High Yield Silicon Carbide Whiskers from Rice Husk Ash and Graphene: Growth Method and Thermodynamics

A new stacking bed method to prepare high-quality silicon carbide whiskers (SiCws) with high yield has been proposed. To provide a steady and high concentration SiO atmosphere during the carbothermal reaction, the mixture of graphene and rice husk ash is used as a SiO generator, which is different from the traditional methods using sole silicon sources. The as-prepared whiskers, growing along the direction of [111], show a diameter of 30-120 nm. SiCws obtained by the optimized approach exhibit a higher stacking fault (SF) density. As indicated by thermal gravimetric mass spectrometry results, SiO gas is a key factor affecting the yield and SFs of SiC whiskers. Furthermore, combined with the chemical reaction thermodynamics, the growth mechanism of whiskers is presented following the vapor-solid mode. This contribution provides new insights into the industrial production of high value-added carbide whiskers.