Hb. Qi et al., THE SULFIDATION PROPERTIES OF TITANIUM-BEARING MANGANESE-BEARING AND NIOBIUM-BEARING FE-25CR ALLOYS IN H2-H2S MIXTURES AT 800-DEGREES-C, Corrosion science, 35(5-8), 1993, pp. 1099-1105
An investigation of high-temperature sulphidation properties of 4 wt%
Ti-, 9 wt% Mn- and 8 wt% Nb-bearing Fe-25Cr alloys has been carried ou
t in H-2-H2S mixtures of sulphur partial pressure in the range of 10(-
3) < pS2 < 1 Pa at 800-degrees-C. On the whole, the sulphidation kinet
ics of all alloys obeyed the parabolic law after the initial period of
reaction. In some cases, fluctuations in the weight gain-time curves
arose due to cracking of sulphide scales. Compared with the weight gai
n of Fe-25Cr alloy, the additions of alloying elements improved the su
lphidation resistance. The effect of 8 wt% Nb was relatively major. bu
t the effects of 4 wt% Ti and 9 wt% Mn were minimal. The addition of t
hese elements did not change the surface morphologies or improve the s
tructure of sulphide scales. Combining the sulphidation kinetics and t
he analysis of sulphide scale structure, the sulphidation mechanisms o
f these Fe-25Cr-base alloys have been proposed and the effects of tita
nium, manganese and niobium have been discussed.