Integral Diffusion Model of the Kinetics of Growth of Nitrided Layer in Gas Nitriding of Armco Iron

The kinetics of gas nitriding of Armco iron is studied using an integral diffusion model. A system of differential equations is used to calculate the thickness of the diffusion layers of epsilon- and (epsilon + gamma ')-phases on the surface of saturated armco iron. The calculations do not allow for the incubation time, and the profile of the distribution of the concentration of nitrogen over the thickness of the nitrided layer is assumed to be nonlinear. The model is verified by comparing the values calculated within different kinetic approaches to experimental values of the thickness of nitrided layer. The effect of the nitriding potential on the kinetics of gas nitriding of Armco iron at 550 degrees C is studied. The coincidence between the calculated and the experimental data is good.