Experimental investigation of silicon carbide rod-like structures obtained by drying droplet and autoclave methods

Preparation of silicon carbide by traditional methods involves considerable energy and economic costs, so the search for alternative technologies of the synthesis is of the great interest. Carbon nanomaterials are actively investigated as a carbon source to reduce the temperature of synthesis. This paper presents the results of an experimental study of the morphology, elemental composition and crystal structure of structures obtained from colloidal solutions of short (l ~ 500 nm) carbon nanotubes and nano-sized (~ 7 nm) amorphous silicon dioxide by drying droplet and autoclave methods. The formation of rod-like structures was revealed at certain critical concentrations of initial components. It was found that the dynamic conditions of the drying droplets determine a synthesis of rod-like structures at room temperature at 2-3 times larger than at the autoclave at a temperature of about 180 °C. The elemental analysis of samples showed a high percentage of carbon and silicon atoms. The presence of the polytype 4-H SiC phase in the rod-like structures was revealed by the X-ray diffractometry. A model of the active charged center of short carbon nanotubes that provides the possibility of Si-C, Si-O-C and C-Si-O-C covalent bonds formation was offered based on numerical calculations. The drying droplet method is suitable for a quick (10-20 minutes) local synthesis of a small amount of rod-like structures with a minimum energy consumption. The autoclave allows to synthesize gram quantities for a long time (a few days). Both methods are low temperature in the comparison with the widely used in practice.