Influence of Iron Oxides and Chlorides on the Corrosion of Stainless Steels and Ni-based Alloys in O_2-H_2O-HCl at High Temperatures

摘要

Corrosion of stainless steels, SUS304L, SUS310S, and Ni-based alloy, HastelloyC-276, covered with/without Fe_2O_3, FeCl_2 or FeCl_3 powder was investigated for 5 days in O_2-H_2O-HCl atmospheres at 160-210 deg C under heat transfer conditions. Corrosion rate of SUS304L and SUS310S was much higher than that of HastelloyC-276, and was enhanced considerably by covering with FeCl_3. The enhanced corrosion rate on the FeCl_3-covered specimen was due to the formation of concentrated FeCl_3/HCl solution by absorbing H_2O and HCl into FeCl_3. Corrosion mechanisms of stainless steels are discussed thermodynamically in terms of oxychlorination of iron.