SILICA TO SILICON - KEY CARBOTHERMIC REACTIONS AND KINETICS

The primary carbothermic reactions for the reduction of silica to produce silicon were defined and the reaction kinetics were determined. Most possible reactions between silicon oxide and carbon or carbon compounds were studied by a series of thermogravimetric analyses at temperatures up to 2000°C. Four key sequential reactions occur with SiC and SiO as intermediate reactants; two reactions involve SiO2 and two involve SiO. Reaction rate versus temperature, activation energy, and preexponential factors were determined for each of six reactions involving SiO2 or SiO. These kinetic studies show that SiO, when combined with either carbon or Sic, reacts in the gaseous state, and the sublimation of SiO is not the rate‐limiting reaction for forming silicon. Copyright © 1990, Wiley Blackwell. All rights reserved