▎ 摘　　要

SiC/multilayer graphene composite powders and SiC nanopowders (SiCNPs) were successfully synthesized via a simple catalyst-assisted carbothermal reduction method using silicon dioxide and expanded graphite. The influences of the catalyst content, heat treatment temperature, and graphite/SiO2 molar ratio on the synthesis of powders were studied. The phase composition and their relative content, morphologies, che-mical structures, and microstructures were detected using XRD, SEM, AFM, RAMAN, XPS, FTIR, BET, and TEM, respectively. Electromagnetic wave absorption properties of the products were studied at frequencies from 2 to 18 GHz. The results show that the introduction of Fe catalyst has a pronounced catalytic effect on the synthesis of 3 C-SiC powders. The formation temperature of 3 C-SiC is reduced to 1673 K with 0.5 wt% Fe addition as the catalyst. When the expanded graphite is appropriately excessive (the molar ratio of graphite/ SiO2 is 3.5), multilayer graphene with a thickness of about 3.5 nm is formed in-situ in the composite powders. The 3 C-SiC/multilayer graphene composite powders exhibit the optimal electromagnetic wave absorption property. When the filling ratio of 3 C-SiC/multilayer graphene composite powders is 30 wt%, the minimum reflection loss reaches - 53.62 dB at a thickness of 2.04 mm and a frequency of 13.95 GHz. Graphene has a unique internal microstructure, high dielectric loss and good conductivity, which improve the impedance matching of the material and then increase the magnetic loss. It is predicted that the SiC/ multilayer graphene composite powder has the potential to become an excellent electromagnetic wave absorber. (c) 2023 Elsevier B.V. All rights reserved.