Study on the microwave absorbing properties of Fe nanoparticles prepared by the HEIBE method in expanded graphite matrix composites

摘要

Recent findings reveal that expanded graphite (EG) composite with metal nanoparticles has an excellent performance in the field of absorbing materials. The N-dope broken EG/FeNPs (NBEG/Fe) composites with sandwich structure and low graphitization degree were prepared through hydrothermal reaction. The doping N element further enhances the electrical conductivity of EG, the purpose is to be consistent with the high permeability of the core-shell Fe/Fe3O4 nanoparticles (FeNPs), which can effectively improve the matching impedance. The experimental results in the 2-18 GHz range prove that NBEG/Fe has better absorption performance than pure EG and BEG/Fe, and by changing the content of FeNPs, the purpose of effectively absorbing electromagnetic microwaves in different frequency bands can be achieved. With only 10% addition of NBEG/Fe, when the matching frequency is 15.67 and 4.51 GHz, and the matching thickness is 1.42 and 5.40 mm, the reflection loss (RL) of NBEG/Fe reaches -56.75 and -43.3 dB, the RL value of NBEG/Fe has also reached an effective absorption bandwidth of 3.92 GHz (RL <= 20.0 dB) in the interval 4.06-10.64 GHz. In particular, the RL value of NBEG/Fe in the S-band (at 3.74 GHz) reaches -40.3 dB at a thickness of 6.5 mm. Moreover, under the matching frequency and matching thickness good absorption performance (RL < -20.0 dB) from 2.00 GHz to 18.00 GHz is obtained. (C) 2020 Elsevier B.V. All rights reserved.