Reduced Graphene Oxide/Silicon Nitride Composite for Cooperative Electromagnetic Absorption in Wide Temperature Spectrum with Excellent Thermal Stability

Abstract

The fabrication of a sandwich-like composite that consists of reduced graphene oxide (RGO) and Si 3 N 4 ceramic (RGO/Si 3 N 4 ) was achieved through the combination of modified freeze-drying approach and chemical vapor infiltration process. Due to a hierarchical structure and a high ratio of I D /I G (1.27), the RGO/Si 3 N 4 exhibits an unprecedented high polarization relaxation loss (PRL), which accounts for 32% of the whole dielectric loss. The outstanding PRL endows the RGO/Si 3 N 4 composites with unique temperature-independent dielectric properties and electromagnetic (EM) wave absorption performance. Even at a low absorbent content of only 0.16 wt %, the effective absorption bandwidth of RGO/Si 3 N 4 composites can cover the whole Xband (8.2−12.4 GHz) at broad sample thicknesses ranging from 4.3 to 4.6 mm and temperatures ranging from 323 to 873 K. The mechanism for the enhancement of PRL and conductive loss was explicitly investigated. The outstanding absorption performance toward EM waves indicated that the resultant porous RGO/Si 3 N 4 composite can be a promising candidate for the applications under elevated temperature.

Enhanced Magnetic Microwave Absorption at Low‐Frequency Band by Ferrite Assembled Microspheres with Controlled Components and Morphologies

“…Moreover, by virtue of this hierarchical assembly, some reflection sites have been fabricated, encouraging the absorption toward incident electromagnetic waves because of the opposite phases. [ 22 ] All in all, their better | Z in / Z 0 | values and improved electromagnetic dissipation capacity can be realized under a thin thickness, well explaining the boosted MA performance.…”

Polymer-derived SiOC reinforced with core-shell nanophase structure of ZrB2/ZrO2 for excellent and stable high-temperature microwave absorption (up to 900°C)

“…Microwave effective absorption bandwidth (EAB) of ceramic composite in this work and ceramic-based composites reported in literature. [8,9,13,[27][28][29][30][31][32][33][34][35][36][37] where l, R, S are the thickness, resistance, and sectional area of the samples. The reported conductivity was the average value from three samples of each type.…”

1D CNT-Expanded 3D Carbon Foam/Si3N4 Sandwich Heterostructure: Utilizing the Polarization Compensation Effect for Keeping Stable Electromagnetic Absorption Performance at Elevated Temperature

“…10 Cao et al introduced SiO 2 as a protecting matrix to prevent inner 2D carbon nanotubes (MWCNTs) from oxidation and achieve EM absorbing ability up to 500 °C. 11 Our group fabricated rGO/Si 3 N 4 heterostructures that can be applied at 600 °C, 12 benefiting from the maintained 3D porous foam/aerogel structure and the improved thermal stability. However, such a mainstream idea of merely combining two different phases will lead to deteriorating performance with the rising to −15 dB 12 during the temperature-elevating process, respectively.…”