Oxidation--sulfidation behavior of iron--chromium--nickel alloys

Oxidation--sulfidation studies of Fe--Cr--8 Ni alloys with 4, 12, and 22 wt % Cr were conducted at 750 and 8750C in multicomponent gas mixtures that contained CO, CO2, CH4, H2, and H2S. The reaction processes resulted in parabolic kinetics. A chromium concentration in the range 0 to 12 wt % in the alloy had a negligible effect on the parabolic rate constant; however, the rate constant for the alloy with 22 wt % Cr was significantly lower. For a given sulfur partial pressure, the oxygen partial pressures required for the formation of a continuous oxide layer in an Fe--22Cr--8 Ni alloy were approx.102 to 103 times those calculated for Cr--Cr2O3 equilibrium at temperatures of 875 and 7500C, respectively