Additive manufacturing of broadband electromagnetic wave absorbing materials: Polymer-derived SiC/Si3N4 composites with triply periodic minimal surface meta-structure

High temperature ceramic-based electromagnetic wave (EMW) absorbing materials has been widely studied as multifunctional materials for the application in various high-speed vehicle. However, current high temperature EMW absorbing materials are limited by narrow absorption bandwidths due to their inferior impedance matching characteristics across a wide frequency range. This study proposes a novel polymer-derived SiC (PDCs-SiC)/Si3N4 triple periodic minimal surface (TPMS) meta-structure inspired by the gyroid bionic structure. The presented design strategy integrates the material and meta-structure properties, which was inspired by the interaction mechanism between these properties on the EMW absorption performance of the prepared composites. The TPMS meta-structure were fabricated through three-dimensional (3D) printing combined with precursor infiltration pyrolysis technology, followed by annealing treatment and Al(H2PO4)3 sol infiltration. The results demonstrated that the dielectric constants of the composites were reduced through annealing treatment and Al(H2PO4)3 sol infiltration process, thereby improving impedance matching and enhancing the EMW absorption performance. The effective absorption bandwidth (EAB) of the prepared PDCs-SiC/Si3N4 composites reached 3.52 GHz at a thickness of 3.3 mm. Furthermore, TPMS meta-structure with DSM unit demonstrated the excellent absorbing properties with a wide absorption bandwidth of 11.12 GHz, as evidenced by simulations and experiments. This can be attributed that the fully connected porous TPMS meta-structure further improved the impedance matching and enhanced the transmission path of electromagnetic waves, while the discontinuous unit in the top layer of DSM induced electromagnetic wave resonance and interference cancellation, thereby enhancing the EMW absorption performance of composites. This study presents an innovative development strategy for designing and preparing high-temperature electromagnetic wave absorbing materials with broad bandwidth.