Hierarchical ZrB2@SiCnw nanocomposite aerogel via 0D/1D/3D dimensionality expansion strategy: Towards full X-band microwave absorption at high temperature

Abstract

The enhancement of electromagnetic wave (EMW) absorption at elevated temperatures constitutes a pivotal research frontier in EMW absorbing materials (EMAMs). SiC nanowire (SiC_nw) with superior thermal stability could be acted as ideal candidate to meet the challenge. However, the relatively weak and singular dielectric loss mechanism significantly limits its further applications. Herein, a 0D/1D/3D dimensionality expansion strategy was proposed to boost the EM attenuation performance. The highly conductive and oxidation resistant 0D ZrB₂ nanoparticles were decorated onto the 1D SiC nanowire to promote high temperature EM absorption capacity, followed by the synthesis of porous 3D ZrB₂@SiC_nw nanocomposite aerogel via freeze casting. The multiscale nano-architectonic aerogel possesses multiple EM attenuation mechanisms including interface polarization, conductive loss and multiple reflection. As a result, the aerogel achieves full X-band absorption from 298 K to 873 K, with the minimal reflection loss (RL_min) improved from −22.4 dB (5.8 mm) at 298 K to −61.9 dB at 873 K (3.6 mm). Moreover, the thickness tolerance (Δd) of full X-band absorption is also as wide as 0.7 mm (3.9–4.6 mm) at 873 K, which benefits the dimensional adaptability across varying service temperatures. Furthermore, the synergistic combination of ultralow density (0.107 g/cm³), thermal insulation (κ = 0.1687 W m⁻¹ K⁻¹) and oxidation resistance establish ZrB₂@SiC_nw nanocomposite aerogel as a practical EMAM served in high temperature and harsh environment.