Mathematical Models and Computer Simulation of Nitrogen Concentration Profiles in Pulse Ion Nitrided Layers

The nitrogen concentration profiles in surface layers and surface phase structures were accurately measured respectively using the glow discharge spectrometry and X-ray Diffractometer after the specimens had been pulse ion nitrided at 500℃ for 0.2-8h The results show that the compound layer growth, which is different from that of conventional DC nitriding, conforms to parabolic law At the same time the surface nitrogen concentration change little with increasing the nitriding time, at least it is so when the treating time is longer than 0.2h In addition, the mathematical models of nitrogen concentration profiles in ε -Fe2~3N,γ-Fe4N and α -Fe phases have been established. Using them the nitrogen concentration profiles in nitrided layers were simulated. Results show that the simulated curves coincide quite well with the experimental data.