Effect of annealing on magnetic properties of Fe/Fe3O4 soft magnetic composites prepared by in-situ oxidation and hydrogen reduction methods

Qian, Liwei; Peng, Jingguang; Xiang, Zhen; Pan, Yifan; Lü, Wei

doi:10.1016/j.jallcom.2018.11.184

Cited by 75 publications

(16 citation statements)

References 24 publications

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“…Different ferrites can be adopted for the coating process: Ni-Zn ferrite, Ni ferrite, Mn-Zn ferrite, Co ferrite, et cetera [67]. The more common iron oxides, such as hematite Fe 2 O 3 [68,69], magnetite Fe 3 O 4 [70][71][72][73][74], hematite α-Fe 2 O 3 [75], and maghemite γ-Fe 2 O 3 [74,76], are obtained in situ and/or added in the mixture to obtain the inorganic SMC layer. However, in some cases, their antiferromagnetic behavior can considerably decrease the permeability [71].…”

Section: Ferritesmentioning

confidence: 99%

Recent Advances in Multi-Functional Coatings for Soft Magnetic Composites

et al. 2021

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During the past 50 years, the aim to reduce the eddy current losses in magnetic cores to a minimum led to the formulation of new materials starting from electrically insulated iron powders, today called Soft Magnetic Composites (SMC). Nowadays, this promising branch of materials is still held back by the mandatory tradeoff between energetic, electrical, magnetic, and mechanical performances. In most cases, the research activity focuses on the deposition of an insulating/binding layer, being one of the critical points in optimizing the final composite. This insulation usually is achieved by either inorganic or organic layer constituents. The main difference is the temperature limit since most inorganic materials typically withstand higher treatment temperatures. As a result, the literature shows many materials and process approaches, each one designed to meet a specific application. The present work summarizes the recent advances in state of the art, analyzing the relationship among material compositions and magnetic and mechanical properties. Each coating shows its own processing sets, which vary from simple mechanical mixing to advanced chemical methods to metallurgical treatments. From state of the art, Aluminum coatings are characterized by higher current losses and low mechanical properties. In contrast, higher mechanical properties are obtained by adopting Silicon coatings. The phosphates coatings show the best-balanced overall properties. Each coating type was thoroughly investigated and then compared with the literature background highlighting. The present paper thus represents a critical overview of the topic that could serve as a starting point for the design and development of new and high-performing coating solutions for SMCs. However, global research activity continuously refines the recipes, introducing new layer materials. The following steps and advances will determine whetherthese materials breakthrough in the market.

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Section: Ferritesmentioning

confidence: 99%

Recent Advances in Multi-Functional Coatings for Soft Magnetic Composites

et al. 2021

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“…However, the total core loss factor almost doubles when the annealing temperature is 700°C. It could be known from the equation (4) that the hysteresis loss coefficient is a constant and the eddy current loss coefficient is a liner function of frequency [24], therefore the eddy current loss coefficient (K 2 ) and the hysteresis loss coefficient (K 1 ) could be obtained by calculating the slope for each line and deriving the line to a frequency of zero respectively. Figure 8 decipicts the hysteresis loss coefficient and the eddy current loss coefficient of SMC core samples annealed at different temperature.…”

Section: The Effect Of the Annealing Processmentioning

confidence: 99%

Effects of compaction and heat treatment on the soft magnetic properties of iron-based soft magnetic composites

Pan

Peng²,

Qian

et al. 2020

Mater. Res. Express

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Iron-based soft magnetic composites (SMCs) are promising substitutes for laminate steels in electromagnetic applications due to their excellent magnetic properties and productivity. However, the preparation process is a key factor in deciding the magnetic performance of SMCs. In this work, the Fe-based soft magnetic composites with improved soft magnetic properties were achieved by optimizing the compaction and the annealing process. Results showed that the core-shell structure of powders which would directly have an impact on the permeability and the core loss of the SMCs could be affected by the compaction and the annealing process. In addition, the magnetic properties were enhanced by tuning the microstructure. As a result, the optimal magnetic performance of the compact with high permeability and low total core loss was obtained. The real part of the permeability of the soft magnetic composites could reach a maximal value of 336.8 and a rather low core loss of 2.5 W Kg −1 (measured at 50 mT and 5 kHz). Therefore, soft magnetic composites with enhanced magnetic properties were obtained by optimizing the powder metallurgy (PM) process in this study.

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“…The low thermal stability of traditional resin material limits the subsequent annealing treatment. Then, the introduction of inorganic substances improves the heat resistance of the insulating layer, such as SiO 2 , Al 2 O 3 , MgO, Fe 3 O 4 , phosphate coating [3,[10][11][12][13] etc. Among these coatings, phosphate coating has been widely used in the fabrication of the SMCs due to its simple preparation process, high electrical resistivity and strong adhesion to the powder surfaces [14].…”

Section: Introductionmentioning

confidence: 99%

Improved magnetic properties of iron-based soft magnetic composites with a double phosphate-SiO2 shells structure

Yuan

Sun

Tian

et al. 2021

J Mater Sci: Mater Electron

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Herein a double shells structure was proposed to overcome the drawbacks such as poor heat resistance, incomplete insulation and high core loss coating of ironbased soft magnetic composites (SMCs) with single shell structure. The surface of the iron powder was coated with a double shells structure composed of an inner phosphate coating and an outer SiO 2 coating through phosphating and hydrolysis successively. Subsequently, the effects of different SiO 2 addition amount on the microstructure of iron powder and magnetic properties of SMCs were studied. The introduction of SiO 2 in the double shells structure inhibited the decomposition and failure of phosphating layer after being annealed at a high temperature. The iron powder coated with the phosphate-SiO 2 insulating layer was still effective after annealing in a N 2 atmosphere at 570 °C, achieving the purpose of eliminating residual stress and improving magnetic properties. The optimal process parameters were set at 0.2 wt% phosphoric acid and 0.5 wt% tetraethyl orthosilicate to fabricate the phosphate-SiO 2 double shells. The iron-based SMCs presented excellent magnetic properties with B s of 1.29 T and P s of 169.2 W/kg (measured at 1 T and 1 kHz). In addition, the core loss of SMCs introduced with SiO 2 is 83% lower than that of SMCs produced by the phosphating process. This paper provides a feasible method for improving the magnetic properties of SMCs.

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Effect of annealing on magnetic properties of Fe/Fe3O4 soft magnetic composites prepared by in-situ oxidation and hydrogen reduction methods

Cited by 75 publications

References 24 publications

Recent Advances in Multi-Functional Coatings for Soft Magnetic Composites

Recent Advances in Multi-Functional Coatings for Soft Magnetic Composites

Effects of compaction and heat treatment on the soft magnetic properties of iron-based soft magnetic composites

Improved magnetic properties of iron-based soft magnetic composites with a double phosphate-SiO2 shells structure

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