3D-printed oblique honeycomb Al₂O₃/SiCw structure for electromagnetic wave absorption

For electromagnetic wave (EMW) absorption materials, combining microstructure design with macrostructure design is considered as an effective means to adjust EMW absorption performance. Undoubtedly, the great advantages of three-dimensional (3D) printing technology in structural design and accurate molding provide a convenient and feasible research scheme for the adjustment of EMW absorption performance. In this study, a method combined 3D printing technology with direct chemical vapor infiltration (CVI) has been adopted to fabricate Al₂O₃/SiC whisker (SiCw) honeycomb composites. The porous oblique honeycomb structures with well-designed angle (30°, 45°, 60° and 75°) and micron-scale SiCw effectively improved impedance match, inner scattering and dielectric loss, which resulted in the realization of the optimized wave absorbing composites. Specially, Al₂O₃/SiCw composite with the angle of 30° shows a minimum reflection coefficient (RC_min) value of −63.65 dB (99.9999%) absorption at 9.8 GHz with a thickness of 3.5 mm while the effective absorption bandwidth (EAB) ranges from 8.2 to 12.4 GHz, covering the whole X band. Besides, the EMW absorption mechanism for 3D printed Al₂O₃/SiCw composite is also discussed. As a proof of concept, this strategy provides a novel and effective avenue to fabricate structural composites with broader and higher microwave absorption performance.