In Situ Growth of Core–Sheath Heterostructural SiC Nanowire Arrays on Carbon Fibers and Enhanced Electromagnetic Wave Absorption Performance

Abstract

Large-scale core-sheath heterostructural SiC nanowires were facilely grown on the surface of carbon fibers using a one-step chemical vapor infiltration process. The as-synthesized SiC nanowires consist of single crystalline SiC cores with a diameter of ∼30 nm and polycrystalline SiC sheaths with an average thickness of ∼60 nm. The formation mechanisms of core-sheath heterostructural SiC nanowires (SiC) were discussed in detail. The SiC-CF shows strong electromagnetic (EM) wave absorption performance with a maximum reflection loss value of -45.98 dB at 4.4 GHz. Moreover, being coated with conductive polymer polypyrrole (PPy) by a simple chemical polymerization method, the SiC-CF/PPy nanocomposites exhibited superior EM absorption abilities with maximum RL value of -50.19 dB at 14.2 GHz and the effective bandwidth of 6.2 GHz. The SiC-CF/PPy nanocomposites in this study are very promising as absorber materials with strong electromagnetic wave absorption performance.

Electromagnetic wave absorbing properties of glucose‐derived carbon‐rich SiOC ceramics annealed at different temperatures

“…29,30 The determined absorption properties of the glucose-SiOC ceramics mainly depend on the relative complex permittivity. Therefore, the relative complex permittivity (ε r = ε′−jε″) and permeability (μ r = μ′−jμ″) were recorded by the vector network analyzer.…”

“…One should emphasize that the relative permittivity in this work is regarded as one considering lacking of the magnetic one in such nanocomposite. 29,30 The determined absorption properties of the glucose-SiOC ceramics mainly depend on the relative complex permittivity. Figure 6 shows the real (ε′) and imaginary (ε″) part of the relative complex permittivity, the dielectric tangent loss (tanδ = ε″/ε′) and the ε′-ε″ curves of the nanocomposites in 2-18GHz.…”

Retracted Article: The influence of gradient and porous configurations on the microwave absorbing performance of multilayered graphene/thermoplastic polyurethane composite foams

“…The serious electromagnetic (EM) irradiation caused by the widespread application of wireless telecommunication devices has concerned the whole society, due to it has danger to human health as well as issues with communication security. [1][2][3][4][5][6][7][8] Carbon materials, such as carbon nanotubes, [9][10][11][12] carbon bers [13][14][15][16] and graphene, 4,6,[17][18][19][20][21][22] possess good electrical conductivity and dielectric performance, and thereby are usually employed in polymer matrices to fabricate microwave absorbing materials (MAMs), owing to their superior properties including mechanical exibility, light weight, corrosion resistance and excellent processability. [23][24][25] Aer bringing porous structures into polymeric MAMs, such materials can be further processed into composite foams.…”

Enhanced electromagnetic wave absorption of Fe‐doped silicon oxycarbide nanocomposites

“…Lastly, Debye dipolar relaxation plays an important role for the EMI absorbing performance. According to the Debye theory, ε ″ can be described as follows:where ε s is the static permittivity, ε ∞ is the relative dielectric permittivity at the high‐frequency limit, ω the angular frequency, τ is the relaxation time, and σ is the electrical conductivity. Therefore, increasing the conductive paths could improve the permittivity according to the Equation ().…”