All-Ceramic SiC Aerogel for Wide Temperature Range Electromagnetic Wave Attenuation

Abstract

A novel type of all-ceramic SiC aerogel was fabricated by freeze casting and carbothermal reduction reaction processes using graphene oxide (GO) doped SiC nanowires suspensions as starting materials. The effect of GO addition (0, 1, 2, and 4 mg/mL) on the porous morphologies, chemical composition, and the electromagnetic (EM) performance of the SiC aerogels were investigated. The optimum all-ceramic SiC aerogel exhibits effective whole X-band attenuation (>90%) at a fixed thickness of 3.3 mm from room temperature to 400 °C. It is ultralight with a density of 0.2 g/cm 3 and possesses a low thermal conductivity of about 0.05 W/mK. The material composition remains stable at temperatures up to 800 °C. The lightweight, high thermal stability, low thermal conductivity, and excellent X-band attenuation performance at a fixed thin thickness make the allceramic SiC aerogels potential EM attenuation materials for many applications in harsh environments.

Alpha Al2O3 Nanosheet-Based Biphasic Aerogels with High-Temperature Resistance up to 1600 °C

“…Figure j presents the XPS spectra of Si 2p and Al 2p for the ANSAs. The spectrum of Si 2p can be divided into two peaks corresponding, respectively, to a Si–O 2 bond at 103.1 eV and a Si–O–Al bond in the mullite phase at 102.5 eV. , Meanwhile, the spectrum of Al 2p split into two peaks, one at 74 eV corresponding to Al–O–Al in α-Al 2 O 3 and the other at 74.7 eV related to the Al–O–Si from the mullite . The FTIR spectra display the vibrational peak of Si–O–Al at 1202 cm –1 , as shown in Figure S11.…”

SiCN ceramics with controllable carbon nanomaterials for electromagnetic absorption performance

“…Schematic diagram of the analyzed electromagnetic wave absorption mechanism for the SiCN‐M ceramic nanocomposite (A), minimum reflection loss ( RL min ) and effective absorption bandwidth ( EAB ) achieved in this work compared with representative carbon material modified polymer‐derived ceramics composites (B) 13,17,19,23,25,34,39,42‐45 …”

“…Therefore, the synergistic effect of impedance matching, polarization, and conduction loss leads to an excellent EMA capability of the SiCN-M ceramic nanocomposite. Compared to other reported PDCs modified by different C materials (Figure 10B) 13,17,19,23,25,34,39,[42][43][44][45] and with different shapes (Table S2), in situ generated NG in SiCN matrix exhibits superior EMA performance with an RL min of −61.08 dB and EAB of 4.053 GHz.…”

“…Combined with the above analysis, it demonstrates that F I G U R E 1 0 Schematic diagram of the analyzed electromagnetic wave absorption mechanism for the SiCN-M ceramic nanocomposite (A), minimum reflection loss (RL min ) and effective absorption bandwidth (EAB) achieved in this work compared with representative carbon material modified polymer-derived ceramics composites (B). 13,17,19,23,25,34,39,[42][43][44][45] NG enhances the loss capacity of SiCN ceramics, especially the polarization loss, thus improving the EMA capacity.…”

Phase-Transformation Nanoparticles Synchronously Boosting Mechanical and Electromagnetic Performance of SiBCN Ceramics

“…The research on advanced electromagnetic (EM) wave absorbing materials has been a hot spot in tackling the problems associated with EM interference in harsh environments. − Aside from excellent absorption performance, , the combination of fine loading capability, high-temperature oxidation resistance, and light weight , also need to be considered for advanced EM wave absorbing materials. Silicon-based ceramics have been widely investigated because of their high temperature resistance, superior oxidation resistance, and creep resistance properties. , As a typical silicon-based ceramic, precursor-derived silicoboron carbonitride ceramic (PDC-SiBCN) demonstrates structural controllability, compositional homogeneity, low-temperature synthesis, and processing flexibility. − These prominent features make it more effective in preparing fibers, films, and coatings for various applications in extreme environments. − In particular, owing to its adjustable dielectric properties, PDC-SiBCN has an absolute advantage in EM wave absorption. − However, the main challenge in developing PDC-SiBCN as a load component is its high shrinkage, which results in the formation of defects during organic to inorganic transitions due to the release of gases .…”