Microcellular SiC foams containing in situ grown nanowires for electromagnetic interference shielding

Microcellular SiC foams (MSiCFs) are produced by thermal setting of dispersions of silicon and NaCl powders in molten sucrose-glycerol solutions in a mould followed by carbonization, NaCl removal and reaction bonding at 1500 degrees C. The acidic silica layer on silicon particle surface catalyses the setting of the pastes by -OH condensation. The SiC nanowires grown in situ by a catalyst-free vapour-solid (VS) mechanism creates web-like architecture within the microcells (cell size -2 to 22 mu m) of the foams. The MSiCFs with porosity in the range of 86.8-91.1 vol.% exhibit thermal conductivity and compressive strength in the ranges of 0.334-0.758 W m(-1) K-1 and 0.97-2.38 MPa, respectively. The MSiCFs show excellent electromagnetic interference (EMI) shielding property in the X-band frequency region enhanced by the in situ grown SiC nanowires within microcells. The EMI shielding effectiveness (45.6 dB) and specific shielding effectiveness (137 dB g(-1) cm(3)) are the highest reported for SiC foams. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.