Corrosion Behavior of Hastelloy-XR Alloy in O_2 and SO_2 Atmosphere

摘要

As Hastelloy-XR alloy is a candidate structural material for the IS (Iodine-Sulfur) process in hydrogen production, oxidation and sulfidation of Hastelloy-XR alloy in Ar-O_2 and Ar-SO_2 atmospheres were studied by thermogravimetry at temperatures from 1000 to 1300 K. In Ar-O_2 atmosphere, the mass change obeyed a linear-parabolic law at oxygen partial pressures (Pq,) from 0.01 to 10kPa. The oxidation scales consisted of inner Cr_2O_3 layer and outer Mn_(1.5)Cr(1.5)O_4 spinel layer. The surface morphology of the oxide scales changed from island-like to buckled and to porous texture with decreasing Po,. In Ar-SO_2 atmosphere, the mass change obeyed a linear-parabolic law at SO_2 partial pressures (Pso,) from 0.05 to 5kPa. The morphology of corrosion scales changed mainly with corrosion temperature. While oxidation was dominant at 1073 and ] 173 K forming double-layer scales of inner Cr_2O_3 and outer Mn_(1.5)Cr_(1.5)O_4 spinel, sulfidation was accompanied with oxidation at 1273 K and PSo < 0.5 kPa with scales consisting of Fe_3O_4. FeCr_2O_4 and Cr_2O_3 layers and Ni3S2 dispersed particles together with CrS particles segregating at the grain boundary of Hastelloy-XR alloy.