Optimized microwave absorption and thermal properties for TiB@BN/PDMS composites via TiB@BN heterogeneous interface engineering.

The single electromagnetic (EM) wave loss mechanism leads to suboptimal microwave absorption in dielectric materials, whereas, introducing different materials and constructing distinctive microstructures can significantly improve microwave absorption. In this study, TiB and TiB@BN powders were synthesized using boron thermal reduction and chemical solution methods. Their microwave absorption and thermal properties were systematically analyzed. Compared to TiB/PDMS, TiB@BN/PDMS composites achieve enhanced microwave absorption across the 2-18 GHz. The minimum reflection loss (RL) reaches -31.2 dB at 17.92 GHz with 60 wt% TiB@BN and a thickness of 1.55 mm. RL below -10 dB covers the frequency range of 12.88-18 GHz with 65 wt% TiB@BN and a thickness of 1.75 mm. Radar cross-section (RCS) simulations show notable stealth capabilities, making it suitable for practical applications. Establishing the TiB@BN heterointerface can optimize impedance matching and EM wave attenuation, thereby enhancing microwave absorption. Charge transfer from B and N atoms to Ti atoms at the heterointerface, combined with lattice defects, generates strong interface and dipole polarization loss under an external EM field. Additionally, TiB@BN/PDMS composites possess excellent thermal conductivity. These results highlight the potential of TiB@BN/PDMS composites in advanced microwave absorption and thermal management applications.