Influence of Water Vapor and Local Gas Velocity on the Oxidation Kinetics of In625 at 900 °C: Experimental Study and CFD Gas Phase Simulation

The effect of water vapor content on the oxidation behavior of In625 at 900 °C in synthetic air was reported. The higher the water vapor content, the greater the oxidation and volatilization rates were. Increasing the water vapor content led to an increase in the proportion of spinel and rutile-type oxides in the oxide scale compared to chromia, and the proportion of Al-rich oxides within the alloy. A k_p-k_v mass variation model was used to quantify the experimental results, and Fluent Ansys® CFD simulations of the gas phase were used to predict volatilization rates. CFD simulations were used to calculate local gas velocity, temperature and composition along with local volatilization rates at each point on the sample surface. It was possible to explain not only the variations in volatilization between upstream and downstream samples, but also the increased volatilization at sample corners. For longer durations, it was shown experimentally that the rate of volatilization decreases. This was explained by the enrichment of the oxide scale with spinel and rutile-type oxides.