Fluid dynamic simulation of CrO2(OH)2 volatilization and gas phase evolution during the oxidation of a chromia forming alloy

The influence of the chromia volatilization on the oxidation kinetics of Inconel 625 was investigated at 900 ◦C under flowing wet air (74%N2-18.5%O2-7.5%H2O) through an interdisciplinary approach, coupling experiments and gas phase simulation. Oxidation tests showed a strong decrease in the volatilization rate of lined-up samples from the inlet to the outlet of a horizontal tubular furnace. Gas phase simulation allowed to relate it to an increase in the CrO2(OH)2 partial pressure along the tube. Considering gas composition changes appears as essential to provide correct interpretation of oxidation test results in humid and oxidizing environments