Hierarchically engineered CI@KH570@PC composites with dual-functionality for exceptional corrosion resistance and microwave absorption

Corrosion-induced aging degrades the microwave absorption properties of magnetic functional materials, thereby constraining their applicability in practical application environments. Herein, a magnetic composite absorber (CI@KH570@PC) with outstanding anti-corrosion ability was synthesized by modifying carbonyl iron (CI) with methacryloxypropyl trimethoxysilane (KH570) and parylene C (PC) through chemical vapor deposition polymerization. Electrochemical test results demonstrate that the CI@KH570@PC composite exhibits exceptional resistance to corrosion compared with CI. The corrosion potential shifts from −0.87 V to −0.29 V vs. Ag/AgCl, and the corrosion current density is reduced to 2.141 μA/cm², resulting in a protective efficiency of 97.4 %. This significant enhancement is due to the effective spatial shielding and high impedance characteristics provided by the PC layer. In addition, molecular dynamics simulations were utilized to explore the corrosive agents' diffusion behavior, thereby elucidating the barrier protection mechanism against corrosion. Electromagnetic performance tests indicate that CI@KH570@PC composite achieves a minimum reflection loss of −62.36 dB at 5.4 GHz, while its effective absorption bandwidth extends to 7.35 GHz at 1.38 mm, delivering a powerful, broad, and thin absorption effect. This enhanced performance arises from the introduction of a gradient structure, which diversifies multiple electromagnetic loss mechanisms involving dipole and interfacial polarization. RCS simulations confirm composite's excellent microwave absorption capabilities under real radar wave conditions.