A novel active-passive protection strategy endows carbonyl iron with excellent intelligent anti-corrosion and microwave absorption dual functional characteristics

Carbonyl iron absorbers (CI) face significant challenges in practical applications, such as corrosion, interface bonding failure, detachment, and high maintenance costs. Herein, we have developed intelligent self-healing technology based on proactive/passive mechanisms via <i>in situ</i> synthesis of self-healing factors (polydopamine/benzotriazole (PDA/BTA)) and physical barrier layers (SiO₂/1,1,1,3,3,3-hexamethyl disilazane, SiO₂/HMDS) to enhance corrosion resistance, while also being compatible with efficient microwave absorption characteristics. The unique multiscale structure gives full play to the utilization of the roles of each functional layer, including the intelligent self-healing features of PDA/BTA, physical shielding and spatial confinement characteristics of SiO₂/HMDS, and magnetic-dielectric synergistic mechanism resulted from the good impedance matching characteristics, the conduction loss, the interfacial polarization loss and natural resonance. The as-fabricated composites achieved an exceptional minimum reflection loss value of −55.4 dB at 10.7 GHz and the effective absorption band of 7.6 GHz. Moreover, it still exhibits obvious self-healing and corrosion resistance characteristics after 360 h corrosion treatment, ascribed to the self-healing mechanism of PDA/BTA and the blocking intervention effect of SiO₂/HMDS. This work is considered to pave the way for the synthesis of high-performance magnetic absorbers, especially in enhancing their intelligent self-healing ability in corrosive environments.