Characterization of SiC Whiskers from Rice Husks in Argon Atmosphere

Abstract

SiC whiskers were prepared through carbonthermal reduction in two steps. Firstly raw rice husks (RHs) were pyrolysed in a graphite vacuum furnace at 460°C for 2 hours and coked rice husks were pyrolysed at 1400°C in argon atmosphere. Scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) was employed to characterize the morphology and phase composition of SiC whiskers. The results show that the diameters of SiC whiskers range in 20-200 nm and their lengths are in the range from hundreds of microns to several millimeters. The whiskers are straight and slightly rough and consist of β-SiC crystals with bamboo-like structure. Vapor-solid (VS) mechanism plays a key role at the early stage of SiC formation and VLS mechanism and vapor phase mechanism of the whiskers are involved during the growth of SiC whiskers.