Structural Electromagnetic Absorber Based on MoS₂/PyC‐Al₂O₃ Ceramic Metamaterials

Abstract Limited by the types of suitable absorbents as well as the challenges in engineering the nanostructures (e.g., defects, dipoles, and hetero‐interface) using state‐of‐the‐art additive manufacturing (AM) techniques, the electromagnetic (EM) wave absorption performance of the current ceramic‐based materials is still not satisfying. Moreover, because of the high residual porosity and the possible formation of cracks during sintering or pyrolysis, AM‐formed ceramic components may in many cases exhibit low mechanical strength. In this work, semiconductive MoS 2 and conductive PyC modified Al 2 O 3 (MoS 2 /PyC‐Al 2 O 3 ) ceramic‐based structural EM metamaterials are developed by innovatively harnessing AM, precursor infiltration and pyrolysis (PIP), and hydrothermal methods. Three different meta‐structures are successfully created, and the ceramic‐based nanocomposite benefit from its optimization of EM parameters. Ultra‐broad effective absorption bandwidth (EAB) of 35 GHz is achieved by establishment of multi‐loss mechanism via nanostructure engineering and fabrication of meta‐structures via AM. Due to the strengthening by the PyC phase, the bending strength of the resulting ceramics can reach ≈327 MPa, which is the highest value measured on 3D‐printed ceramics of this type that has been reported so far. For the first time, the positive effect deriving from the engineering of the microscopic nano/microstructure and of the macroscopic meta‐structure of the absorber on the permittivity and EM absorption performance is proposed. Integration of outstanding mechanical strength and ultra‐broad EAB is innovatively realized through a multi‐scale design route. This work provides new insights for the design of advanced ceramic‐based metamaterials with outstanding performance under extreme environment.