Effect of gas atmosphere on the formation of silicon by reaction of SiC and SiO.sub.2

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 SiO.sub.2/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, SiO.sub.2/SiC molar ratio, and gas atmosphere. The yield of silicon in the reaction at 1900 °C in argon from samples with SiO.sub.2/SiC molar ratios of 1:1 and 1:2 reached 32.7 and 44.5 %, respectively. SiO.sub.2-SiC reaction at 1900 °C in hydrogen with the SiO.sub.2/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.