Synthesis and characterization of nanostructured silicon carbide crystal whiskers by sol–gel process and carbothermal reduction

Abstract

Silicon carbide whisker is a promising reinforcement material for metal and ceramic matrix composites. In this paper, nanostructured β-SiC whiskers were synthesized from an organic–inorganic hybrid precursor via a carbothermal reduction of silica by carbonized phenolic resin. The organic–inorganic hybrid precursor for the carbothermal reduction was synthesized by gelating the mixture of water soluble phenolic resin and silica sol. The products after the carbothermal reduction were characterized by X-ray Diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The results show that the products synthesized at 1500–1700°C are highly ordered and pure β-SiC crystal whiskers with diameters of 30–150nm. The microstructure of whiskers changes with the variation of the reaction temperature. Interestingly, threaded rod shaped SiC whiskers were obtained at 1600°C. The growth of SiC crystal whiskers at different temperatures is controlled by different reaction kinetics. The solid–solid reaction is the dominat kinetics in the carbothermal reduction, with solid–gas reaction and gas–gas reaction as the additional reaction kinetics.