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Sulphidation of the Fe‐40 at.% Al alloy in H 2 /H 2 mixtures at high temperatures
Author(s) -
Godlewska E.,
Roszczynialska E.
Publication year - 1997
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.19970480505
Subject(s) - alloy , electron microprobe , hydrogen , aluminium , materials science , chemical composition , sulfur , metallurgy , analytical chemistry (journal) , hydrogen sulphide , phase (matter) , atmospheric temperature range , chemistry , thermodynamics , environmental chemistry , physics , organic chemistry
Sulphidation of an ordered bee alloy having the nominal composition Fe‐40 at.% Al was studied at temperatures of 1073‐1273 K in hydrogen/hydrogen sulphide mixtures at sulphur pressures of 10 −5 – 10 −2 Pa. The sulphidation runs were followed thermogravimetrically. Phase and chemical composition of the sulphide scales and the scale morphologies were determined by means of XRD, EDX, EPMA and SEM. The sulphidation runs showed a relatively fast uptake of sulphur at the beginning followed by a gradual slowdown. The estimated parabolic rate constants for the second stage of the reaction were of the order of 10 −12 – 10 −11 kg 2 /m 4 s, i. e. comparable to the oxidation rates of alumina formers in the same temperature range. The initial faster growth of the sulphide scale was attributed to the formation of iron‐aluminum sulphospinel whereas the second stage to the development of aluminum sulphide at the alloy/scale interface.