Effect of gas atmosphere on the formation of silicon by reaction of SiC and SiO₂

The formation of silicon by reaction between quartz and SiC has been studied in the temperature range of 1600–1900 °C in argon and hydrogen atmospheres. The reaction process was monitored by an infrared gas analyzer, and the reaction products were characterized by LECO, XRD, and SEM. Quartz–SiC reactions with SiO₂/SiC molar ratio of 1:1 and 1:2 were studied in a fixed bed reactor in a graphite furnace. The production of silicon from quartz and SiC was strongly affected by temperature, SiO₂/SiC molar ratio, and gas atmosphere. The yield of silicon in the reaction at 1900 °C in argon from samples with SiO₂/SiC molar ratios of 1:1 and 1:2 reached 32.7 and 44.5 %, respectively. SiO₂–SiC reaction at 1900 °C in hydrogen with the SiO₂/SiC molar ratio of 1:2 resulted in the silicon yield of 66.7 %. Higher silicon yield in hydrogen was attributed for the involvement of hydrogen in the direct reduction of silica to SiO.