Improvement of SiC nanopowder synthesis by sol–gel method via TEOS/resin phenolic precursors

Abstract

In the present study, silicon carbide powder with the particle size lower than 50 nm has been synthesized by sol–gel method using the four-component system of alcohol–alkoxide–dispersant–resin in acidic conditions. The most significant parameters investigated in the current research include: pH, APC (ammonium polycarboxylate) dispersants, process temperature and soaking time. Sol–gel processing was performed in an alcoholic system as the averaged particle size in acidic pH ranges was found to be lower than 10 nm. Adding ammonium polycarboxylate resulted in stability of precursors within the sol via rendering electrosteric mechanisms. Powder properties were characterized using various analyses as: nuclear magnetic resonance, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). XRD analysis revealed the presence of cubic β-SiC phase, while the FE-SEM images confirmed that a longer synthesis time could lead to a morphological variation from spherical shapes to whisker. TEM/HRTEM images as well as their diffraction pattern verified the synthesis of carbide crystalline particles with size of less than 50 nm. HRTEM images of synthesized particles demonstrated ABCABC atomic arrangement, verifying their cubic structure in the form of β-SiC.