-6.5%Si-0.5%Cu alloy sheet prepared by hot-warm rolling has good surface quality. The microstructure of the hot-rolled sample and warm-rolled sample was observed. The vickers hardness of the hot-rolled sample and warm-rolled sample was tested. The structure and property of the Fe-6.5%Si-0.5%Cu alloy after the rolling process was investigated. Simultaneously, the magnetic properties of the warm-rolled alloy sheet was tested. The results show that, there is some slip band and only a little B2 ordered phase in the warm-rolled sample. The alloy sheet prepared by this experiment has good shape, high saturation magnetic induction and low iron loss.
  • Study on temperature characteristics of low loss FeSiAl magnetic powder cores
    . 2014, 45(10-磁性): 4-0.
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    Abstract：FeSiAl magnetic powder cores were prepared by the new type of insulating binder multilayer coating on FeSiAl powder. XRD and B-H analyzer were applied to investigate the structure, magnetic properties and temperature characteristics of the cores. The results show that the sample has the low loss with flux density from 0.01 to 0.1T under frequency between 10kHz and 200kHz at room temperature. With the increasing of temperature, initial permeability increases at first then decreases. The sample has good temperature stability according to a small temperature coefficient of permeability. At f=10kHz and B=0.2T, the power loss reaches the minimum of 93.66mW/cm3 at 10 ℃.
  • Electromagnetic and microwave absorption properties of surface modified FeSiAl micron-flakes with silane coupling agent
    Yong-Bo ZHANG
    . 2014, 45(10-磁性): 5-0.
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    Abstract The irregular FeSiAl particle is used as a raw material for ball milling with alcohol solvent to produce micron-flakes of the diameter and thickness is about 10 μm and 1μm, and then use silane coupling agent to package the flakes surface. The morphology and the element content of the packaged and unpackaged sample are investigated with SEM and XPS. The frequency-dependent complex permeability of paraffin composites with 45% volume concentration of particle is measured using the coaxial line method in 0.1?18 GHz frequency range. The real part of permittivity of the packaged composites is much lower than that of the unpackaged samples in the 0.1-5 GHz frequency range, but the permeability didn’t find obvious change. The calculation of theory of microwave transmission indicated that packaged sample has better absorbing performance than unpackaged sample in L-S frequency band.
  • Rolling process and texture evolution of 6.4wt% silicon steel with low iron loss and high magnetic induction
    Jing QIN Ping YANG
    . 2014, 45(10-磁性): 6-0.
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    6.4wt%Si high silicon steel sheets (0.23mm thick) with low iron loss and high magnetic induction were successfully produced by rolling process. The final magnetic properties along the rolling direction (RD) were: B8=1.474T, B50=1.714T; P10/50=0.30W/kg, P15/50=0.88W/kg. The texture evolution during rolling and annealing was investigated by means of X-ray diffraction and electron backscatter diffraction(EBSD). It is found that more Goss textures formed in the subsurface of hot rolled plates by using large hot rolling reduction, and then was inherited; the coarse grains in warm rolled plate were good for the formation of shear band during cold rolling; the high magnetic induction along the RD was achieved after decarburization annealing due to the formation of strong {210}<001> and Goss texture which mainly nucleated and grew within shear bands of the deformed {111}<112> grains; although some random orientation existed after final annealing, the magnetic induction was further improved due to the retention and enhancement of {310}<001> inηtexture. With the increasing of annealing temperature and annealing time, the grains of the high silicon steel sheet grew and the iron loss decreased significantly.
  • Preparation of stabilized strontium ferrite suspension and electrophoretic deposition
    Bin Peng
    . 2014, 45(10-磁性): 7-0.
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    In this paper we prepared of stable strontium ferrite suspensions. The stability of the magnetic strontium ferrite particles was increased by the addition of a surfactant dodecylbenzene sulfonic acid(DBSA). The stable suspensions of the strontium ferrite particles were obtained in 1-butanol, and these were then used for a subsequent electrophoretic depo-sition. The stability of the suspension was analyzed by zeta potential measurements. The combination of DBSA with strontium ferrite was analyzed by infrared spectrum analyzer (FT-IR). The structure of the film was analyzed by X-ray diffraction (XRD). The morphology and thickness of the film were obtained by a field emission scanning electron microscope (FESEM) and the magnetic properties of the film were analyzed by a vibrating sample magnetometer (VSM). The results showed that: electrophoresis deposition of strontium ferrite film is feasible. The zeta potential of the suspension in 1-butanol is 87 mV. The thickness of the film by electrophoretic deposition was 9.44 μm. The coercivity is 4600 Oe,with the saturation magnetization 42 A ? m2/kg and the remanence ratio 0.56.The film can be potentially applied in circulators and isolaters at microwave frequencies.
  • Preparation and Characterization of PAA/ Fe3O4 Magnetic Nanocomposite Fibers by Electrospinning
    . 2014, 45(10-磁性): 8-0.
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  • Effect of Mg2+ and Co2+ substitution on the microstructure and magnetic properties of NiCuZn ferrite nanoparticles
    Wei GUO
    . 2014, 45(10-磁性): 9-0.
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    In this paper, NiCuZn ferrite nanoparticles were prepared by chemical coprecipitation method. The effect of Mg2+ and Co2+ substitution on microstructure and magnetic properties were investigated. It was found that after appropriate content of Mg2+ and Co2+ replaced Ni2+，all the samples could still form single spinel structure. Lattice parameter and average grain size was found to increase with increasing Mg2+ and Co2+ content. TEM images show a small amount of polyhedron particles in samples, and all the samples are aggregated. Saturation magnetization was found to increase with increasing Co2+ content monotonously, and increase with Mg2+ substitution for Ni2+, up to x=0.05. When x=0.05, y=0.08 sample has the maximum saturation magnetization.
  • Normalized method for tensile characteristics of magnetorheological fluid under magnetic fields
    . 2014, 45(10-磁性): 10-0.
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    Tensile characteristics of magnetorheological (MR) fluids under tension tests over a wide applied magnetic field have been studied. Four tensile behaviors of MR fluids have been described. Normalized tensile stress and the normalized magnetic field have been proposed.The results showed that by normalizing tensile stress and magnetic field, the nature of the stress-strain curves under different initial magnetic fields during the elongations. By the electric field effect and the particle structure effect, the tensile characteristics of MR fluids under different conditions can be well compared with each other on the elongations. The exponent of tensile yield stress versus magnetic field was found to increase with magnetic field.
  • Force-sensitive properties of FeCuNbSiB powder/butyl rubber composite films
    Jia ZHOU Zhenghou Zhu
    . 2014, 45(10-磁性): 11-0.
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    Composite film was prepared by molding method with amorphous Fe73.5Cu1Nb3Si13.5B9 powder as compound phase and butyl rubber as matrix phase. The particle size is 45μm,the content of powder is 85% and the thickness of film is 150μm or 200μm.LYYL-500N high-grade type microcomputer control pressure testing machine was used to conduct program control loading with speed of 0.1mm.min-1, 0.5 mm.min-1 and 1.0 mm.min-1. Values of impedance, Z, under pressure stress were measured by TH2816LCR digital bridge with 1kHz and 50kHz.The paper study the effect of loading speed, testing frequency, film thickness and testing temperature on force-sensitive properties. The results show the force-sensitive stability property is best, when the loading speed is 0.1mm.min-1. The sensitivity(|k|) of composite films increase firstly then decrease with the increasing stress during loading process, while it increase with the decreasing stress during uploading process. While the frequency is 1kHz, The force-sensitive sensitivity of composite films are better than 50kHz. The force-sensitive sensitivity of 200μm process are superior to 150μm.The higher temperature is, the better sensitivity of composite film is.
  • Research on the low-temperature sintering and magnetic properties of yttrium ferrite doped with BaO-B2O3-SiO2 glass
    Bo ZONG
    . 2014, 45(10-磁性): 12-0.
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    The yttrium ferrite (YIG) doped with different contents of BaO-B2O3-SiO2 (BBS) glass has been prepared by the common ceramics method. The influence of the sintering temperature on the compositions and microstructure has been studied by XRD, SEM respectively, and the magnetic properties have been measured. As the results show, under the temperature of 1100 ℃, the samples generate YIG ferrite single phase. The crystalline grain grows well with the average grain size about 1.5 μm, and a small number of pores are observed. After doping BBS glass, the saturation magnetization 4πMs decreases while the ferromagnetic resonance line width ΔH increases, and the samples have bigger spin wave line width ΔHk with smaller grain size. The samples adding 2 wt.% BBS glass can be used as high-power garnet ferrite material, for the spin wave line width ΔHk is 1.01 kA/m.
  • The Formation And Thermal Stability Of Amorphous Fe52Co34Hf7B6Cu1 Alloy
    Zhang Yan-Hui chao yuesheng
    . 2014, 45(10-磁性): 13-0.
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    Amorphous ribbons Fe52Co34Hf7B6Cu1 were prepared using the single-roller melt-spinning technique. The surface linear velocity of copper wheel was 49m/s and 45m/s respectively. The adding manners of B in the amorphous are the pure B or compound FeB respectively. This research show that for the same cooling velocity 49m/s, the crystallization activation energy of prepared amorphous alloy by injecting pure B is higher than the injecting FeB, and its thermal stability is higher too. For the same injecting FeB, the crystallization activation energy of prepared amorphous alloy using 49m/s cooling velocity is higher, and its thermal stability is better.
  • Chemical Preparation of FePt Nanoparticles
    . 2014, 45(10-磁性): 14-0.
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    FePt nanoparticles possess a unique ferromagnetism and chemical stability, which show potential applications in biomedicine, data storage, permanent magnetic nanocomposites, magnetic liquid, energy catalyzer, etc., and are of the research hotspot. Chemical preparation of nanoparticles has the unique advantages, such as the accurate control of particle size and distribution, the good crystallization, and the stability. This article summarizes the FePt nanoparticle chemical preparation method in recent years.
  • Preparation and microwave absorbing properties of ultrafine nickel coating iron powder
    huifang LU Zhenghou Zhu
    . 2014, 45(10-磁性): 15-0.
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    The average particle size of 1 μ m superfine iron powder is prepared by liquid phase reduction method, and modified by nickel sulfate. The average particle size of composite powder is 2 μ m, and it has higher stability. The atlas XRD analysis found that the ultrafine composite magnetic powder by a variety of phase composition, including iron, nickel, iron and nickel solid solution, iron nickel ion compound. With high depth of field microscopy revealed in epoxy resin, ultra-fine magnetic composite powder with good dispersion, and less aggregation in an epoxy resin. Through the analysis of metallographic microscope, ultrafine composite powder is in good dispersion in the glass fiber, and aggregates smaller powder, with aggregate size of about 4 μ m. Different thickness epoxy resin glue / glass fiber composite plates (0.17mm (A), 0.26mm (B), 0.47mm (C) )are respectively prepared and tested its reflectivity. The results show that three kinds of samples all have certain absorption effect to electromagnetic wave. Sample A has certain absorption to electromagnetic wave in 2.4~6.4 GHz and 16.4~18GHz and attains the maximum value of -0.14 and -0.19 in 4.5GHz and 17.8GHz respectively. Sample B has obvious absorption to the electromagnetic wave in 1.8~5.7GHz, and achieves maximum value of -0.37 in 2.78GHz. Sample C has an obvious absorption to the electromagnetic wave in 2.2~8.9GHz, and there exists an absorption peak in 3.4GHz and 8.2GHz respectively, with peak value respectively -0.17 and -0.07.
  • Investigation of the magnetic hysteresis behaviors and magnetocaloric properties in Mn0.99V0.01CoGe alloy
    . 2014, 45(10-磁性): 16-0.
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    The magnetic hysteresis behaviors and its effect on the magnetocaloric properties for the Mn0.99V0.01CoGe alloy in the heating and cooling runs have been investigated comparatively in this paper. The magnetic hysteresis behaviors reveal an evident discrepancy between the heating and cooling processes. The average hysteresis losses estimated from the initial magnetization isotherms M (H) measured upon cooling are much larger than that upon heating. We discussed deeply the effects of the difference of magnetic hysteresis behaviors on the magnetocaloric properties for the Mn0.99V0.01CoGe alloy.
  • Experimental observation the micro-structure of MRF
    Chun-Wei ZHAO
    . 2014, 45(10-磁性): 17-0.
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    The controllable mechanical properties of Magnetorheological Fluids (MRF) mainly depend on the micro-structure inside the material. Many factors affect the micro-structure. The formation and evolution of the micro-structure was studied experimentally when the MRF was in a static magnetic field and suffering a shear. The effects of particle volume fraction and magnetic induction were considered. The results show that the number of the chains increases with the increase of the particle volume fraction, but the distance between two chains decreases with the increase of the particle volume fraction when at the same magnetic induction, the micro-structure transformed from continuous chains to get together form a glomeroplasmatic structure; at the same volume fraction, the distance between two chains increase with the increase of the magnetic induction and the polymerization degree of the chain was improved remarkably. During a shear, the dynamic evolution process of the micro-structure was observed
  • Study on the Positron Annihilation of Amorphous Fe52Co34Hf7B6Cu1 by Medium -Frequency Magnetic Pulse Treatment
    . 2014, 45(10-磁性): 18-0.
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    The amorphous alloy specimens Fe52Co34Hf7B6Cu1 were treated by medium-frequency magnetic pulse. The treatment conditions were as follows: the pulsing magnetic field frequency and the acting time were kept at 1500 Hz, 10min, and the field intensity were 200Oe, 250Oe and 300Oe respectively. The structural and structural defects of specimens before and after magnetic-pulsing were researched by M?ssbauer spectroscopy (MS) and positron annihilation lifetime spectra (PAS). The results show that in the as-quenched amorphous alloy, the positron are mainly localized at vacancy-sized free volumes in the amorphous based phase, and the amorphous alloy produced irreversible structural relaxation after being treated by the medium-frequency magnetic pulse which leaded to the decline of the annihilation lifetime t1. With the increase of pulsing magnetic field intensity, new trapping centers of positrons are produced owing to the crystallization of amorphous phase, that leads to the intensity I2 increases and I1 decreases drastically.
  • Growth and Characterization of Thick Epitaxial CdZnTe Film by Close Space Sublimation
    Yun LIN
    . 2014, 45(10-磁性): 19-0.
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    The close space sublimation method was used for the epitaxial growth of thick CdZnTe single crystal films for high-energy radiation detectors. High quality CdZnTe epilayers have been successfully grown on a GaAs(100) substrate by CSS method. Crystalline quality of the upper and lower surfaces of the epilayer was assessed from X-ray rocking curve measurements and photoluminescence(PL) spectra after GaAs(100) substrate has been removed by Chemical etching. The density of defects in the epilayer decreases with increasing the thickness, which suggests that the high-quality epilayer can be obtained by increasing the thickness. No Te inclusions in the CdZnTe films grown on GaAs(100) were observed with IR transmission imaging. The film resistivity is in the order of 10E10Ω?cm, which shows a good photoelectric property.
  • Exchange bias in NiMn-based magnetic films after laser thermal annealing
    Xuan PAN Guang-Hong ZHOU
    . 2014, 45(10-磁性): 20-0.
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    This paper deals with the exchange bias in Ni81Fe19 (15 nm) / Ni45Mn55 (x nm) bilayers annealed by laser. The influences of the laser parameters on the exchange bias (Hex) were systematic investigated. The results show that the Hex is strongly affected by the energy density of laser, and that there exists a threshold of energy density (about 150 mJ/cm2) where the exchange bias appears. With the increase of energy density, the exchange coupe becomes stronger and reaches a maximum; then it disappears gradually. In the case of the thickness of NiMn is 25nm, the Hex is 328 Oe after laser thermal annealing, which is a little higher than that of conventional thermal annealing (280 Oe). Key words: Exchange bias; laser thermal annealing; NiMn; magnetic film
  • The synthesis and electromagnetic and tribological properties of novel High Tc superconductor composite
    chen leiming
    . 2014, 45(10-磁性): 21-0.
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    High Tc superconductor composite materials was synthesized by heat pressing technique. The structure of superconducting phase was kept. The mechanical properties was improved due to the existence of Cu. So the composite material has special electromagnetic properties at low temperature. The tight relation was revealed between tribological properties and superconducting state at low temperature.
  • Hydrothermal synthesis and characterization of lead titanate perovskite tetragonal microplates
    Deng Shiqi Gang XU
    . 2014, 45(10-磁性): 22-0.
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    Abstract: Lead titanate (PbTiO3) perovskite tetragonal microplates have been successfully synthesised via a conventional hydrothermal route by employing K2Ti6O13 as titanium source. XRD, SAED, SEM, TEM and HRTEM were employed to characterize the products. The results reveal that the PbTiO3 tetragonal microplates are dominated with (101) facets. The thickness and lateral size of the PbTiO3 microplates are about 200～300 nm and 1～2μm, respctively. With the basis of the time-dependent experimental results, the formation mechanism of the PbTiO3 tetragonal microplates is discussed. Generally, the layered K2Ti6O13 plays an important role in the synthesis of the PbTiO3 tetragonal microplates. During the hydrothermal treatment, Pb2+ ions diffuse into the structure of K2Ti6O13 and replace the K+ ions, resulting in the sheet-like lead titanate species. The sheet-like lead titanate species nucleate to the intermediate phase of PbTi0.8O2.6 and then this intermediate phase transforms and grows to PbTiO3 tetragonal microplates.
  • Ionic liquid assisted synthesis and properties of mesoporous magnetic TiO2/CoFe2O4 photocatalysts
    Xiu-Ling ZHANG
    . 2014, 45(10-磁性): 23-0.
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    Mesoporous magnetic photocatalysts (IL-TiO2/CoFe2O4) were synthesized by a simple sol-gel method using 1-butyl-3-methylimidazoliun tetrafluoroborate ([C4MIM]BF4) ionic liquid as template solvents. The magnetic properties, structure and morphology were characterized by vibrating sample magnetometer (VSM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET) analysis. Photocatalytic activity of the samples was evaluated by photocatalytic degradation of methylene blue (MB). The results showed that with the assistance of ionic liquid, IL-TiO2/CoFe2O4 was mesoporous structure after 350 oC calcination and the specific surface area of IL-TiO2/CoFe2O4 was up to 125.7 m2?g-1, which was much higher than that synthesized without ionic liquid (TiO2/CoFe2O4, 46.1 m2?g-1). The photocatalytic activity of IL-TiO2/CoFe2O4 was 6 times than that of TiO2/CoFe2O4 when the calcination temperature was 350 oC. The saturation magnetization of the samples was 219 Gs, which ensured the recovery of the photocatalytic materials under the influence of external magnetic field. The samples maintain good catalytic activity after recycled three times.
  • Synthesis and sinterability of Ce0.8Gd0.2O1.9 electrolyte powder by urea low temperature combustion
    . 2014, 45(10-磁性): 24-0.
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    Gadolinia doped ceria（Ce0.8Gd0.2O1.9, GDC） is a promising candidate material for electrolyte of intermediate temperature solid oxide fuel cell（IT-SOFC）. Single-phase and ultrafine GDC powders were directly synthesized by low-temperature combustion synthesis using urea as fuel, nitrates as oxidants. XRD, TG-DSC, BET and FESEM were employed for the phase identification, the evolution behavior of the dried gel precursor，BET specific surface area measurement and morphological observations of the obtained powders, which sinterability of the GDC powder was studied. The TG-DSC result showed that the igniting temperature of urea-nitrate mixture gel was about 279.0℃。The results showed that the GDC powder with a pure cubic fluorite-type structure can be directly and rapidly synthesized through self-propagating low-temperature combustion processes under the properly selected reaction conditions. The GDC powder particles with nearly spherical shape and weakly aggregated is in the range of 20~60nm. The powders have good sinterability in the experiment and the sintered specimens with relative density was 95.2 % can be manufactured at 1300℃ for 2h under simply processing conditions. It is 300℃ lower than the sintered temperature of the powders derived from conventional solid reactions.
  • Magnetorheological Fluid Modulate Ultrasonic Propagation Characterization
    Juan WEN chang-rong liao
    . 2014, 45(10-磁性): 25-0.
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    Considering the phenomenon that the propagation characterization of ultrasonic in magneto-rheological fluid (MRF) are significantly influenced by different conditions, an experimental apparatus is designed and fabricated to study such propagation characterization of ultrasonic in MRFs. In this paper, the influences of both magnetic induction intensity and its orientation on the propagation characterization of ultrasonic in MRFs are first studied. Then an analysis for the modulation of propagation velocities and amplitudes with hysteresis of under various magnetic fields is put forward. At last, qualitative interpretations for above-mentioned characterizations are made. The investigation result shows that the propagation velocity and amplitude of ultrasonic in MRF are tightly associated with the strength of chain structures and its orientations, in which they exhibit apparent hysteresis.
  • Effect of sputtering technology on the microstructure and magnetic properties of Cu/SiO2/Ni80Fe20 composite wires
    Xiao-Qi PAN
    . 2014, 45(10-磁性): 26-0.
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    In this work, Cu/SiO2 and Cu/SiO2/Ni80Fe20 composite wires were prepared by RF magnetron sputtering on the rotating substrate of Cu. The influence of the rotating rates during sputtering SiO2 on the microstructure and Giant Magnetoimpedance (GMI) effect of the composite wires was investigated by the methods of SEM and impedance analyzer. The results showed that with the increase of the rotating rate, the particle size of the film surface first decreased and then increased, while the GMI effect of the Cu/SiO2/Ni80Fe20 composite wires first increased and then decreased.
  • The modeling process and properties of a compound soft magnetic thin film based on FeSiAl /ZnMn Ferrite
    . 2014, 45(10-磁性): 27-0.
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    This paper introduces the general magnetic properties and a new low temperature modeling process of a special compound soft magnetic film based on FeSiAl powder. In this experiment, the ZnMn ferrite soft magnetic powder with high resistivity is insulator. Waterglass is used as binder for low temperature modeling. Compared with conventional process, low temperature modeling process is compatible with micro-nano fabrication. In the end, We use microscope system VHX-2000 to observe the micro structure of the compound material. The static magnetic parameters will be tested by using the module of PPMS (Physical Property Measurement System) called VSM (Vibrating Sample Magnetometer). The dynamic magnetic parameters will be tested by the ACMS (Alternating Current Magnetization Susceptibility) instrument. In the end, we make the final practical sample with different technical elements. These elements include particle size of the powder, the content of insulator as well as the content of the binder. After test and analysis of the result data, we make conclusions on the relationship between the technical elements and its effect on the general magnetic properties.
  • Preparation of electromagnetic shielding wood-based composite by electroless Ni-Cu-P plating on fraxinus mandshurica veneer
    guo-liang li
    . 2014, 45(10-磁性): 28-0.
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    Electromagnetic shielding wood-based composite was prepared by direct electroless Ni-Cu-P plating on fraxinus mandshurica veneer as substrate pretreated with NaBH4. The effects of NaBH4 concentration, immersion time and plating time on metal deposition and surface resistivity were investigated. The morphology and structure of the composite were analyzed by using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Low-resistance measuring instrument and spectrum analyzer were used for measuring surface resistivity and electromagnetic shielding effectiveness. The results show that the metal deposition and surface resistivity of the composite is 113g/m2 and 318mΩ/cm2, respectively, when the composite was prepared under the conditions that the substrate was treated in 3g/L NaBH4 solution for 8min and plated for 25min. SEM analysis indicates that the layer deposited is uniform, continuous and compact, and the surface of the plated veneer has obvious metallic sheen. XRD analysis indicates that the layer deposited is microcrystalline state. The plated veneer exhibits electromagnetic shielding effectiveness around 55~60dB in frequencies from 9KHz to 1.5GHz.
  • Synthesis and selective adsorption properties of anionic β-cyclodextrin magnetic microspheres
    Yi-ding SHEN
    . 2014, 45(10-磁性): 29-0.
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    In this paper, anionic β-cyclodextrin magnetic microsphere（β-CDM）was prepared by using β-CD, FeCl2, Fe2(SO4)3 and Na3P3O9 as main materials. The characterization and performance tests such as X-ray diffraction (XRD), scanning electron microscope(SEM), particle size analysis, TGA and atomic absorption spectroscopy were further studied. The results show the morphology of β-CDM presents regular?spherical and the average particle size is 93.5μm. Thermal?performance increases with?increasing Fe3O4 content. It demonstrates elective adsorption for Cu2+, Mn2+ and Zn2+. The maximum removal rate of Mn2+ reaches 98.59%. The simulation results by quasi secondary adsorption kinetics show that the adsorption rate constant K2 (g·mg-1·min-1) for Cu2+, Zn2+, Mn2+ can reach 0.1851, 0.1068, 0.1584, respectively. And it takes the shortest time for Cu2+ to reach equilibrium. What’s more, recycle studies show that β-CDM is in favor of separation and regenerate under the magnetic field.
  • Effects of high-energy ball milling on microwave absorption properties of Al8Mn5 powder
    . 2014, 45(10-磁性): 30-0.
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    Al8Mn5 alloy powder was prepared by vacuum levitation melting and high-energy ball milling, Effect of high-energy ball milling on microwave absorbing properties of Al8Mn5 alloy powder were investigated with the help of scanning electron microscope （SEM） ,X-ray diffraction （XRD）and network vector analyzer. The results show that: with the increase of milling time, powder particles and grain becomes finer as powder maximum absorption peak frequency move to the low-frequency; When the sample thickness is 1.5 mm, without ball milling powder has three absorption rate more than 90% of absorption peak in the range of 13 ~ 18GHz, showing a good frequency width effect; The 24h ball milled powder has the maximum absorption peak in the 13.2GHz frequency, the reflectivity minimum -37.5dB (absorption rate 99.98%); Al8Mn5 powder absorbing mechanism of electromagnetic wave includes the electromagnetic loss in the inner of the absorber and the interference absorbing between the reflection waves from the back interface and the front interface.
  • Synthesis of magnetic metal nanoparticles by plasma and magnetic solution reaction
    . 2014, 45(10-磁性): 31-0.
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    Magnetic nanomaterials show different properties with bulk materials, because particle size and magnetic materials have the same characteristic length, for example, single domain size, superparamagnetic critical size, exchange interaction length and electron mean free path. Synthesis of metal magnetic nanoparticles is very difficult compared with oxide. Plasma and solution reaction synthesis were discussed in this work.
  • GMR/TMR Materials and Related Spintronic Devices
    . 2014, 45(10-磁性): 32-0.
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