SiCN ceramics with controllable carbon nanomaterials for electromagnetic absorption performance

Abstract

Different kinds of carbon nanomaterials, free carbon (C free ), graphene, and Ncontaining graphene (NG), in single-source-precursors-derived SiCN ceramics, were in situ generated by modifying polysilazane with divinylbenzene, dopamine hydrochloride and melamine, respectively. Adjusting the carbon source brings phase structure and electromagnetic wave absorption (EMA) properties differences of SiCN/C ceramics. In situ C free enhances the EMA capacity of SiCN ceramics by improving their electrical conductivity of 9.2 × 10 −4 S/cm. The electrical conductivity of SiCN ceramics with 2D graphene sheets balloons to 2.5 × 10 −3 S/cm, causing poor impedance match thus leading to a worse EMA performance. In situ NG in SiCN ceramics has a low electrical conductivity of 5.6 × 10 −8 S/cm, making for excellent impedance match. The corrugated NG boosts dielectric loss, interfacial, and dipole polarization. NG-SiCN nanocomposites possess an outstanding EMA performance with RL min of −61.08 dB and effective absorption bandwidth of 4.05 GHz, which are ∼2.4 times lower and ∼4 times higher than those of SiCN, respectively.

Synthesis of (WZrNbTaM)C (M = Cr, Ni, Ti) ceramic powders and the electromagnetic wave absorption in 2–18 GHz

“…To achieve this, either increasing the proportion of microwave entering the material or enhancing the loss inside depends on EM parameters. Therefore, the study of absorbing materials is essentially to optimize the EM parameters of materials by adjusting their composition and structure, so as to enhance their absorption and loss effects on EM wave 57,58 . Figure 5 shows the real and imaginary parts of permeability and the tangent of the magnetic loss angle.…”

“…Therefore, the study of absorbing materials is essentially to optimize the EM parameters of materials by adjusting their composition and structure, so as to enhance their absorption and loss effects on EM wave. 57,58 Figure 5 shows the real and imaginary parts of permeability and the tangent of the magnetic loss angle. The real part of the permeability (𝜇 ′ ) indicates storage capacity.…”

Polymer-derived silicon oxycarbonitride bowls with hollow structures and hetero-nanodomains for electromagnetic wave absorption

“…5,6,11 Compositionally, PDCs with increased levels of free carbon and dielectric phases have been developed through managing pyrolysis conditions, 12 and employing a molecular approach with carbon-rich or metal-containing precursors. [13][14][15][16][17] For example, Yu et al reported a silicon oxycarbide nanocomposite with carbon nanotubes and cobalt silicide via a single-sourceprecursor derived ceramic method. This approach leverages the interactive contributions of both dielectric and magnetic losses.…”