SiO2+SiC reaction at elevated temperatures. Part 2.—Effect of added gases

The rate of reaction between silica and silicon carbide is depressed by added gases. With inert gases this depression is a function of the molecular weight and pressure of the gas. A model to describe the effect is given in terms of Fickian diffusion. With gases which chemisorb on the silicon carbide surface the rate depression is much greater than with inert gases. The reaction rate is described in terms of an adsorption isotherm which takes into account dissociation of the adsorbing molecule. The strength of the surface bond formed is in the order NO>HCl>Cl2>CO>N2.