• • The optimal composite RmCT-5.4-700 achieves RLmin of -30.2 dB at 14.0 GHz and EAB of 5.3 GHz at 2.0 mm thickness, demonstrating superior microwave absorption suitable for thin coating applications.
• • The synthesis employs red mud as raw material and starch as carbon source via sol-gel and carbothermal reduction, enabling cost-effective and scalable production from industrial waste.
• • The composite leverages multiple loss mechanisms: dipole polarization from defects, conductive loss from graphitized carbon network, interfacial polarization from heterogeneous interfaces, and magnetic loss from Fe3O4/Fe, leading to enhanced attenuation and impedance matching.
• • The material achieves high absorption performance with a low filler loading (implied by coating thickness), indicating potential for lightweight and high-efficiency electromagnetic wave absorbers.