Synthesis and Structural Characterization of Core-Shell Si-SiC Composite Particles by Thermal Plasma In-Flight Carburization of Silicon Powder

Unique core-shell-structured micron spheres of Si-SiC consisting of a layer of silicon carbide nanocrystallites and a silicon single-crystal core were synthesized by thermal plasma in-flight carburization of silicon micron powders in Ar-H2-CH4 plasma. Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX) revealed the formation of silicon carbide particles on the surface of Si particles, and transmission electronic microscopy (TEM) showed a uniform distribution of SiC nano-sized grains (~80 nm) at a depth of 500 nm beneath the surface of the composite spheres. Micron voids and nano pores were observed at the SiC-Si interface and in the Si matrix. The formation of long and thick SiC nanotubes was observed in the Si matrix near the SiC-Si interface. The mechanism of carburization reactions and the growth of silicon carbide layers and SiC nanotubes are discussed.