3D modeling of a microwave post-discharge nitriding reactor

A 3D model has been developed for a post-discharge microwave nitriding reactor. It enables prediction of the hydrodynamics of the gas, together with the distribution of atomic nitrogen mass fractions, representing the map of the active nitriding species, and the temperature distribution inside the reactor. The coupled transport equations are solved using the PHOENICS calculation code. The model has been used to simulate the phenomena occurring in the gas phase during the nitriding of three pure iron rods placed in the reactor. The optimum nitriding conditions were determined by optical emission spectroscopy and N atoms titration by NO. Under these conditions, numerical validation of the model was performed by comparison with experiments, using a second solid-state diffusion model to evaluate the interaction between the solid and gas phases. (C) 1997 Elsevier Science S.A.