Design and preparation of an epoxy resin matrix composite structure with broadband wave-absorbing properties

Aiming at the poor effect of broadband wave -absorbing, the structural wave -absorbing composites structure were designed and prepared by choosing FeNi alloy powder/epoxy nanocomposites as the wave -absorbing interlayer, and carbon fibers/epoxy composites as the structural materials. Firstly, "80 wt% Fe50Ni50 alloy powder/epoxy resin nanocomposites" were successfully prepared, with a density of about 2.4 g/cm3, which can be applied as wave -absorbing interlayer. Then, electromagnetic parameters and loss mechanisms of the wave -absorbing sandwich in the frequency band of 1-18 GHz were studied in detail. Finally, the radar wave absorption characteristics of the structural wave -absorbing composites were optimized. The study shows that the electromagnetic loss mechanism of wave -absorbing sandwich is dominated by conductive loss and eddy current loss in the frequency range of 1-6 GHz, and eddy current loss, resonant loss and relaxation polarization in the frequency range of 6-18 GHz. In the frequency band of 2.5-8 GHz, the angular tangent of the magnetic loss of the interlayer is tan delta m >= 0.5, and, the attenuation constant is stabilized in the range of 160-180 in the frequency band of 5.2-13.2 GHz, which shows that the interlayer has a good capacity of electromagnetic wave absorption. Different wave -absorbing properties can be designed by changing the thickness of the wave -absorbing interlayer. And the "fiberglass/interlayer/carbon fiber" composite board with a thickness of 2.0 mm interlayer and 3.0 mm -thick "fiberglass/ epoxy" has excellent broadband wave -absorbing properties. The sandwich composites have waveabsorbing peaks of 'RL'>= 10 dB in the frequency bands of 4.93-8.79 GHz and 14.96-18.0 GHz, with the peak width of 6.90 GHz, and the absorption peak of 'RL'>= 54 dB.