Facile synthesis of Fe-6.5wt%Si/SiO2 soft magnetic composites as an efficient soft magnetic composite material at medium and high frequencies

Wu, Zhaoyang; Jiang, Zhenfei; Fan, Xiaoliang; Zhou, Libo; Wang, W.L.; Xu, Kun

doi:10.1016/j.jallcom.2018.01.307

Cited by 61 publications

(20 citation statements)

References 30 publications

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“…All of these techniques proved to be expensive, industrially challenging and of limited practical application. Several papers report about sintered soft magnetic cores (e.g., [ 11 , 37 , 38 ]) with insulating materials between alloy particles (such as SiO 2 [ 37 ] and Al 2 O 3 [ 38 ]). Such insulators act in reducing the generation of inter-particle eddy current.…”

Section: Introductionmentioning

confidence: 99%

Properties of Additively Manufactured Electric Steel Powder Cores with Increased Si Content

et al. 2021

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In this paper, the best laser powder bed fusion (L-PBF) printing conditions for FeSi steels with two different Si content (3.0% and 6.5%) are defined. Results show very strict processing window parameters, following a lack of fusion porosity at low specific energy values and keyhole porosity in correspondence with high specific energy values. The obtained microstructure consists of grains with epitaxial growth starting from the grains already solidified in the underling layer. This allows the continuous growth of the columnar grains, directed parallel to the built direction of the component. The magnetic behaviour of FeSi6.5 samples, although the performances found do not still fully reach those of the best commercial electrical steels (used to manufacture magnetic cores of electrical machines and other similar magnetic components), appears to be quite promising. An improvement of the printing process to obtain thin sheets with increased Si content, less than 0.5 mm thick, with accurate geometry and robust structures, can result to an interesting technology for specific application where complex geometries and sophisticated shapes are required, avoiding mechanical machining processes for electrical steel with high silicon content.

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Section: Introductionmentioning

confidence: 99%

Properties of Additively Manufactured Electric Steel Powder Cores with Increased Si Content

et al. 2021

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“…Moreover, the coating system based on SiO 2 represents a solution to the problem caused by organic layers, which decompose at high temperatures, making annealing and heat treatments very limited and impossible at temperatures over 500 • C [33][34][35][36]. It also ensures high resistivity and limitation of conducting paths, reducing eddy currents, confining them inside the particles and obtaining limited core losses [28,33,37,38].…”

Section: Silicamentioning

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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“…The layers are of organic or inorganic origin [7][8][9][10]. In the case of inorganic insulating materials, different solutions are proposed and adopted based on silica, silicon particles, ferrite particles, amorphous powder, and metal oxides (Al 2 O 3 , MnO, TiO 2 , and others) [11][12][13][14][15][16][17][18][19]. Some of these solutions brought promising results but are still under study and development, mainly to resolve and improve mechanical performance.…”

Section: Introductionmentioning

confidence: 99%

Rapid Characterization Method for SMC Materials for a Preliminary Selection

et al. 2021

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In electrical machines, laminated steels are commonly adopted as soft magnetic materials, while for permanent magnets, sintered ferrites and NdFeB are the most common solutions. On the other hand, the growing demand for volume reduction with the increment of efficiency leads to the necessity of exploring other magnetic materials able to face the challenge better than the traditional ones. Bonded magnets have been used to replace sintered magnets, obtaining a better use of space and particular magnetic properties. Instead, for the magnetic circuit, Soft Magnetic Composites (SMC) allow realizing very complex magnetic design (3D path for flux) with iron loss reduction at medium-high frequencies, especially for the eddy currents loss contribution. On the other hand, SMC materials have such drawbacks as low mechanical properties and high hysteresis losses. For this reason, in this work, different studies considering several variables have been carried out. SMCs were produced through a moulding process; inorganic and organic layers to cover ferromagnetic particles were used, adopting different coating processes. Particular tests have been performed for a quicker and more indicative overview of the materials obtained. The single sheet tester (SST) is easier than traditional toroidal methods; on the other hand, the multiplicity of variables affects the SMC materials and their process. For this reason, coercivity and conductibility tests permit rapid measurement and provide a direct classification of the produced SMCs, providing the main information needed to select suitable materials. Results highlighted that choosing the more appropriate SMC material is possible after using these simple preliminary tests. After these tests, it was possible to argue that with 0.2 wt% of phenolic resin as the organic layer (and compaction pressure of 800 MPa), it is possible to produce a good SMC. On the other hand, the SMC with 0.2 wt% of epoxy resin (and compaction pressure of 800 MPa) gives a minor coercivity value. Additionally, despite the SMC with the inorganic layer, 0.2 wt% of nano-ferrites showing the best coercivity values (specifically for vacuum treatment at 600 °C), their resistivity was unsatisfactory.

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Facile synthesis of Fe-6.5wt%Si/SiO2 soft magnetic composites as an efficient soft magnetic composite material at medium and high frequencies

Cited by 61 publications

References 30 publications

Properties of Additively Manufactured Electric Steel Powder Cores with Increased Si Content

Properties of Additively Manufactured Electric Steel Powder Cores with Increased Si Content

Recent Advances in Multi-Functional Coatings for Soft Magnetic Composites

Rapid Characterization Method for SMC Materials for a Preliminary Selection

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