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)S_x/(CrFe)₃S₄/-(FeCr)S_x scale was formed at high sulfur pressures (range I), a single-phase (FeCr)S_x or a duplex (CrFe)S_x/(FeCr)S scale at intermediate sulfur pressures (range II), and a single-phase (CrFe)S_x 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${\text{P}}_{S_2 }$.