Polymer Derived SiOC/β-SiC Nanocomposites with Spatially Confined Carbon Nanotubes for Electromagnetic Wave Attenuation

High Resolution Image Download MS PowerPoint Slide Lightweight polymer-derived ceramics offer exceptional thermal and chemical stability but exhibit limited performance in electromagnetic wave (EMW) absorption due to low dielectric loss. This study presents a layered β-SiC/SiOC nanocomposite architecture fabricated via direct ink writing (DIW), with carbon nanotubes (CNTs) spatially confined to the central layer. β-SiC functioned as a rheology modifier, making the inks DIW-printable, while simultaneously enhancing dielectric loss. CNTs contributed to improved conductivity and interfacial polarization losses. The three-layer design, with porous β-SiC/SiOC top and bottom layers, allows EMW penetration and reduces surface reflections, while the CNTs in the middle layer promote internal reflections and prolong EMW interaction within the absorber. Transmission electron microscopy revealed core–shell-like CNT-SiOC interfaces, highlighting the role of interfacial polarization in energy dissipation. Among the sample compositions tested (samples with 0, 1, and 2 wt % CNT content), the intermediate CNT content (CNT-1) exhibited the highest performance, achieving a minimal reflection loss of −59.47 dB at a thickness of 3.39 mm, maximum effective absorption bandwidth covering ∼88% of the X-band, and high absorption efficiency per unit thickness (EAB max /d ∼1.16 GHz/mm). The CNT-1 also demonstrated superior compressive strength (∼1.46 MPa), nearly double that of the CNT-free composite. However, excessive CNT loading (CNT-2) led to agglomeration and reduced performance. These findings demonstrate that controlled filler distribution and architectural design enable lightweight, thin, and broadband EMW absorbers, providing a versatile strategy for next-generation functional ceramics.