Fabrication and mechanism of 6H-type silicon carbide whiskers by physical vapor transport technique

In this paper, silicon carbide whiskers (SiCw) were fabricated by the physical vapor transport (PVT) technique at 2293 K with Fe as the catalyst. X-ray diffraction, scanning electronic microscope, energy-dispersive X-ray spectroscopy and transmission electron microscopy were used to identify the phase formation and morphology of the SiCw. The results showed that 6H-SiCw with growth direction of [0001] were obtained with the diameters ranging from 0.2 μm to 4 μm, and the length up to 700 μm. The whiskers appeared as a cluster characteristic on the activated carbon fiber. Meanwhile, the catalyst ball at the tip of each whisker indicated the vapor–liquid–solid growth mechanism for 6H-SiCw.The growth mechanism was investigated on the basis of the physical and chemical phenomena during the PVT growth process of SiCw. It was found that high temperature guaranteed the evaporation of raw materials to form the catalyst, Si- and C-containing vapor specials and promoted the nucleation and growth of 6H-SiCw. Finally, a growth model was proposed.

► 6H-type silicon carbide whiskers were fabricated by the physical vapor transport technique. ► Fe served as the catalyst. ► No 6H-SiCw could be fabricated without Fe powder in the raw materials. ► Design of the crucible lid also played an important role in the nucleation of SiCw.