SiC–Si3N4 composite with multi-laminate nanowires originated from oriented porous structure by freeze-casting

Abstract

Novel form of SiC–Si3N4 composite has been prepared via a simple and versatile route, namely carbon-doped sol with aligned pores from freeze casting method in combination with the subsequent carbothermal reduction process. The oriented pores of green bodies supply both nitrogen and space for the nucleation and growth of Si3N4 nanowires following the VS mechanism. Meanwhile, lack of nitrogen at partial region leads to the generation of aggregated β-SiC particulates. As a result, multiply laminate nanofibrous ceramic foams embedded with fine particles have been prepared. Owing to the low bulk density of 0.15 g/cm3 and fine building blocks, this novel material possesses relatively high specific surface area of 29.89 m2/g and ultra-low thermal insulation of 0.058 W/(m·K), which would have potential applications in the catalysts, thermal insulators or gas/liquid filters fields.