Nano-Fe3C/Fe In Situ Deposited on N-Doped Carbon Aerogel for Tunable Microwave Absorption within Ultralow Filler Loading

To suppress the ever-increasing challenge of electromagnetic radiation pollution and exploit lightweight wave absorbers, enormous attention has been focused on aerogels. Herein, a sequence of Fe3C/Fe/NC aerogels with variable dielectric/magnetic ratios has been successfully synthesized by redox reaction, freeze-drying, and high-temperature calcination. Benefiting from the dielectric-magnetic coupling loss, optimized impedance matching, and structural advantages, the Fe3C/Fe/NC-2/PVDF composite displays optimal microwave absorption performance with a minimum reflection loss (RLmin) value of −59.03 dB at 2.53 mm under an ultralow filler loading of 3 wt %. Meanwhile, the maximum effective absorption bandwidth (EAB) of Fe3C/Fe/NC-3/PVDF composite nearly covers the entire X-band at 2.92 mm. Moreover, the radar cross-section (RCS) simulation results and infrared thermal images respectivelly verify their application potential in radar wave attenuation and the infrared stealth domain. The specific wave absorption mechanism is mainly ascribed to dielectric loss, including conduction loss and polarization loss, magnetic loss containing eddy current loss and exchange resonance, as well as multiple reflections and scattering caused by the porous structure. This study can effectively decouple the impedance matching and microwave dissipating ability by dielectric/magnetic ratio modulation and microstructure design, which is of great significance for the development of lightweight and advanced wave absorbers.