Corrosion resistance of iron aluminides

摘要

Iron aluminides are being developed for use as structural materials and/or cladding alloys in fossil energy systems. Extensive development has been in progress on Fe(sub 3)Al-based alloys to improve their engineering ductility. This paper describes the corrosion performance of these alloys, determined at Argonne Naitonal Laboratory, in environments that simulate coal gasification and fluidized-bed combustion. Thermogravimetric analysis (TGA) was conducted at temperatures of 650--1000(degrees)C in air, 1 vol. % CO-CO(sub 2), and H(sub 2)-H(sub 2)S environments at two sulfur activities. Upon completion of the kinetic runs, the morphology and structure of the scales formed on the alloy surface were evaluated by scanning electron microscopy and energy-dispersive X-ray analysis. Corrosion tests in simulated combustion environments were conducted at 900(degrees)C in the presence of reagent-grade CaSO(sub 4) and circulating-fluidized-bed deposits for 1000 and 3000 h. The test data on the aluminides from the TGA and combustion tests were compared with the corrosion performance of Type 310 stainless steel tested under similar conditions.