Influence of processed parameters on the magnetic properties of Fe/Fe 3 O 4 composite cores
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Influence of processed parameters on the magnetic properties of Fe/Fe3O4 composite cores Qian Zhang1, Shouguo Li1, Wei Zhang1, and Kun Peng1,2,* 1 2
College of Materials Science and Engineering, Hunan University, Changsha 410082, China Hunan Engineering Technology Research Center for Microwave Devices and Equipment, Hunan University, Changsha 410082, China
Received: 5 October 2020
ABSTRACT
Accepted: 15 November 2020
Fe powders coated with Fe3O4 insulating layers were synthesized by in-situ oxidization method, and then the Fe/Fe3O4 composite cores were prepared by a powder metallurgy procedure. The formation of Fe3O4 on the surface of Fe powders can effectively reduce the magnetic loss and enhance the high-frequency performance of magnetic cores. With the increase of pressing pressure, the permeability increased firstly and then decreased, while the magnetic loss shows the opposite law. The residual stress of the composites can be released more sufficient by increasing the annealing temperature, which leads to the increase in permeability; however, Fe3O4 will decompose into FeO when the annealing temperature rises to 570 °C, thus destroying the magnetic properties of Fe-based soft magnetic composites. The composite compressed at 800 MPa and annealed in argon at 500 °C for 2 h exhibits excellent magnetic performance, which presents high permeability (l) of 56 (1 KHz), high saturation magnetization (Ms) of 219.2 emu/g, and low magnetic loss (P) of 30.5 w/kg (20 mT, 100 kHz).
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Soft magnetic composites (SMCs) with high resistivity, high flux density, three-dimensional isotropic ferromagnetic behavior, and flexible design are generally applied to the energy applications such as motors, inductors, and computers, which have been an important subclass in the field of energy conversion [1–6]. For the past few years, iron-based powders have been widely used in low-frequency application due to their characteristics of high saturation magnetization, high permeability, and low
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https://doi.org/10.1007/s10854-020-04896-1
cost. But its low resistivity limits the development at high frequency. To acquire the composites with excellent comprehensive magnetic properties, many methods have been used to improve the electrical resistivity and then reduce the magnetic loss, and among these methods, the core–shell iron-based soft magnetic composites have attracted extensive research interest. The non-magnetic phase insulating layer such as polyamide, resin [7, 8], silica [9], alumina [10], TiO2 [11], and magnesia [12] is usually added to the SMCs by mechanical mixing [13], Sol-gel [14] method. It can improve the electrical resistivity
J Mater Sci: Mater Electron
and reduce the magnetic loss; however, it also results in a significant decrease in the saturation magnetization and permeability. To overcome these defects, ferrite such as MnZn, NiZn, and Fe3O4 [15–21] have been used to replace non-ma
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