The thermodynamics and the growth kinetics of synthesis of the SiC whiskers (SiC w ) from rice hulls are studied in this paper. The results show that the intimate contact of SiO 2 with C in the rice hulls resulted in ...The thermodynamics and the growth kinetics of synthesis of the SiC whiskers (SiC w ) from rice hulls are studied in this paper. The results show that the intimate contact of SiO 2 with C in the rice hulls resulted in the formation of SiC particle (SiC p ) at lower temperature, and the external ash of the hulls (w (SiO 2 )>98%) is the main silicon source for SiCw growth. The metallic composite catalyst increases the selectivity for SiCw growth and the reaction rate. The growth mechanism of the SiCw can be characterized as the VLS (vapour liquid solid) with the presence of the whisker forming catalyst: from SiC nucleation through enlargement and growing with the <1 1 1> crystallographic orientation in a certain diameter, then the SiC w is a complete single crystal of β SiC. The generation reaction of SiO is the rate determing step for synthesis of SiC w .展开更多
文摘The thermodynamics and the growth kinetics of synthesis of the SiC whiskers (SiC w ) from rice hulls are studied in this paper. The results show that the intimate contact of SiO 2 with C in the rice hulls resulted in the formation of SiC particle (SiC p ) at lower temperature, and the external ash of the hulls (w (SiO 2 )>98%) is the main silicon source for SiCw growth. The metallic composite catalyst increases the selectivity for SiCw growth and the reaction rate. The growth mechanism of the SiCw can be characterized as the VLS (vapour liquid solid) with the presence of the whisker forming catalyst: from SiC nucleation through enlargement and growing with the <1 1 1> crystallographic orientation in a certain diameter, then the SiC w is a complete single crystal of β SiC. The generation reaction of SiO is the rate determing step for synthesis of SiC w .
