Microwave-Assisted Synthesis of Layered SiC From Layered Precursors and Investigation of Its Microwave Absorption Properties

This article reports a microwave-assisted technique using an innovative layered precursor for the synthesis of layered silicon carbide (SiC), its formation mechanism and electromagnetic wave (EMW) absorption properties. The layered precursor with alternating “silicon-carbon” layers, by utilizing flake graphite and a Si/SiO 2 powder mixture as the carbon and silicon sources, respectively. The selective heating nature of microwaves enabled the precise control over an internal temperature gradient within the material. The influence of the C/Si molar ratio (varied as 1:1,1.5:1, 2:1, 2.5:1, and 3:1) on the microstructure and the EMW absorption properties of the resulting SiC was systematically studied. The product was identified as β -SiC, exhibiting a distinct layered structure with abundant interlayer porosities. An optimal EMW absorption was achieved at a C/Si = 2:1. A 1.7 mm thick film showed a minimum reflection loss (RLmin) of −42.15 dB at 16.38 GHz, with an effective absorption bandwidth (EABmax) of 6.21 GHz (11.79–18 GHz), which fully covers the entire Ku-band. This superb performance has been attributed to the unique hierarchical porous architecture, which facilitates efficient EMW absorption through optimized impedance matching and enhanced attenuation via multiple loss mechanisms. This work provides a novel strategy for synthesizing high-performance SiC-based EMW absorbers.