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

[Display omitted] •Microcellular SiC foams were prepared by a simple and scalable method.•Web-like SiC nanowires are formed within the cellular voids and cell walls.•Thermal conductivity of the foams is in the range of 0.334–0.758Wm−1K−1.•Highest compressive strength of 2.38MPa is obtained at 86.9% porosity.•High EMI shielding effectiveness (45.6dB) and specific shielding effectiveness (137dBg−1cm3) are obtained. 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°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 22μm) of the foams. The MSiCFs with porosity in the range of 86.8–91.1vol.% exhibit thermal conductivity and compressive strength in the ranges of 0.334–0.758Wm−1K−1 and 0.97–2.38MPa, 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 (45.6dB) and specific shielding effectiveness (137dBg-1cm3) are the highest reported for SiC foams.