Thin SiO2 films were heat treated in different gas mixtures to determine their stability in functioning as high-temperature hydrogen permselective membranes. The films were formed within the walls of porous Vycor tubes by SiH4 oxidation in an opposing reactants geometry. Film deposition was carried out at 450 °C in the presence and absence of water vapor. Immediately after formation, the films were highly selective to hydrogen permeation having a H2:N2 permeability ratio of about 3000:1. The films were subsequently heat treated at 450-700°C in dry N2, dry O2, N2-H2O, and O2-H2 mixtures. The permeation rates of H2 and N2 changed depending on the original conditions of film formation as well as on the heat treatment.
ASJC Scopus subject areas
- Chemical Engineering(all)