Facile synthesis of SiOx spheres or dumbbell-shaped β-SiC whiskers on expanded graphite by silicon vapor deposition

Abstract A facile method was developed to synthesize SiO x spheres or dumbbell-shaped β-SiC whiskers on expanded graphite (SiO x /EG or β-SiC/EG) by silicon vapor deposition without catalyst. With the carbon black atmosphere, the above hybrids were synthesized above 1100 °C in a graphite crucible where silicon powder was placed under the expanded graphite (EG). The growth of SiO x spheres is controlled by vapor-solid mechanism at 1100 °C and 1200 °C. Namely, the active carbon atoms absorbed SiO (g) and Si (g) to form SiC nuclei. Then, the SiO 2 , residual SiO (g) and Si (g) deposited on SiC nuclei to form SiO x spheres. At 1300 °C and 1400 °C, the same SiO x spheres formed on EG as well as many dumbbell-shaped β-SiC whiskers. The growth of dumbbell-shaped β-SiC whiskers is controlled by vapor-vapor and vapor-solid mechanism successively. In a word, firstly, the β-SiC whiskers with defects formed via the reaction between Si (g) and CO (g). After that, the SiO 2 , residual SiO (g) and residual Si (g) preferentially deposited on defects, then deposited on other parts of β-SiC whiskers to form dumbbell-shaped SiC whiskers.