Nacre‐Inspired, Efficient, and Multifunctional Soft Magnetic Composites by Cold Sintering Design

Abstract

Nacre‐mimetics hold great promise as integration of structure and function. Various techniques have been proposed to prepare nacre‐inspired materials, but in most cases, organic materials are usually used that decrease high‐temperature stability. Factually, efficient synthesis of nacre‐like high‐performance soft magnetic composites (SMCs) with good thermal stability is still challenging. Herein, a novel and simple strategy is reported on designing nacre‐like SMCs by cold sintering of ferrite‐coated alloy flakes with the absence of polymers. By selecting NH4HCO3 aqueous solution as transport solvent, a highly ordered nacre‐like structure and enhanced densification with large electrical resistivities and strong interfacial bonding are successfully achieved, which are superior to the cold‐sintered composites using water as transport solvent as well as the hot‐pressed composites based on alloy flakes and epoxy resin. The resultant composites illustrate large density (≈6.286 g cm−3) and electrical resistivity (≈3.9 × 105 Ω cm), allowing remarkable flexural strength (≈46.5 MPa), high permeability (μ′ = ≈107.3 at f = 10 MHz), together with low tanδ μ (≈0.09 at f = 10 MHz) and P cv (≈183.6 kW m−3 at 50 mT/100 kHz), which show great potential in high‐frequency power electronic and electrical systems. The synthesis strategy sheds light on designing other nacre‐like materials or developing new metal−ceramic composites.

Improved magnetic properties in amorphous FeSiBCr soft magnetic composites with easy-plane anisotropy for high-frequency applications

“…In order to meet the efficiency and conveniency requirements of future energy-conversion devices, the miniaturization and high frequency of these devices have become an inevitable trend [1,2]. Soft magnetic composites (SMCs), consisting of magnetic metal powders and an insulating layer, exhibit the advantages of high saturation magnetization, high electrical resistivity, high permeability, low core loss, and flexible shape [3][4][5][6][7][8][9]. These advantages meet all the requirements of future overlooked.…”

Tailored microwave absorption performance through interface evolution by in-situ reduced Fe nanoparticles on the surface of FeSiAl microflake

“…Electromagnetic (EM) absorbing material, which can absorb/attenuate the energy of incident EM wave in space and reduce or eliminate the reflected EM wave, is the key to improve the quality of electronic components [1][2][3][4][5]. With the advent of electrification technology, Internet of Things, and 5G era, the continuous demand for miniaturization, high efficiency and high frequency of electronic devices have led to serious EM pollution and EM interference [6,7]. Therefore, effective EM absorbing materials with merits of thin absorbing thickness, light weight, wide effective absorption bandwidth and strong absorption ability need to be exploited to adapt to increasing EM pollution and EM interference issues [8].…”