Modeling surface processes and kinetics of compound layer formation during plasma nitriding of pure iron

Abstract

Different approaches have been developed concerning growth description of the compact nitride layers, especially those produced by ammonia. Nitriding by plasma uses a glow discharge technology to introduce nitrogen to the surface which in turn diffuses itself into the material. During this process, the ion bombardment causes sputtering of the specimen surface. This paper presents a mathematical model of compound layer formation during plasma nitriding of pure iron. The model takes into account the erosion effect at the plasma-solid interface due to sputtering. This erosion effect is computer simulated and adjusted in order to consider its contribution to the study of layer growth kinetics. The model is presented as a moving boundary diffusion problem, which considers the observed qualitative behavior of the process.