The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Hyoung Jin Choi - One of the best experts on this subject based on the ideXlab platform.
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effect of octahedral typed Iron oxide particles on magnetorheological behavior of Carbonyl Iron dispersion
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018Co-Authors: Seung Hyuk Kwon, Hyoung Jin Choi, Hyo Seung Jung, Zbynek Strecker, Jakub RoupecAbstract:Abstract To enhance suspension stability and magnetorheological (MR) effect of Carbonyl Iron (CI)-based MR fluids, octahedral-shaped magnetite particles were synthesized by a hydrothermal method in an autoclave and then adopted as an additive for soft-magnetic CI-based MR suspensions. Two different MR suspensions comprised of the same CI particles with a 70% weight fraction were prepared; one contained an additional 1 wt% octahedral magnetite according to the carrier fluid weight. The MR characteristics of the two MR suspensions with and without the octahedral-typed magnetite nanoparticles were tested using a rotation-typed rheometer attached with a magnetic field strength generator. The sedimentation profile of the MR suspension with and without the additive was also analyzed. The shear viscosity, shear stress, yield stress, and storage modulus from rheological tests were enhanced by the magnetic additive.
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effect of cofe2o4 nanoparticles on a Carbonyl Iron based magnetorheological suspension
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018Co-Authors: Yu Zhen Dong, Shang Hao Piao, Ke Zhang, Hyoung Jin ChoiAbstract:Abstract Magnetic CoFe2O4 nanoparticles were successfully fabricated by a non-aqueous hydrothermal method and used as an additive in a micron-sized, Carbonyl Iron (CI) based-magnetorheological (MR) fluid to improve its dispersion stability and MR characteristics. The morphology and magnetic properties of CoFe2O4 were demonstrated by using X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. The results showed that CoFe2O4 was synthesized successfully with a nearly spherical morphology and excellent crystalline structure. The saturation magnetization (Ms) of the CoFe2O4 was also about 74.4 emu/g. The CI MR fluid was prepared by dispersing 50 wt% of CI particles in silicone oil, and the CI/CoFe2O4 MR fluid was prepared by adding 0.1 wt% of CoFe2O4 nanoparticles to the CI MR fluid. The MR characteristics of both MR fluids were tested via a rotational rheometer at various magnetic field strengths. The CI/CoFe2O4 MR fluid showed enhanced MR characteristics with higher yield stress, shear viscosity, and dynamic modulus than that of the CI MR fluid. Furthermore, the dispersion stability of both MR fluids were also investigated via a Turbiscan optical analyzer system, and these results showed that the sedimentation ratio after 24 h had improved by about 21%.
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microcrystalline cellulose added Carbonyl Iron suspension and its magnetorheology
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2017Co-Authors: Dong Hun Bae, Hyoung Jin Choi, Kisuk Choi, Jaedo Nam, Md Sakinul Islam, Nhol KaoAbstract:Abstract Although Carbonyl Iron (CI)-based magnetorheological (MR) fluids have a wide range of applications with their magnetized and demagnetized properties in addition to their appropriate size, the large density difference between the CI particles and medium oil hinder their redispersion and operation. Microcrystalline cellulose (MCC) particles, fabricated from rice husk, were introduced as an additive for CI-based MR fluids to improve the dispersion stability and sedimentation problem of pure CI based MR fluid in this study. The rheological properties of two MR fluids with and without MCC additive were compared under an external magnetic field strength using a rotational rheometer. At zero magnetic field, the shear viscosity of the CI-MCC based MR fluid was higher than that of pure CI. On the other hand, after applying the magnetic field, the shear viscosity of pure CI based MR fluid was slightly higher than that of the CI/MCC-based MR fluid. The Turbiscan data also revealed improvement of the sedimentation properties of the CI based MR fluid.
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modified silane coated Carbonyl Iron natural rubber composite elastomer and its magnetorheological performance
Composite Structures, 2017Co-Authors: Seung Hyuk Kwon, Hyoung Jin Choi, Jae Heum Jung, Young Gil KimAbstract:Abstract To improve the dispersion of Carbonyl Iron (CI) particles in a rubbery medium, CI particles were pretreated with (3-aminopropyl) triethoxy silane (APTES), and processed with natural rubber for the fabrication of magnetorheological (MR) elastomers. In particular, for its anisotropic state, the MR elastomer sample was cured under a specific magnetic field to align the magnetic particles in the direction of the magnetic field. Scanning electron microscopy and mapping analysis were carried out to observe not only the coating of the CI particles with APTES but also the anisotropic state and the dispersion of CI particles in the MR elastomers. Viscoelastic experiments, such as strain amplitude and frequency sweep tests, were measured using a rotational rheometer under a range of applied magnetic fields. The CI/APTES-based MR elastomers demonstrated superior MR properties to the CI-based MR elastomer according to the rheological tests.
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magnetic Carbonyl Iron natural rubber composite elastomer and its magnetorheology
Composite Structures, 2016Co-Authors: Hyo Seung Jung, Hyoung Jin Choi, Seung Hyuk Kwon, Jae Heum Jung, Young Gil KimAbstract:Abstract Magnetorheological (MR) elastomer composites, consisting of natural rubber and Carbonyl Iron (CI), were fabricated in two different forms of isotropic and anisotropic states. In the case of the anisotropic MR elastomer sample, it was cured under an applied external magnetic field. Therefore, the dispersed CI particles were pre-aligned in the direction of the applied magnetic field. To confirm the arrangement of CI particles in the elastomer composite, a mapping method by scanning electron microscopy was used. The MR effect of these MR elastomer samples was measured using a rotational rheometer under an external magnetic field. The results showed that as the magnetic field strength increases, the storage moduli increased depending on the angular frequency at a constant shear strain. Higher MR performance from both the viscoelastic characteristics and MR efficiency were also observed for the anisotropic MR elastomer compared to the isotropic MR elastomer.
Wancheng Zhou - One of the best experts on this subject based on the ideXlab platform.
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highly oriented flake Carbonyl Iron carbon fiber composite as thin thickness and wide bandwidth microwave absorber
Journal of Alloys and Compounds, 2018Co-Authors: Dandan Min, Fa Luo, Yuchang Qing, Wancheng Zhou, Dongmei ZhuAbstract:Abstract Oriented flake Carbonyl Iron/carbon fibers (FCI/CF) composite with enhanced microwave absorption properties were prepared. The effects of orientation, the addition of CF, and the orientation direction of CF on the microwave absorption properties were investigated, respectively. Compared with the un-oriented FCI composites, higher permeability was obtained due to the FCI orientation. Anisotropic electrical properties of FCI/CF composite were achieved by changing the arranged orientation of CF. A novel double-layer microwave absorber by combining FCI/CF absorbers with different orientation of CF was designed to achieve absorbers with wide absorption band and optimal microwave absorption. The calculated absorption properties indicated that wider absorption bandwidth and thinner thickness were obtained by the single-layer oriented composites, and the absorption properties were further enhanced by the double-layer composites. The double-layer FCI/CF composites show a wider absorption frequency range of 12.0 GHz from 6 to 18 GHz with reflection loss (RL) below −5 dB at thickness of 0.8 mm.
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graphene nanosheet and flake Carbonyl Iron particle filled epoxy silicone composites as thin thickness and wide bandwidth microwave absorber
Carbon, 2015Co-Authors: Yuchang Qing, Y H Zhou, Wancheng ZhouAbstract:Abstract An epoxy–silicone matrix filled with both graphene nanosheets (GNs) and flake Carbonyl Iron (FCI) particles was prepared, and the influence of GNs and/or FCI particle content on the electromagnetic and microwave-absorbing properties was investigated in the frequency range of 2–18 GHz. Thin–thickness, broadband absorption microwave absorbers with homogeneously dispersed GNs and FCI particles were obtained. The values and frequency dependencies of the electromagnetic properties of such absorbers can be adjusted by simply changing the content of GNs and/or FCI particles. These changes led to an apparent improvement of impedance matching and then significantly improved the microwave absorptions. Reflection loss values exceeding −6 dB (>74.9% absorption) can be obtained in the frequency range of 5.4–18 GHz with a thickness of 0.9 mm.
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electromagnetic property of sio2 coated Carbonyl Iron polyimide composites as heat resistant microwave absorbing materials
Journal of Magnetism and Magnetic Materials, 2015Co-Authors: H. P. Wang, Wancheng ZhouAbstract:Abstract Heat resistant microwave absorbing materials were prepared by compression molding method, using polyimide resin as matrix and SiO2 coated Carbonyl Iron (CI) as filler. The SiO2 coated CI particles were prepared by Stober process. The microwave absorbing properties and the effect of heat treatment on the electromagnetic properties of SiO2 coated CI/polyimide composites were investigated. When the content of SiO2 coated CI is 60 wt%, the value of minimum reflection loss decreases from −25 dB to −33 dB with the thickness increases from 1.5 mm to 2.1 mm. According to the thermal-gravimetric analyses (TGA) curves, the polyimide matrix can be used at 300 °C for long time. The complex permittivity of the composites slightly increases while the complex permeability almost keeps constant after heat treatment at 300 °C for 10 h, which indicating that the composites can be used at elevated temperature as microwave absorbing materials at the same time have good heat resistance and microwave absorption.
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optimization of electromagnetic matching of Carbonyl Iron batio3 composites for microwave absorption
Journal of Magnetism and Magnetic Materials, 2011Co-Authors: Yuchang Qing, Wancheng ZhouAbstract:Abstract Microwave absorbing materials filled with BaTiO 3 and Carbonyl Iron (CI) particles with various weight fractions (BaTiO 3 /CI particles=100/0 to 0/100) are investigated. The dielectric and magnetic properties of the absorbers can be tuned by changing the weight ratio of BaTiO 3 /CI particles in the frequency range of 2–18 GHz. Numerical simulations are also performed to design a single-layer and double-layer absorber. The minimum reflection loss of the composite filled with 20 wt% BaTiO 3 and 60 wt% CI particles at 2.0 mm thickness can be reached to −42 dB at 4.1 GHz. With the weight ratio of CI particles in the composite increased, the microwave absorption peak shifted to the lower frequency region. By using a double-layer absorber structure, the microwave absorption performance of the absorber is enhanced. The result shows that the total thickness of the absorber can be reduced below 1.4 mm by using a matching layer filled with 50 wt% BaTiO 3 , and an absorption layer filled with 60 wt% BaTiO 3 and 20 wt% CI particles, whereas the reflection loss below −10 dB can be obtained in the frequency range of 10.8–14.8 GHz and the minimum reflection loss of −59 dB can be obtained at 12.5 GHz.
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epoxy silicone filled with multi walled carbon nanotubes and Carbonyl Iron particles as a microwave absorber
Carbon, 2010Co-Authors: Yuchang Qing, Wancheng ZhouAbstract:Abstract Microwave absorbing composites with epoxy-silicone as matrix and both multi-walled carbon nanotubes (MWCNTs) and Carbonyl Iron (CI) particles as absorbers were prepared, and their electromagnetic and microwave absorbing properties were investigated in the frequency range of 2–18 GHz. The microstructures of the composites show a uniform dispersion of the MWCNTs and CI particles in the matrix. The complex permittivity of the composites increased with increasing MWCNT content. A double resonance behavior of the complex permeability has been observed. One is due to the domain wall motion at about 7.5 GHz and the other is due to spin rotation at about 13.5 GHz. Reflection loss values exceeding −5 dB can be obtained in the frequency range of 10.4–18, 4.4–18 and 2–18 GHz, when the composite thickness is 0.5, 1 and 1.5 mm, respectively. A minimum reflection loss of −16.9 dB at 10.5 GHz and a bandwidth over the frequency range of 3.4–18 GHz with reflection loss below −10 dB can obtained for a composite filled with 0.5 vol% MWCNT and 50 vol% CI particles.
Yuchang Qing - One of the best experts on this subject based on the ideXlab platform.
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highly oriented flake Carbonyl Iron carbon fiber composite as thin thickness and wide bandwidth microwave absorber
Journal of Alloys and Compounds, 2018Co-Authors: Dandan Min, Fa Luo, Yuchang Qing, Wancheng Zhou, Dongmei ZhuAbstract:Abstract Oriented flake Carbonyl Iron/carbon fibers (FCI/CF) composite with enhanced microwave absorption properties were prepared. The effects of orientation, the addition of CF, and the orientation direction of CF on the microwave absorption properties were investigated, respectively. Compared with the un-oriented FCI composites, higher permeability was obtained due to the FCI orientation. Anisotropic electrical properties of FCI/CF composite were achieved by changing the arranged orientation of CF. A novel double-layer microwave absorber by combining FCI/CF absorbers with different orientation of CF was designed to achieve absorbers with wide absorption band and optimal microwave absorption. The calculated absorption properties indicated that wider absorption bandwidth and thinner thickness were obtained by the single-layer oriented composites, and the absorption properties were further enhanced by the double-layer composites. The double-layer FCI/CF composites show a wider absorption frequency range of 12.0 GHz from 6 to 18 GHz with reflection loss (RL) below −5 dB at thickness of 0.8 mm.
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graphene nanosheet and flake Carbonyl Iron particle filled epoxy silicone composites as thin thickness and wide bandwidth microwave absorber
Carbon, 2015Co-Authors: Yuchang Qing, Y H Zhou, Wancheng ZhouAbstract:Abstract An epoxy–silicone matrix filled with both graphene nanosheets (GNs) and flake Carbonyl Iron (FCI) particles was prepared, and the influence of GNs and/or FCI particle content on the electromagnetic and microwave-absorbing properties was investigated in the frequency range of 2–18 GHz. Thin–thickness, broadband absorption microwave absorbers with homogeneously dispersed GNs and FCI particles were obtained. The values and frequency dependencies of the electromagnetic properties of such absorbers can be adjusted by simply changing the content of GNs and/or FCI particles. These changes led to an apparent improvement of impedance matching and then significantly improved the microwave absorptions. Reflection loss values exceeding −6 dB (>74.9% absorption) can be obtained in the frequency range of 5.4–18 GHz with a thickness of 0.9 mm.
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optimization of electromagnetic matching of Carbonyl Iron batio3 composites for microwave absorption
Journal of Magnetism and Magnetic Materials, 2011Co-Authors: Yuchang Qing, Wancheng ZhouAbstract:Abstract Microwave absorbing materials filled with BaTiO 3 and Carbonyl Iron (CI) particles with various weight fractions (BaTiO 3 /CI particles=100/0 to 0/100) are investigated. The dielectric and magnetic properties of the absorbers can be tuned by changing the weight ratio of BaTiO 3 /CI particles in the frequency range of 2–18 GHz. Numerical simulations are also performed to design a single-layer and double-layer absorber. The minimum reflection loss of the composite filled with 20 wt% BaTiO 3 and 60 wt% CI particles at 2.0 mm thickness can be reached to −42 dB at 4.1 GHz. With the weight ratio of CI particles in the composite increased, the microwave absorption peak shifted to the lower frequency region. By using a double-layer absorber structure, the microwave absorption performance of the absorber is enhanced. The result shows that the total thickness of the absorber can be reduced below 1.4 mm by using a matching layer filled with 50 wt% BaTiO 3 , and an absorption layer filled with 60 wt% BaTiO 3 and 20 wt% CI particles, whereas the reflection loss below −10 dB can be obtained in the frequency range of 10.8–14.8 GHz and the minimum reflection loss of −59 dB can be obtained at 12.5 GHz.
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epoxy silicone filled with multi walled carbon nanotubes and Carbonyl Iron particles as a microwave absorber
Carbon, 2010Co-Authors: Yuchang Qing, Wancheng ZhouAbstract:Abstract Microwave absorbing composites with epoxy-silicone as matrix and both multi-walled carbon nanotubes (MWCNTs) and Carbonyl Iron (CI) particles as absorbers were prepared, and their electromagnetic and microwave absorbing properties were investigated in the frequency range of 2–18 GHz. The microstructures of the composites show a uniform dispersion of the MWCNTs and CI particles in the matrix. The complex permittivity of the composites increased with increasing MWCNT content. A double resonance behavior of the complex permeability has been observed. One is due to the domain wall motion at about 7.5 GHz and the other is due to spin rotation at about 13.5 GHz. Reflection loss values exceeding −5 dB can be obtained in the frequency range of 10.4–18, 4.4–18 and 2–18 GHz, when the composite thickness is 0.5, 1 and 1.5 mm, respectively. A minimum reflection loss of −16.9 dB at 10.5 GHz and a bandwidth over the frequency range of 3.4–18 GHz with reflection loss below −10 dB can obtained for a composite filled with 0.5 vol% MWCNT and 50 vol% CI particles.
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electromagnetic and microwave absorption properties of Carbonyl Iron and carbon fiber filled epoxy silicone resin coatings
Applied Physics A, 2010Co-Authors: Yuchang Qing, S Jia, Fa Luo, W C Zhou, Dongmei ZhuAbstract:The microwave electromagnetic properties of Carbonyl-Iron particles as magnetic absorber and carbon fiber as conductive absorber filled insulating epoxy/silicone resin coatings were investigated. The complex permittivity of the coatings increased while the complex permeability remained almost constant in the frequency range of 2–18 GHz, when the carbon fiber content was increased and the Carbonyl-Iron content kept constant. The minimum reflection loss of the coatings shifted to the lower frequency region by increasing the carbon fiber content or coating thickness. When the content of Carbonyl Iron was 65 wt% and carbon fiber was 2 wt%, the reflection loss below −10 dB can obtain in the frequency range of 8–18 GHz with coating thickness being 1 mm.
Dongmei Zhu - One of the best experts on this subject based on the ideXlab platform.
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highly oriented flake Carbonyl Iron carbon fiber composite as thin thickness and wide bandwidth microwave absorber
Journal of Alloys and Compounds, 2018Co-Authors: Dandan Min, Fa Luo, Yuchang Qing, Wancheng Zhou, Dongmei ZhuAbstract:Abstract Oriented flake Carbonyl Iron/carbon fibers (FCI/CF) composite with enhanced microwave absorption properties were prepared. The effects of orientation, the addition of CF, and the orientation direction of CF on the microwave absorption properties were investigated, respectively. Compared with the un-oriented FCI composites, higher permeability was obtained due to the FCI orientation. Anisotropic electrical properties of FCI/CF composite were achieved by changing the arranged orientation of CF. A novel double-layer microwave absorber by combining FCI/CF absorbers with different orientation of CF was designed to achieve absorbers with wide absorption band and optimal microwave absorption. The calculated absorption properties indicated that wider absorption bandwidth and thinner thickness were obtained by the single-layer oriented composites, and the absorption properties were further enhanced by the double-layer composites. The double-layer FCI/CF composites show a wider absorption frequency range of 12.0 GHz from 6 to 18 GHz with reflection loss (RL) below −5 dB at thickness of 0.8 mm.
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electromagnetic and microwave absorption properties of Carbonyl Iron and carbon fiber filled epoxy silicone resin coatings
Applied Physics A, 2010Co-Authors: Yuchang Qing, S Jia, Fa Luo, W C Zhou, Dongmei ZhuAbstract:The microwave electromagnetic properties of Carbonyl-Iron particles as magnetic absorber and carbon fiber as conductive absorber filled insulating epoxy/silicone resin coatings were investigated. The complex permittivity of the coatings increased while the complex permeability remained almost constant in the frequency range of 2–18 GHz, when the carbon fiber content was increased and the Carbonyl-Iron content kept constant. The minimum reflection loss of the coatings shifted to the lower frequency region by increasing the carbon fiber content or coating thickness. When the content of Carbonyl Iron was 65 wt% and carbon fiber was 2 wt%, the reflection loss below −10 dB can obtain in the frequency range of 8–18 GHz with coating thickness being 1 mm.
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electroless plating preparation and microwave electromagnetic properties of ni coated Carbonyl Iron particle epoxy coatings
Physica B-condensed Matter, 2010Co-Authors: S Jia, Fa Luo, Yuchang Qing, Wancheng Zhou, Dongmei ZhuAbstract:The morphology, composition, electromagnetic and microwave absorbing properties of the electroless Ni plated Carbonyl Iron (CI) particles were characterized using electron scanning microscope (SEM), energy dispersive spectrometer (EDS) and microwave network analyzer. The SEM and EDS results indicate that the CI particles were coated with uniform Ni coating. After the CI particles were coated with Ni, the real part of complex permittivity of the Ni-coated CI particles decreased while the complex permeability and the imaginary part of complex permittivity kept almost constant. The complex permittivity and complex permeability of the Ni-coated CI particles filled epoxy coatings increased with increase in weight content of Ni-coated CI particles. Compared with the raw CI particles/epoxy coatings with the same coating thickness and particles content, the Ni-coated CI particles/epoxy coatings possessed higher microwave absorption in the X-band and the microwave absorbing peak shifted to a higher frequency range.
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microwave electromagnetic properties of Carbonyl Iron particles and si c n nano powder filled epoxy silicone coating
Physica B-condensed Matter, 2010Co-Authors: Yuchang Qing, Fa Luo, Wancheng Zhou, Dongmei ZhuAbstract:Abstract The electromagnetic characteristics of Carbonyl Iron particles and Si/C/N nano-powder filled epoxy-silicone coatings were studied. The reflection loss of the coatings exceeds −10 dB at 8–18 GHz and −9 dB at 2–18 GHz when the coating thickness is 1 and 3 mm, respectively. The dielectric and magnetic absorbers filled coatings possess excellent microwave absorption, which could be attributed to the proper incorporate of the multi-polarization mechanisms as well as strong natural resonance. It is feasible to develop the thin and wideband microwave absorbing coatings using Carbonyl Iron particles and Si/C/N nano-powder.
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dielectric properties of carbon black and Carbonyl Iron filled epoxy silicone resin coating
Journal of Materials Science, 2010Co-Authors: Yuchang Qing, S Jia, Fa Luo, Wancheng Zhou, Dongmei ZhuAbstract:The dielectric properties of epoxy–silicone resin coatings containing carbon black (CB) and Carbonyl Iron (CI) particles as a function of frequency (2–18 GHz) and the CB volume content (0.2–1%) have been investigated. The complex permittivity of the coatings increased with increasing CB content, which mainly attributed to the interfacial polarization at the CB/resin/CI particles interfaces. The complex permittivity also decreased rapidly with increasing frequency in the low frequency range while decreased slowly in the high frequency range. The changes of dielectric properties with frequency and the CB volume content were discussed using the power-law decay and the concept of interfacial polarization.
Tao Wang - One of the best experts on this subject based on the ideXlab platform.
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Greatly enhanced microwave absorbing properties of planar anisotropy Carbonyl-Iron particle composites
Journal of Magnetism and Magnetic Materials, 2015Co-Authors: Liang Qiao, Tao Wang, Rui Han, Liyun TangAbstract:Abstract This paper investigates the high permeability and high resonance frequency characteristics of Carbonyl-Iron particle composites at microwave range. It finds that the key factor to keep both high microwave absorbing characteristics is the planar anisotropy. The effective permeability of planar anisotropy Carbonyl-Iron particles/nonmagnetic matrix composition in high frequency is measured and calculated. In contrast to the sphere shaped particles with no planar anisotropy, the permeability and resonance frequency of flake particles are greatly enhanced by introducing the planar anisotropy, and the permeability can be further enhanced by using a rotational orientation method to get higher planar anisotropy. As the use of the planar anisotropy, the flake soft magnetic particles increase the natural resonant frequencies so as to lead the higher real part and the imaginary part of the permeability in a broadband range. The resonance peak of flake particles is simulated by using the combination of the Landau–Lifshitz–Gilbert equation and Bruggeman’s effective medium theory, considering the correction of shape factor. Our theory simulation agrees well with the experimental data.
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reflection loss mechanism of single layer absorber for flake shaped Carbonyl Iron particle composite
Journal of Applied Physics, 2012Co-Authors: Tao Wang, Liang Qiao, Fashen LiAbstract:The reflection loss (RL) properties including the frequency, intensity, and bandwidth of absorption peaks for the flake-shaped Carbonyl-Iron particle/paraffin composite were investigated in detail. By measuring the reflection coefficient of the composite without (S11-OPEN) and with (S11-SHORT) a backed metal plate, the origin of the RL peak was directly verified. The separated electromagnetic wave energy reflected at the air-absorber interface and the absorber-metal plate interface was achieved from S11-OPEN and S11-SHORT parameters, and they were used to explain the intensity variation of the RL peak. The bandwidth of the RL peak was also deduced from viewpoint of interface reflection waves. The calculated bandwidth from the derived formula agreed well with the experimental data.
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complex permeability and microwave absorbing properties of planar anisotropy Carbonyl Iron ni0 5zn0 5fe2o4 composite in quasimicrowave band
Materials Chemistry and Physics, 2012Co-Authors: Rui Han, Tao Wang, Lu-qian Gong, Liang QiaoAbstract:Abstract Planar anisotropy Carbonyl-Iron (PACI)/Ni 0.5 Zn 0.5 Fe 2 O 4 composite as absorbent filler in quasimicrowave band has been synthesized via ball-milling technique and solvothermal method. The effective permeability of the composite was measured and calculated. The result indicates that the magnetic loss in the composite is mainly caused by the natural resonance. Compared with the uncoated PACI particles, the permittivity of the composite decreased dramatically, and hence a dramatic enhancement of reflection loss (RL) was obtained in quasimicrowave band. This result indicates that our PACI/ferrite composite can be used as potential microwave absorbers in quasimicrowave band for its novel microwave properties.
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investigation on peak frequency of the microwave absorption for Carbonyl Iron epoxy resin composite
Journal of Magnetism and Magnetic Materials, 2011Co-Authors: Bochong Wang, Tao Wang, Yong Yang, Fashen LiAbstract:Abstract Microwave absorbing characteristics of Carbonyl Iron/epoxy resin composite with various volume concentrations were investigated in 0.1–18 GHz. According to the electromagnetic parameters and thicknesses of the sample, numerical calculation and experiment have demonstrated that the frequency dependence of the microwave absorption comply with the quarter-wavelength (λ/4) matching model that may explain not only the peak frequency but also the number of the peaks. It implies that the quarter-wavelength condition can be successfully applied to understand and predict the peak frequency of the microwave absorption for ferromagnetic metal-based composites.
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Microwave complex permeability of planar anisotropy Carbonyl-Iron particles
Journal of Alloys and Compounds, 2011Co-Authors: Rui Han, Liang Qiao, Tao WangAbstract:Abstract Planar anisotropy Carbonyl-Iron (PACI) particles were prepared from sphere-shaped Carbonyl-Iron (SSCI) materials by a simple ball milling technique. The frequency-dependent complex permeability of paraffin composites with 50% volume concentration of particles has been investigated in 0.1–18 GHz frequency range. The as-milled PACI composites show a dramatic enhancement of complex permeability and a higher resonance frequency compared with SSCI composite. This is due to the PACI particles, which have an easy magnetization plane and a thickness smaller than their skin depth, suppressing the eddy current effects. Furthermore, the complex permeability is further improved after the PACI composite was rotationally orientated in an external magnetic field. The real permeability of oriented PACI composite reaches a large value of approximate 10.5 at 0.1 GHz, and the resonance frequency shifts to a higher frequency range.