Robust carbon bridge to construct double-shell FeCo@C@Al2O3 heterogeneous structure with dual-function for extraordinary microwave absorption and anti-corrosion

The complexity of the environment leads to corrosion and failure of absorbing functions. The encapsulation and surface modification of multi-gradient structures are typical ways to address this challenge. Herein, a FeCo@C@Al2O3 core–shell heterostructure is developed for the dual functions of absorbing and anti-corrosion using the chemical vapor deposition and hydrolysis of the aluminum sulfate. This unique double-shell structure provides more multiple interface relaxation polarizations, electromagnetic wave scatterings. And the robust carbon layer produces sufficient conduction loss for the FeCo@C@Al2O3. Compared with pure FeCo, the absorption capacity of FeCo@C@Al2O3 increases up to 1.4 times, the minimum reflection loss value achieves −46.7 dB at the thickness of 1.4 mm. And the maximum effective absorption bandwidth is up to 9.3 GHz. While it possesses minimum total RCS value of −13.29 dB∙m2, reflecting the optimal absorbing stealth performance. Besides, the coating Al2O3 layer effectively isolates the diffusion of corrosion ions including Cl-, H2O and O2, the corrosion current and polarization resistance of FeCo@C@Al2O3 are well adjusted to 7.96 × 10-8 A/cm2 and 5.40 × 105 Ω·cm2, respectively. Therefore, the FeCo@C@Al2O3 heterostructure provides an updated platform for the research and development of new absorbing and anti-corrosion materials.