Improving Powder Magnetic Core Properties via Application of Thin, Insulating Silica-Nanosheet Layers on Iron Powder Particles

Abstract

A thin, insulating layer with high electrical resistivity is vital to achieving high performance of powder magnetic cores. Using layer-by-layer deposition of silica nanosheets or colloidal silica over insulating layers composed of strontium phosphate and boron oxide, we succeeded in fabricating insulating layers with high electrical resistivity on iron powder particles, which were subsequently used to prepare toroidal cores. The compact density of these cores decreased after coating with colloidal silica due to the substantial increase in the volume, causing the magnetic flux density to deteriorate. Coating with silica nanosheets, on the other hand, resulted in a higher electrical resistivity and a good balance between high magnetic flux density and low iron loss due to the thinner silica layers. Transmission electron microscopy images showed that the thickness of the colloidal silica coating was about 700 nm, while that of the silica nanosheet coating was 30 nm. There was one drawback to using silica nanosheets, namely a deterioration in the core mechanical strength. Nevertheless, the silica nanosheet coating resulted in nanoscale-thick silica layers that are favorable for enhancing the electrical resistivity.

Silica and carbon decorated silica nanosheet impact on primary human immune cells

“…79 NS. The spectrum of Si 2p consisting of two peaks can be attributed to the C-Si bonding, located at the binding energy of about~103.053 eV and SiO 2 located at the binding energy of about~103.998 [48,49]. The spectrum of C1 s revealed that the amorphous carbon from C/SiO 2 NS sample represent the two possible bonds of carbon C O (~287.6 eV) with atomic percentage of 74.49% and C-Si (~283.3) with atomic percentage of 24.51%, respectively [73].…”

“…Even though, graphene have been used extensively as adsorbent for many biomedical applications due to its unique properties and apparent biocompatibility [38][39][40][41], graphene has poor hydrophilicity that often requires the surface to be modified with hydrophilic moieties prior to its application [42][43][44]. Thus, mesoporous graphene-like multilayer silica nanosheets are emerging as an attractive alternate material for biomedical applications due to their unique and desirable features, such as high surface area, narrow size distribution, uniform dispersion, chemical stability, hydrophilicity, biocompatibility and high selectivity towards many molecules like peptides [12,22,[45][46][47][48][49][50].…”

Diminuição das Perdas Magnéticas em Materiais Magnéticos Macios (SMC) composto por partícula de ferro com fina camada de revestimento de fosfato e sua eficiência em motores elétricos quando aplicado a um campo magnético de baixa frequência. / Reduction of Magnetic Losses in Soft Magnetic Materials (SMC) composed of an iron particle with a thin layer of phosphate coating and its efficiency in electric motors when applied to a low frequency magnetic field.

“…A ilustração da Figura 2.a apresenta uma partícula de ferro sendo recoberta por particulados de fosfato de estrôncio e óxido bórico. Já na Figura 2.b é possível observar o surgimento de uma fina camada de dióxido de silício recobrindo a partícula de ferro (ISHIZAKI et al, 2017). A utilização nano-filmes de sílica ou sílica coloidal sobre camadas isolantes compostas por fosfato de estrôncio e óxido bórico, de forma a conseguir camadas isolantes em partículas de ferro em pó com mais alta resistividade elétrica.…”

“…Da mesma forma, diferentes tipos de recobrimentos podem ser aplicados sobre a partículas magnéticas para formar a camada isolante, sendo divididas em camadas orgânicas e inorgânicas, metálicas e não metálicas. Camadas isolantes tratadas com ácido fosfórico (H3PO4) são descritas nos trabalhos (CHEN et al, 2020(CHEN et al, , 2019ISHIZAKI et al, 2017;MAEDA et al, 2010;XIA et al, 2019;ZHOU YE;BJORN SKARMAN, 2012), bem como a adição de algum tipo de óxido na solução (um isolante de óxido pode ser usado, além de fosfato de ferro, fosfato de manganês, fosfato de zinco, fosfato de cálcio, fosfato de alumínio, óxido de silício, óxido de alumínio), tal como óxido de titânio, ou óxido de zircônio (SOARES; ALVES, 2021).…”

Iron Powders from Steel Industry by-products

“…The applications of iron powders are branched into various areas like powder metallurgy parts, 19) welding electrodes, magnetic materials, 20,21,72) electrochemical parts, 22) alkaline batteries, [23][24][25][26][27][28] food fortification, 29) environmental remediation, [30][31][32] industrial filters and purifies, 33) etc. Extremely modern and futuristic application of iron powders is targeted to use them as clean recyclable metal fuel.…”