Polyurea-Integrated Fe₃SnC/Sn/CNF Hybrid for Enhanced Broadband Microwave Absorption

Effective mitigation of electromagnetic microwave (EMW) pollution requires the development of lightweight, broadband, and high-performance microwave absorbing materials. In this work, a novel Fe₃SnC/Sn/CNF composite is synthesized via a combination of hydrothermal synthesis, electrospinning, and high-temperature carbonization. The optimal sample (FSC3) achieved a minimum reflection loss (RL_min) of −28.33 dB and an effective absorption bandwidth (EAB) of 6.40 GHz at a thickness of 2.50 mm. To enhance environmental durability and broaden application potential, FSC3 is incorporated into a polyurea (PUA) matrix to fabricate a composite coating. The resulting material exhibited significantly improved microwave absorption, with an RL_min of −65.78 dB and an EAB of 6.68 GHz at only 2.17 mm thickness. This enhancement is attributed to increased interfacial and dipolar polarization, as well as improved impedance matching due to the synergy between the filler and the elastomer matrix. Computer Simulation Technology (CST) simulations confirmed excellent Radar Cross Section (RCS) reduction performance, validating its stealth potential. Furthermore, the composite coating displayed enhanced mechanical strength and a hydrophilic surface, broadening its application prospects in harsh environments. This work presents a scalable and versatile strategy for designing multifunctional microwave absorbing coatings with outstanding performance.