Modeling of nitride layer formation during plasma nitriding of iron

A generalized Wagner diffusion model is used to analyze the layer formation and growth in definite experiments on plasma nitriding of pure iron. It is demonstrated that the model is able to predict the compound layer composition and can be used as a method for calculation of the effective diffusion coefficients in the first sub-layer of the compound zone, providing that the concentration ranges and the effective diffusion coefficients of the nitrogen in the other sub-layers, as well as the total compound layer thickness as a function of time, are known. The model predicts the violation of the parabolic law of growth for both the compound and diffusion zone of the plasma nitrided iron. (C) 1999 Elsevier Science B.V. All rights reserved.