Enhanced Flexibility and Microwave Absorption Properties of HfC/SiC Nanofiber Mats

Abstract

Hafnium carbide (HfC) phase, with a high melting point, excellent strength, and high electrical conductivity, could be a suitable addition to enhance the microwave absorption properties of one-dimensional silicon carbide (SiC) nanomaterials without sacrificing its high-temperature thermal stability. In the present work, HfC/SiC hybrid nanofiber mats with different HfC loading contents are fabricated by electrospinning and high-temperature pyrolysis. HfC hybrids with sizes of 5-10 nm are embedded in the SiC nanofibers. As the HfC content increases from 0 to 6.3 wt %, the average diameter of the fibers drops from 2.62 μm to 260 nm. Meanwhile, the electrical conductivity rises from 7.9 × 10 to 4.2 × 10 S/cm. Moreover, the flexibility of the nanofiber mats is also greatly improved, according to a 200-times 180° bending test. Furthermore, compared with pure SiC fiber mats, the HfC/SiC nanofiber mats possess much larger dielectric loss because of higher electrical conductivity. At the optimal HfC content of 2.5 wt %, the HfC/SiC nanofibers/silicon resin composite (10 wt %) exhibits a minimal reflection loss (RL) of -33.9 dB at 12.8 GHz and a 3 mm thickness with a broad effective absorption bandwidth (RL < -10 dB) of 7.4 GHz. The above results prove that introducing HfC into SiC nanofiber mats is an effective way to enhance their flexibility, dielectric properties, and microwave absorption performance.

Oriented Polarization Tuning Broadband Absorption from Flexible Hierarchical ZnO Arrays Vertically Supported on Carbon Cloth

“…To fabricate large‐scale, lightweight, and broadband MA materials, conductive carbon composites with special structure have been extensively studied, such as MWCNTs, carbon fiber, cotton cloth, and carbon cloth (CC) . Ji and co‐workers synthesized cotton/zeolitic imidazolate framework (ZIF) and carbon‐cotton/Co@nanoporous carbon absorber from biomass cotton .…”

Tuning the Dielectric and Microwaves Absorption Properties of N-Doped Carbon Nanotubes by Boron Insertion

“…In Figure 3a S4 (Supplementary Materials); with decreased B content, the B atomic percent showed an upward trend, the N atomic percent first decreased and then increased, the C atomic percent showed a trend of increasing and then decreasing; consistent with the variation of B-C and B-N groups in the B,N-CNTs. The reflection loss (RL) of carbon nanomaterial can be used to characterize its MA property in the transmission-line theory, and the calculation formulas are shown in Equations (1) and (2) [38]:…”

“…The improvement of MA performance of B,N-CNT-2 was mainly caused that the appropriate addition of B element led to more defects on the surface of B,N-CNT and thus increased the interfacial polarization of the absorbent. Compared with the RL curve of B,N-CNT-2, it was clearly shown that the lowest RL of B,N-CNT-3 was increased to −16.5 dB at 18 GHz, and the effective absorption bandwidth was only 1 GHz with a thickness of 5 mm The reflection loss (RL) of carbon nanomaterial can be used to characterize its MA property in the transmission-line theory, and the calculation formulas are shown in Equations ( 1) and (2) [38]:…”

“…The reflection loss ( RL ) of carbon nanomaterial can be used to characterize its MA property in the transmission-line theory, and the calculation formulas are shown in Equations (1) and (2) [ 38 ]: where Z in represents the input impedance of MA materials, Z 0 stands for the impedance of free space, ε r ( ε r = ε ′ − jε″ ) represents complex permittivity, μ r ( μ r = μ′ − jμ″ ) stands for complex permeability, f stands for frequency, d is the thickness of MA materials, and c stands for the light speed.…”

Engineering Dielectric Loss of FeCo/Polyvinylpyrrolidone Core‐Shell Nanochains@Graphene Oxide Composites with Excellent Microwave Absorbing Properties

“…Currently, the fabrication of an efficient EMA material has evoked great attention, which means the material not only have strong adsorption and broad bandwidth but also light and thin at the same time. [ 7–9 ] To date, researchers are interested in fabricating novel EMA materials, including carbon, [ 10 ] silicon carbide, [ 11 ] zinc oxide, [ 12 ] MXene, [ 13 ] metal–organic framework (MOF), [ 14–16 ] etc.…”