Preparation and microwave absorption properties of Fe3O4/activated carbon composites for naval ship stealth

To address the urgent need for lightweight, wideband (S-C band) microwave absorbing materials for naval ship stealth, this study designed and prepared Fe 3 O 4 /activated carbon (Fe 3 O 4 /AC) composites using a solvothermal method. By controlling the distribution of Fe 3 O 4 nanoparticles within the hierarchical pores of AC, a magneto-dielectric synergistic loss system was constructed. At a Fe 3 O 4 :AC mass ratio of 20:5 (Sample S5), the material demonstrated breakthrough wave absorption performance at a practical thickness of 5.0 mm: a minimum reflection loss (RL) of − 42.63 dB at 6.0 GHz and an effective absorption bandwidth (EAB, RL ≤ − 10 dB) of 3.12 GHz (4.16–7.28 GHz), fully covering the critical S–C band (2–8 GHz) for shipborne radar. This performance enhancement arises from the synergistic effect between enhanced interfacial polarization relaxation due to AC’s hierarchical pore structure and the magnetic loss (dominated by low-frequency natural resonance) from Fe 3 O 4 . This synergy significantly optimizes impedance matching and excites λ/4 interference cancellation. This study provides a lightweight composite with strong absorption and broad bandwidth in the S–C band, offering potential for naval stealth applications.