The effect of thermal annealing on the properties of thin alumina films prepared by low pressure metal-organic chemical vapour deposition

摘要

Thin amorphous alumina films were prepared on stainless steel, type AISI 304, by low pressure metal-organic chemical vapour deposition. The effect of thermal annealing in nitrogen (for 2, 4 and 17 h at 600, 700 and 800 °C) on the film properties, including the protection of the underlying substrate against high temperature corrosion and the chemical composition of the film, were investigated. Corrosion experiments performed at 450 °C in a hydrogen sulphide-containing gas, showed that the thermal annealing process had a detrimental effect on the protective properties of the alumina films. From FTIR and Auger measurements, it was found that the amorphous alumina, containing boehmite, converted to ¿-alumina during the annealing process.