Light and Strong Hierarchical Porous SiC Foam for Efficient Electromagnetic Interference Shielding and Thermal Insulation at Elevated Temperatures

Abstract

A novel light but strong SiC foam with hierarchical porous architecture was fabricated by using dough as raw material via carbonization followed by carbothermal reduction with silicon source. A significant synergistic effect is achieved by embedding meso- and nanopores in a microsized porous skeleton, which endows the SiC foam with high-performance electromagnetic interference (EMI) shielding, thermal insulation, and mechanical properties. The microsized skeleton withstands high stress. The meso- and nanosized pores enhance multiple reflection of the incident electromagnetic waves and elongate the path of heat transfer. For the hierarchical porous SiC foam with 72.8% porosity, EMI shielding can be higher than 20 dB, and specific EMI effectiveness exceeds 24.8 dB·cm·g at a frequency of 11 GHz at 25-600 °C, which is 3 times higher than that of dense SiC ceramic. The thermal conductivity reaches as low as 0.02 W·m·K, which is comparable to that of aerogel. The compressive strength is as high as 9.8 MPa. Given the chemical and high-temperature stability of SiC, the fabricated SiC foam is a promising candidate for modern aircraft and automobile applications.

Monolithic silicon carbide with interconnected and hierarchical pores fabricated by reaction‐induced phase separation

“…Porous silicon carbide (SiC) monoliths attract increasing attentions in catalyst/catalyst support, electromagnetic absorption, heat exchanger, hot gas separation, porous media combustion, and metal/ceramic composite areas, owing to their excellent properties including high‐temperature stability, good mechanical strength, low thermal expansion coefficient, high thermal conductivity, and chemical inertness. In light of their promising applications, numerous methods have been developed for the fabrication of porous SiC monoliths, such as oxidation bonding, freeze‐drying, sacrificial templating, direct foaming, and sol‐gel method combined with carbothermal reduction.…”

Suppressing Electromagnetic Radiation by Trapping Ferrite Nanoparticles and Carbon Nanotubes in Hierarchical Nanoporous Structures Designed by Crystallization‐Induced Phase Separation

“…However, EM waves penetrate through the composite wherein, waves get interacted with the trapped nanoparticles + MWNTs present in the composites. This leads to the magnetic and ohmic losses resulting in resulting in dissipation of EM waves and energy absorption of EM waves ,. The surviving EM waves penetrate in the polymer composites containing 3 wt% MWNTs and phenomena of EM waves attenuation repeats.…”

Nanowire‐decorated SiC foam from tissue paper and silicon powder by filter‐pressing

“…Silicon carbide (SiC) foams have a number of unique characteristics such as low density, low thermal conductivity, controlled permeability, high surface area, high thermal shock resistance, high specific strength, good oxidation resistance, and ability to absorb electromagnetic waves . These unique characteristics make them suitable for application as a thermal shield in aerospace, light‐weight structural component for high‐temperature applications and electromagnetic interference (EMI) shielding at high temperature .…”

“…Liang et al reported a preparation of SiC foam from dough by carbonization followed by carbothermal reduction. They obtained SiC foams with hierarchical pore structure having a maximum porosity of 78% …”