High temperature oxidation of silica formers in dissociated oxygen

Abstract

A study of the high temperature oxidation of silica formers in dissociated oxygen is presented in this dissertation. Flowing an O2/Ar gas mixture through a microwave discharge before it entered a flow reactor generated the partially dissociated oxygen environment. The samples were oxidized at high temperatures (1183 K – 1323 K) and low pressures (3 Torr – 4 Torr). The O atom concentration near the sample surface, determined using a semi-empirical reactor model, was used to define the quantitative role of O atoms in the oxidation mechanism. The continuous, non-isothermal, compressible, laminar flow, coupled with high-temperature oxygen plasma afterglow chemistry model was solved using the finite element method. Modeling of the silicon, Si3N4, and SiC oxidation mechanisms showed that the O atom is the dominant oxidizing species, with O2 having a negligible effect.