SiO2+SiC reaction at elevated temperatures. Part 1.—Kinetics and mechanism

Abstract

The reaction between finely divided SiO₂ and SiC at 1270–1430°C was studied. The reaction scheme proposed is: 2SiC+SiO₂= 3Si_a+2CO_a 2Si_a+CO = SiO_a+SiC Si_a+SiO₂= 2SiO_a Si_a, SiO_a, CO_a= Si_g, SiO_g CO_g. During the first 2–6% of reaction, Si volatilizes; thereafter primarily SiO and CO volatilize. Only the upper layers of the charge contribute to the net forward reaction rate, hence the state of reactant subdivision is of secondary importance. An Arrhenius plot of the reaction in vacuo gives an apparent activation energy of 131–97 kcal/mole in the range 1270–1430°C. The rate-determining step is desorption of products from the SiC surface.