Synthesis of nanostructure silicon carbide whiskers by VLS mechanism

In this research by carbothermal reduction process and VLS mechanism, silicon carbide whiskers were produced. Pitch and silica by product of a manufacturer (as an inexpensive material) and ferrosilicon (as catalyst) were used as starting materials. Primary mixtures were synthesized at 1300°C and 1400°C in tube furnace under the argon atmosphere. The products were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns indicated the presence of SiC in the reaction products. The SEM analysis showed that SiC whiskers have been obtained. The SiC crystallite sizes were less than 50 nm. In the next step, primary mixtures were milled in a planetary ball mill at 5hr milling time. The activated powders were synthesized at 1400°C. The XRD patterns showed that by milling the starting materials, the peaks width was increased while their intensity decrease and it showed a reduction of about 5-10 nm in crystallite size, which shows more nucleation or faster growth of SiC whiskers.