摘要
Compared with spherical ferromagnetic particles, flaky particles due to the higher permeability present great potentials as high-efficiency electromagnetic absorbing materials, especially in S band (2-4 GHz). FeSi flakes with different diameters were synthesized by ball-milling and subsequent screened processes, and hydrogen annealing and SiO2 coating were then utilized to further optimize the electromagnetic parameters for high-efficiency absorption. FeSi flakes with high diameter possess higher permittivity for the larger specific areas and higher permeability for the increased shape anisotropy. The decreased defects after annealing induce the reducing permittivity. The eddy current effect can be effectively suppressed after the SiO2 is coated on the surface of FeSi flakes. As for the coating containing 70 wt% FeSi@SiO2 flakes, the maximum reflection loss (RLmax) of -73 dB can be observed at 2.5 GHz with the coating thickness of 3 mm. Effective absorption band (ERL5, RL < -5 dB) can reach 13 GHz at a very thin thickness of 1 mm, and ERL5 covers the whole S-C band when the thickness of 2.5 mm is utilized. The coatings containing FeSi and FeSi@SiO2 flakes as fillers present adjustable electromagnetic absorbing (EMA) performances and can be promising candidates for EMA application, especially in S band.
-
单位aerosp res inst special mat & proc technol; harbin inst technol