With the rapid development of 5G communication technology and the Internet of Things, electromagnetic (EM) pollution and interference have become increasingly serious, endangering human health and disrupting the stable operation of electronic devices. Electromagnetic absorption materials, capable of converting EM wave energy into heat, are considered an effective solution to this problem. However, conventional microwave absorbing materials often suffer from significant variations in absorption performance with thickness. Achieving broad bandwidth, strong absorption, and stable microwave absorption performance remains a challenge.
Methods
Material preparation: Flaky FeSiAl powders were first prepared by vertical ball milling. Subsequently, polydopamine (PDA) and polyethyleneimine (PEI) layers were coated onto the surface of the flaky FeSiAl via co-deposition in an alkaline solution. Material characterization: X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to characterize the phase, morphology, and microstructure of the materials. Performance testing: A vector network analyzer was employed to measure the electromagnetic parameters and microwave absorption performance of the materials.
High efficiency and stability: The prepared FeSiAl@PDA/PEI composites exhibited broad bandwidth, strong absorption, and stable absorption performance in the 2-14 GHz range. Strong absorption capacity: The minimum reflection loss (RL) values of the FeSiAl@PDA/PEI flakes exceeded -20 dB in the thickness range of 2.5-8.9 mm. Excellent stability: When the effective absorption bandwidth (EAB) changed by 10%, the corresponding change in absorption thickness was only 28.57%. High absorption efficiency: When the absorption efficiency (RE) changed by 10%, the corresponding change in absorption thickness was only 15.63%.
This study reveals the contribution of phase cancellation and electromagnetic loss to achieving high-efficiency and stable microwave absorption performance. The macroscopic structural design further expands the absorption bandwidth and significantly enhances the absorption capacity. This work provides new insights and methods for developing high-performance electromagnetic absorption materials and addressing electromagnetic pollution.
Fig. 1. (a) Survey spectra and detailed spectra of (b) O 1s, (c) Al 2p and (d) Fe 2p for FSAPP-24 and raw powder.
Fig. 2. (a-d) 2D contour plots, (e-h) 2D Zim-f-t curves and (i-l) summarized EABₘ and |RLₘ| with the representative thickness t.
The first author of this work is Feng-Yuan Shen from Hangzhou Dianzi University. Prof. Xian-Guo Liu from Hangzhou Dianzi University is the corresponding author of this paper.
F. Shen, Y. Wan, H. Yao, X. Liu, D. Lan, Stable and efficient microwave absorption performances: Design from polydopamine/polyethyleneimine encapsulated FeSiAl flaky composites to frustum of a cone array, Journal of Alloys and Compounds 1005 (2024) 176229. https://doi.org/10.1016/j.jallcom.2024.176229
