Abstract
With the rapid growth in the use of wireless electronic devices, society urgently needs electromagnetic wave (EMW) absorbing material with light weight, thin thickness, wide effective absorbing band width, and strong absorption capacity. Herein, the multi-layer magnetic composite boards are fabricated by hot-pressing magnetic fiber boards and normal veneer layer-by-layer. The magnetic fibers obtained using in-situ chemical co-precipitation are used to fabricate magnetic fiber board by hot-pressing. The magnetic wave absorbing capacities of the magnetic fiber boards obtained with 72 h impregnation time exhibit strongest adsorption capacities of −51.01 dB with a thickness of 3.00 mm. It is proved that this outstanding EMW absorption property is due to the strongest dielectric loss, the optimal magnetic loss, and the dipole relaxation polarization. Meanwhile, the EMW absorbing capacities of the corresponding multi-layer composite magnetic board increases from −14.14 dB (3-layer) to −60.16 dB (7-layer). This is due to the generated multi-interfaces between magnetic fiber board and natural wood veneer in the EMW propagation direction, which significantly benefit multireflection and attenuation of the incident waves. The results obtained in this work indicate that natural wood fibers are of great potential in the fabrication of magnetic multi-layer boards treated as EMW absorbers via a low cost, green, and scalable method.
Highlights
With the rapid growth in the use of wireless electronic devices such as mobile phones, local area networks, and household robots, people’s daily life and production are increasingly affected by electromagnetic waves generated by electromagnetic systems
We developed a facile in situ chemical co-precipitation method coupled with hotpressing processes to fabricate magnetic composite multi-layer board as electromagnetic wave (EMW) absorbing materials
The EMW absorbing properties of the as-prepared magnetic fiber boards could be adjusted via the iron salt impregnation time and the thickness
Summary
With the rapid growth in the use of wireless electronic devices such as mobile phones, local area networks, and household robots, people’s daily life and production are increasingly affected by electromagnetic waves generated by electromagnetic systems. Many research groups have fabricated a series of metal-biomass composite boards with good EMW absorption properties by chemical plating [15], or using a laminated method [16]. Poor adjustability of the electromagnetic wave absorption properties (e.g., maximum absorption value and the corresponding matching frequency) according to different application requirements To solve these problems, the Oka group firstly proposed magnetic wood, which is basically the combination of wood with a magnetic fluid or powder [14,17,18]. The fabrication of magnetic fiber board via in situ chemical co-precipitation and laminated hot-pressing, along with the investigation of the corresponding EMW absorbing properties, is rarely studied. All the results confirmed that the obtained magnetic fiber board in our work has an excellent and tunable absorbing property, which was due to the optimal impedance matching, strongest dielectric loss, optimal magnetic loss, interface polarization between biomass-Fe3O4, and interconnected conductive network for electron hopping and migrating
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