Oxidation, sulfidation and hot corrosion of intermetallic compound Fe 3Al at 605°C and 800°C

Abstract

Oxidation, mixed oxidation–sulfidation and hot corrosion of ductile iron aluminide Fe 3Al with Cr addition have been examined at temperatures of 605°C and 800°C. It is observed that Fe 3Al–5Cr specimen tested at 605°C a small amount of island-like Fe 2O 3 was formed on the specimen surface. Since the oxidation temperature was relatively low, the thin oxide film on the surface could not be detected by X-ray diffraction analysis. However, at 800°C the needle-shape Al 2O 3 surface morphology was produced both in air and 1% SO 2/air environment. Hot corrosion of iron aluminide is significantly more severe than oxidation and mixed oxidation–sulfidation. This can be attributed to possibly the following two factors. First, aluminide sulfide is formed at the interface of metal-salt, as a result of high sulfur potential in molten salt at the oxide–metal interface. Second, since the molten salt covers the specimen surface, the supply of oxygen through molten salt is much faster than the diffusion through solid oxide layer. Therefore, an accelerated oxidation–sulfidation occurs under the hot corrosion condition.