The effects of aluminum alloying additions on the sulfidation behavior of iron.

As part of an overall research program to examine the possible development of sulfidation-resistant alloys, the corrosion behavior of binary iron-based alloys containing 5, 10, and 20 wt. % of aluminum has been studied in a hydrogenhydrogen sulfide atmosphere for the temperature range 800-1000°C. Details of the observed overall reaction kinetics, the scaling kinetics, and the scales' morphology and composition are given. By considering these results in relation to those reported in an earlier paper concerning the sulfidation of an iron- 5 wt. % aluminum alloy at a lower temperature range, 500-700°C, it has been possible to ascertain the usefulness of aluminum as an alloying addition whereby the sulfidation resistance of iron might be improved. It is concluded that although aluminum can be quite effective in this context at relatively low reaction temperatures at only the 5 % concentration level, at the elevated temperatures likely to be of more industrial importance its usefulness is not maintained, even at the 20% level. The possible reason(s) for the inferior high-temperature performance of these alloys are discussed. [ABSTRACT FROM AUTHOR]