High-attenuation and broadband microwave absorption of robust and thermally stable SiOC ceramic aerogels derived from interpenetrating silicone double network structure
Aoqing Yan, Guixiang Li, Zhe Su, Liang Li, Yi Luo, Hao Tian, Yu Cao, Yayun Zhang, Bo Niu, Donghui Long
Abstract
Polymer-derived SiOC (PD-SiOC) ceramic aerogels (CA) are widely recognized as ideal electromagnetic wave (EMW) absorbers; however, achieving high-attenuation microwave absorption and gaining an in-depth understanding of dielectric loss mechanisms remain challenging. Herein, a robust and thermally stable PD-SiOC CA was synthesized by pyrolyzing a silicone aerogel with an interpenetrating double network structure, which exhibited EMW attenuation performance. Notably, the interpenetrating double network structure containing both a carbon-rich and a silica-rich framework, facilitates the formation of numerous SiO 2 -C heterogeneous interfaces, enhancing dielectric polarization and improving impedance matching. The highly porous structure of CAs (porosity > 49 %) enhances macroscopic interfacial polarization and multiple scattering, further attenuating EMW energy. As a result, CA-1400 demonstrates exceptionally high attenuation, with a reflection loss of –73.8 dB (>99.99999 % absorption) at 8.01 GHz and a thickness of 4.28 mm, along with a wide effective absorption bandwidth of 6.72 GHz at thickness of 2.71 mm. Additionally, CAs exhibit lightweight characteristics with a density ranging from 0.66 to 1.21 g/cm 3 , excellent mechanical properties with compressive strengths ranging from 9.0 to 56.9 MPa, outstanding oxidation resistance , and superior thermal insulation with thermal conductivities ranging from 0.226 to 0.358 W·m −1 ·K −1 . This work thoroughly investigates the high-temperature structural evolution and dielectric polarization loss mechanisms of PD-SiOC CAs, offering a novel approach for the practical application of high-performance CA microwave absorbers.