Mathematical simulation of the layer growth kinetics during post-discharge nitriding: From early stage to quasi-steady stage
✍ Scribed by F. Castillo; J. Oseguera; A. Gómez; A. Fraguela
- Publisher
- Elsevier Science
- Year
- 2008
- Tongue
- English
- Weight
- 568 KB
- Volume
- 203
- Category
- Article
- ISSN
- 0257-8972
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✦ Synopsis
Nitriding by microwave post-discharge process involves molecular nitrogen dissociation. It has been observed that nitrogen flux from surface to solid during the early stage does not follow a parabolic regime and that the growth rate of concomitant nitride layers is sensitive to atomic nitrogen concentration on the surface. In this work a mathematical model has been developed in order to describe the kinetics of the compound layer formation during a post-discharge nitriding process. The model is related to a moving boundary value problem and considers different stages: diffusion process, formation of the layers, layer growth and quasi-stabilization of the layer growth. An analytical approximate solution of Goodman's type is sought and representations of the motion of the interfaces and the nitrogen concentration profiles are analyzed.