Formation of nanocrystalline SiC powder from chlorine-containing polycarbosilane precursors

Nanocrystalline beta-SiC particulates with a grain size range of 5-20 nm were prepared by heating a pre-pyrolyzed, chlorine-containing polysilane/polycarbosilane (PS/PCS) to 1600 degrees C. The transformation from the pre-pyrolyzed PS/PCS to nanocrystalline SiC was investigated by differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD), mass-spectrometry and infrared spectroscopy. The results indicated that the nanocrystalline beta-SiC was formed by the crystallization of the PS/PCS random network, and crosslinking of Si-Si, Si-CI, and Si-CH2-Si bonds. The TEM observation showed that SiC particulates consist of equiaxed, randomly oriented, ultrafine grains.