Study on the construction and microwave absorption performance of Fe_{<italic>x</italic>}O_{<italic>y</italic>}/TiO₂/C composites based on red mud

To achieve the efficient utilization and development of red mud as a resource, this study used red mud as the raw material and starch as the carbon source. By employing sol-gel technology and carbon thermal reduction processes, FexOy/TiO2/C composite microwave absorption materials were successfully prepared. By adjusting the calcination temperature and raw material ratios, the minimum reflection loss value (RLmin) and effective absorption bandwidth (EAB) of the FexOy/TiO2/C composite material. Experimental results indicate that RmCT-5.4-700 exhibits the best microwave absorption performance, with RLmin reaching −30.2 dB and EAB reaching 5.3 GHz when the coating thickness is 2.0 mm. The excellent absorption performance of the FexOy/TiO2/C composite material stems from the synergistic effects of multiple loss mechanisms. Defects generated by carbon consumption during the carbon thermal reduction process provide dipole sites, thereby inducing dipole polarization phenomena, effectively dissipating electromagnetic wave energy and enhancing absorption performance. Graphitized carbon, Fe3O4, and Fe particles collectively form a conductive network, with electrons migrating and hopping within the network, thereby generating conductive loss. Additionally, Fe3O4, Fe and TiO2 particles are uniformly distributed on the red mud matrix, forming numerous heterogeneous interfaces, thereby inducing interface polarization. The magnetic loss characteristics of Fe3O4 and Fe particles effectively improve the impedance matching properties, enabling more electromagnetic energy to enter the composite material and be efficiently absorbed. The research approach in this work not only opens up new avenues for the resource utilization of red mud but also promotes the high-value utilization of solid waste.