Optimized microwave absorption properties for TiB2@BN/PDMS composites by constructing TiB2@BN heterogeneous interface

The single electromagnetic (EM) wave loss mechanism leads to suboptimal microwave absorption in dielectric loss materials. However, introducing different materials and constructing distinctive microstructures can significantly improve microwave absorption. Herein, Titanium diboride (TiB2) and TiB2@BN powders were synthesized via the boron thermal reduction and chemical solution methods. The microwave absorption and thermal properties of TiB2/polydimethylsiloxane (PDMS) and TiB2@BN/PDMS composites were investigated. Compared to TiB2/PDMS, TiB2@BN/PDMS composites achieve enhanced microwave absorption across the 2–18 GHz. The minimum reflection loss (RLmin) reaches -31.2 dB at 17.92 GHz with 60 wt% TiB2@BN and a thickness of 1.55 mm. RL below -10 dB covers the frequency range of 12.88–18 GHz with 65 wt% TiB2@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 TiB2@BN heterointerface can optimize impedance matching and electromagnetic wave attenuation, thereby enhancing microwave absorption. Charge transfer from B and N atoms to Ti atoms, combined with lattice defects, generates strong interface and dipole polarization loss under an external EM field. Additionally, TiB2@BN/PDMS composites possess excellent thermal conductivity. These results highlight the potential of TiB2@BN/PDMS composites in advanced microwave absorption and thermal management applications单一电磁波（Electromagnetic Wave，简称EM）损耗机制会使介电损耗材料的微波吸收性能未达最优。然而，引入多元材料并构建独特微观结构，可显著提升微波吸收性能。本文通过硼热还原法与化学溶液法，合成了二硼化钛（Titanium diboride，TiB2）与TiB2@BN粉体。随后研究了TiB2/聚二甲基硅氧烷（Polydimethylsiloxane，PDMS）与TiB2@BN/PDMS复合材料的微波吸收性能与热学性能。与TiB2/PDMS复合材料相比，TiB2@BN/PDMS复合材料在2–18 GHz全频段内的微波吸收性能均得到提升。当TiB2@BN填充量为60 wt%、样品厚度为1.55 mm时，其最小反射损耗（Minimum Reflection Loss，RLmin）在17.92 GHz处可达-31.2 dB。当TiB2@BN填充量为65 wt%、样品厚度为1.75 mm时，反射损耗低于-10 dB的有效吸收频段覆盖12.88–18 GHz。雷达散射截面（Radar Cross-section，RCS）仿真结果表明该材料具备优异的隐身性能，可适配实际应用场景。构建TiB2@BN异质界面可优化阻抗匹配与电磁波衰减能力，进而提升微波吸收性能。在外加EM场作用下，B、N原子向Ti原子的电荷转移结合晶格缺陷，可产生强烈的界面极化与偶极极化损耗。此外，TiB2@BN/PDMS复合材料还具备优异的导热性能。上述研究结果凸显了TiB2@BN/PDMS复合材料在先进微波吸收与热管理应用领域的应用潜力。