Papers by Keyword: Ferrite

Abstract: This paper presents the design, development and characterization of the spinel ferrite [Mn_0.2Zn_0.8Fe₂O₄] powders and Nickel (Ni)-coated multiwall carbon nanotubes (MWNTs). A combination of Mn_0.2Zn_0.8Fe₂O₄ spinel ferrites particles and Nickel (Ni)-coated multiwall carbon nanotubes (MWNTs) were introduced into epoxy resin to be a microwave absorber. The structural characterizations and surface morphology of Mn_0.2Zn_0.8Fe₂O₄ and MWNTs were investigated by X-ray diffraction (XRD) and scanning electron microscopy respectively. The electromagnetic wave absorption characteristics of the composites have been studied in the frequency interval of 12-15GHz.The results for Mn0.2Zn0.8Fe2O4/EP, Mn_0.2Zn_0.8Fe₂O₄/MWNTs/EP and Mn_0.2Zn_0.8Fe₂O₄/Ni-coated MWNTs/EP microwave absorbers for the same thickness have been reported. It has been found that the Mn_0.2Zn_0.8Fe₂O₄/Ni-coated MWNTs/EP composites show the broadband characteristics with minimum absorption of 5 dB about 2.6 GHz and the maximum absorption of 37.05 dB at 14 GHz for a coating thickness of 2 mm. Therefore, Mn0.2Zn0.8Fe2O4/Ni-coated MWNTs/EP composites will be a suitable microwave absorptive material for 12-15GHz.

Abstract: The emphasis of this study was surface modification on MWNTs by dielectric barrier discharge plasma at atmospheric pressure. The effects of the plasma treatment on the MWNTs were characterized by SEM, XRD and FT-IR. The results show that surface of carbon nanotubes (CNTs) emerge carboxyl group, and the plasma modified CNTs by a physico chemical adsorption without structural damage. Modified CNTs/ferrite/polyimide nanocomposites, were prepared and mechanical test demonstrate the low temperature plasma treatment is an effective way to improve interfical bonding bewteen CNTs and polyimide (PI) matrix.

Abstract: In this article, the general design of external-rotor ferrite permanent magnet BLDC motor is required. Based on the principle of cost reduction, we designed and manufactured motor prototype, and simulated it with the finite element method for electromagnetic field, and had no load and load test to verify the legitimacy of motor design parameters. We made a system test of fan-driven by a prototype, and the measured data showed that the external-rotor brushless DC motor had good performance and lower cost and had the advantages for industrial production.

Abstract: In this paper, we presented two types of ferrite&si double layer substrate microstrip lines structures and derived waveguide admittance through coordinate rotation and Fourier transformation of Maxwell equations, then we analyzed its characteristics. We performed dispersion characteristic calculations on microstrip lines, discussed influence of various parameters of microstrip lines on dispersion characteristics and compared their characteristics, then we discovered parameters influence on one specific type of structure dispersion is minimum, especially on technique dimension of dielectric. It can make applications for IC fabrication.

Abstract: Anti-bacterial property is a major concern of material use in many areas, such as food industries, hospitals, and kitchenware. It is well known that Ag owns the ability to destroy the cell walls and cell membranes of bacteria to inhibit their breeding. Therefore, Ag implanted on the material surfaces is a popular process in biomedical application. Once the implanted layer is destroyed, the well-effective antibacterial property is also ceased. In order to improve the effectiveness of bacterial characteristics, adding Ag in 2205 duplex stainless steel can maintain the bacterial property for a long period of time than Ag-implanted process. 2205 duplex stainless steel possesses excellent corrosion resistance, high strength, and superior workability, owing to possess both austenite and ferrite phase. Among them, 2205 duplex stainless steel was adopted as the test material, doping various Ag contents in this study. The result reveals that Ag content increased with ferrite phase fraction increasing. It showed Ag is the stabilizer of ferrite. In addition, the solubility of Ag into Fe was extremely low and Ag particles were distributed randomly. However, polarization test was carried out to investigate the ability of corrosion resistance. The test result showed adding Ag in 2205 duplex stainless steel had obvious contribution to decrease its corrosion resistance.

Abstract: Positron annihilation technique is a well known technique to characterize the defects in a material. These defects can be identified by positron annihilation lifetime and coincidence Doppler broadening of positron annihilation radiation measurement. In this chapter we report the room temperature positron annihilation lifetime for single crystalline ZnO. From our study it is confirmed that the present crystal contains V_Zn–hydrogen complexes with low open volumes. Another important nuclear solid technique is the Mossbauer Spectroscopic technique which has been used to probe the local magnetic properties of a solid. Here we have summarized Mossbauer spectroscopic studies on ferrites.

Abstract: In order to find the reasons of that the hardness of 1Cr17Ni2 stainless steel partial components after being quenched is weakened, based on the sampling analysis on the partial components to produces the components to carry on the sampling analysis, and to compare the contrast that the maximum of the hardness of quenched material is lower than (the average value of the hardness – the standard deviation) to that the minimum is higher than (the average value of the hardness + the standard deviation), we draw an exciting conclusion. The Cr content in steel is on the high side and the Ni content is on the low side. Especially the components present low hardness after being quenched whose C content is low, and the components present high hardness after being quenched whose C content is high. The reason why components have low hardness is that the contents of the element C and Ni to making Austenite in the 1Cr17Ni2 stainless steel is low, the contents of the element Cr to making Ferrite is high, and the martensite hardness is low and the Ferritecontents is high after being quenched.

Abstract: It is shown that the discreteness of the chemical compositions of 0Cr12Mn5Ni4Mo3Al steel is large and the range of the Cr/Ni equivalent ratio is wide, which has big impact on the content and morphology of ferrite and easy to occur cracking phenomenon when bearing, based on the chemical compositions analysis of pipe sleeve on aircraft flare-less pipe joints. It can be found that the chemical compositions of cracked pipe sleeve are almost meeting the requirements, but the Cr/Ni equivalent ratio is on the high side. So it can be concluded that the fracture failure of pipe sleeve is closely related to the content, shape and distribution of δ-ferrite. Thus, the available solution of the cracking in 0Cr12Mn5Ni4Mo3Al stainless steel pipe sleeve is to reduce the Cr/Ni equivalent ratio within the permissive of nominal chemical compositions and adjust the hot working process to form the reasonable morphology and distribution of δ-ferrite.

Abstract: Blast furnace dust was used to synthesize ferrite, which could not only increase the economic value of mineral resources, but also reduce the production cost. High infrared radiation ceramic was prepared using cordierite and ferrite FeMnCuO₄ by high temperature solid state sintering method. The phase composition and the microstructure of the sample were investigated using XRD analysis and SEM. The infrared emissivity of the infrared radiation ceramic was 0.88. Ferrite and cordierite form replacement type sosoloid at high temperature, which can greatly improve the infrared radiation property of ceramic.

Abstract: One-dimensional Co_0.5Zn_0.5Fe₂O₄ nanostructures (nanofibers) with an average diameter of 154 nm were fabricated by electrospinning. These nanofibers were characterized by X–ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Magnetic hysteresis loops were measured for randomly oriented and aligned Co_0.5Zn_0.5Fe₂O₄ nanofibers, in comparison with the corresponding powder sample synthesized using the conventional sol-gel process. The differences in magnetic properties are observed between the Co_0.5Zn_0.5Fe₂O₄ nanofibers and powders, and these differences mainly arise from the grain size and morphological variations between these two materials. In determining the magnetization ease axis for the aligned Co_0.5Zn_0.5Fe₂O₄ nanofibers the shape anisotropy is slightly dominant competing with the magnetocrystalline anisotropy.