Synthesis of SiC Powders by Carbothermal Reduction of Enriched Brown Sepiolite with Carbon Black

摘要

Ultrafine β-silicon carbide (β-SiC) powders were successfully synthesized by carbothermal-reduction reaction (CRR) of sepiolite. Sepiolite of Turkish deposits as a silica (SiO_2) precursor and carbon black as a reducing agent were mixed with constant C/SiO_2 molar ratio of 4. Mixed powders were subjected to CRR at temperatures of 1450, 1500, and 1550℃ for 1 h in an atmosphere-controlled tube furnace under argon flow of 5 cm~3/min. The precursor and resultant powder products were characterized by XRD, SEM, and EDX. Phase transformation was observed in powder products after CRR as a function of the reaction temperature. The results show that the cotton-like nature of sepiolite makes it an effective mineral precursor for synthesis of SiC powders, and that SiC transformation was optimized at 1550℃ with a particle size of approximately 200 nm.