Porous SiC ceramic,; with a high specific surface area are promising candidates for catalyst support applications and further fabrication of nanowire-reinforced composites. This study employed the carbothermal reduction process using a mixed powder bed consisting of low-purity SiO2 and carbon black in order to grow SiC nanowires on phenolic resin-coated porous SiC ceramics. A nanowire grown at 1400 degrees C in the absence of a metal catalyst additionally introduced from the outside had a diameter of 100 nm and a length of several tens of micrometres. The carbothermal reduction method for growing SiC nanowires on surfaces as well as inner pores of porous SiC substrates involves migration and liquid droplet formation of elemental Fe generated from the mixed powder bed into the surface and the pores of the SiC substrate. Subsequently, gaseous SiO and CO from the mixed powder bed as the intermediate for 1-dimensional SiC were offered to the neighborhood of the porous substrate, and then the growth of beta-SiC nanowires on alpha-SiC substrate occurred via a VLS mechanism.

Keywords: silicon carbide; porous ceramics; nanowires; carbotherrmal reduction; powder bed technique