Microstructure, Electromagnetic Properties, and Microwave Absorption Mechanism of SiO2-MnO-Al2O3 Based Manganese Ore Powder for Electromagnetic Protection

Abstract

Considering the electromagnetic protection needs of important ground buildings, exploring the electromagnetic wave (EMW) absorption performance of manganese ore powder (MOP) building materials is an effective way to overcome its low added value and difficulty in popularizing. Here, choosing filling ratios commonly used in building materials such as autoclaved bricks, MOP/paraffin samples with 20%, 40%, and 60% mass fraction of MOP were prepared, and electromagnetic properties were analyzed at 2–18 GHz using the coaxial method. The results show that 60 wt% sample has the best absorption performance, with a minimum reflection loss (RLmin) value of −22.06 dB at 15.04 GHz, and the effective absorption bandwidth (EAB, RL < −10 dB) reaches 4.16 GHz at a 7.65 mm absorber thickness, covering most of the Ku-band region. The excellent microwave absorption performance of MOP is due to its multi-oxide forming multi-interface structure and rough surface, which can not only form abundant dipole and interfacial polarization under the action of EMW, but also reflect and scatter the incident EMW, prolong the transmission path, and enhanced the absorption of microwaves. This study demonstrates that MOP building materials can have excellent microwave absorption properties, thus becoming a new way to address harmful manganese residue; for example, autoclaved bricks, which can not only improve the added value of manganese residue building materials but also can be consumed on a large scale. It provides a new idea to solve the harm of manganese residue.

The In Situ Preparation of Ni–Zn Ferrite Intercalated Expanded Graphite via Thermal Treatment for Improved Radar Attenuation Property

“… represents the degree of polarization of the materials in the electric field, including interfacial polarization and dipole polarization. The values in Figure 9 a decrease with increasing frequency; due to the acceleration of the electric field period with increasing frequency, the dipoles in the materials cannot be quickly reoriented [ 43 ]. The values of NZF/EG are greater than that of EG which is due to the enhanced interfacial polarization caused by the introduction of NZF.…”

“…ε ′ represents the degree of polarization of the materials in the electric field, including interfacial polarization and dipole polarization. The ε ′ values in Figure 9a decrease with increasing frequency; due to the acceleration of the electric field period with increasing frequency, the dipoles in the materials cannot be quickly reoriented [43]. The ε ′ values of NZF/EG are greater In order to better understand the electromagnetic loss mechanism of as-prepared composites, the real and imaginary parts of the complex permittivity and complex permeability of EG, NZF/EG-0.5, and NZF/EG-1.0 are analyzed in detail.…”

Well-matched PANI@FePO4@FeSi hybrid composite with excellent microwave absorption property

“…Fe, Co or Ni magnetic metal-based composites play critical role as microwave absorbing materials for their large permeability, high saturation magnetization and curie temperature [1][2][3][4]. However, the skin effect weakens impedance matching and restrains further improving microwave absorption ability [5][6][7][8]. To address these issues, coating of non-magnetic dielectric material can effectively isolate the metal particles, suppress the eddy current effect.…”