In-situ growth of SiC nanowires@carbon nanotubes on 3D printed metamaterial structures to enhance electromagnetic wave absorption

Impedance matching and attenuation principles are decisive for electromagnetic wave (EMW) absorption materials to achieve wider absorption bandwidth and higher strength absorption. By designing macrostructures to obtain metamaterials and tuning microstructures of absorption materials, impedance matching characteristic and absorption performance can be readily improved. In this paper, three-dimensional (3D) printing technology as well as precursor infiltration and pyrolysis (PIP) method were utilized to fabricate Al₂O₃/carbon nanotubes/SiC nanowires/SiOC composites with twisted cross metamaterial structures, where carbon nanotubes (CNTs) acted as a nucleating agent to obtain SiC nanowires (SiCnw) and as conductive phase to form conductive net structure, thus improving the dielectric and conductive loss of the composites. The Al₂O₃/CNT/SiCnw/SiOC composites achieved a minimum reflection coefficient (RC_min) value of −56.84 dB (99.999%) at 12.2 GHz with a thickness of 2.8 mm and the effective absorption bandwidth (EAB) ranges from 8.2–12.4 GHz with a thickness of 3.2 mm, covering the whole X-band. The excellent EMW absorption performance of the composite with metamaterial structure makes it possible to be practically applied.