Tunable Broadband TiO₂@TiC Composites by In Situ Surface Oxidation for Electromagnetic Wave Absorption

Titanium carbide (TiC) exhibits excellent chemical stability and high electrical conductivity, making it suitable for composites with unique structures and exceptional absorption abilities. In this work, TiO₂@TiC composites with varied morphology were synthesized by oxidizing TiC at 400°C, for various durations. With the increase of oxidation time, small white TiO₂ particles grew in situ on the surface of TiC particles, ultimately leading to the formation of a continuous structure in which TiO₂ covered the surface of the TiC particles. These results indicate that the impedance matching and electromagnetic wave (EMW) absorption properties of TiO₂@TiC composites can be modified by adjusting the oxidation time. The minimum reflection loss (RL_min) of the highly oxidized TiO₂@TiC composite (TO-4 sample) reached −16.2 dB at a thickness of 2.9 mm. When the thickness was increased from 1.2 mm to 4.7 mm, the composites achieved the broadest effective absorption bandwidth of 13 GHz (from 5 to 18 GHz). These enhanced EMW absorption properties can be ascribed to the presence of defects, pores, heterointerfaces, TiO₂, and TiC within the composites, which induce dipole polarization loss, interface polarization loss, and conduction loss. This practical solution provides a method for preparing TiO₂@TiC materials with EMW-absorbing properties using oxidation technology.