Synthesis of silicon carbide from secondary silicon-containing materials

This study presents an experimental approach to the synthesis of silicon carbide (SiC) using technogenic and biogenic wastes—microsilica and rice husk. The synthesis was carried out by carbothermal reduction in a self-designed and constructed laboratory resistance furnace. The starting materials were subjected to preliminary mechanical activation in a planetary centrifugal mill, which enhanced their reactivity. The morphology and elemental composition of the samples were examined using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The results demonstrated the formation of characteristic SiC crystals and confirmed their composition, close to stoichiometric. X-ray diffraction analysis revealed the presence of β-SiC (3C) and hexagonal polytypes (4H, 6H-SiC), as well as secondary phases of silicon dioxide (cristobalite, tridymite), reflecting the specific features of the reaction at high temperatures. It was established that mechanical activation promotes more intensive SiC formation and reduces the amount of residual oxide phases. The obtained results confirm the potential of utilising secondary silicon-containing resources for SiC synthesis, which is significant for the development of environmentally oriented technologies and for expanding the raw material base for high-value-added materials.