High Temperature Corrosion Behaviour of T-91 and T-22 Bare Steel in 75wt.%Na₂SO₄+25wt.%NaCl Molten Salt Environment at 900°C

Abstract

The oxidation behaviour of T-91 steel and T-22 steel in salt of 75wt.% Na 2 SO 4 +25wt.% NaCl has been studied under isothermal conditions at a temperature of 900°C in a cyclic manner. Oxidation kinetics was established for the T-91 steel and T-22 steel in salt at 900°C under cyclic conditions for 50 cycles by thermogravimetric technique. Each cycle consisted of 1 hour heating at 900°C followed by 20 min of cooling in air. Both the samples nearly followed the parabolic rate law of oxidation. X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray (SEM/EDAX) techniques were used to characterise the oxide scales. T-91 steel was found to be more corrosion resistant than T-22 steel under salt oxidation.