Sulfidation properties of an Fe-26.6 at.% Cr alloy at temperatures of 973?1173 K in H2S-H2 atmospheres at sulfur Pressures 104?10?6 Pa

Abstract

An investigation is reported on the sulfidation properties of an Fe-26.6 at. % Cr alloy at 973, 1073, and 1173 K in H2S-H2 atmospheres at sulfur pressures 104⩾\({\text{P}}_{S_2 } \) ⩾10−6 Pa. The sulfidation kinetics when plotted according to a parabolic relationship usually exhibited an early slow transient period before onset of parabolic kinetics. Scales contained up to three layers. A triplex (CrFe)Sx/(CrFe)3S4/-(FeCr)Sx scale was formed at high sulfur pressures (range I), a single-phase (FeCr)Sx or a duplex (CrFe)Sx/(FeCr)S scale at intermediate sulfur pressures (range II), and a single-phase (CrFe)Sx scale at low sulfur pressures (range III). These pressure ranges at 973 K were: range I ⩾\({\text{P}}_{S_2 } \) = 10−2Pa, 10−2 >\({\text{P}}_{S_2 } \) (range II) ⩾ 10−5 Pa, and range III\({\text{P}}_{S_2 } \).