Modeling of Nitrogen Penetration in Medical Grade CoCrMo Alloy during Plasma Nitriding
Keywords:CoCr alloy, nitriding, concentration dependant diffusion, trapping-detrapping model, kinetic modeling
For analysis of plasma nitriding process and nitrogen penetration into CoCrMo alloy the trapping-detrapping model is applied. This model is commonly used for analysis of stainless steel nitriding, however, in this work it is shown that the same nitrogen penetration mechanism takes place in CoCrMo alloys. From the fitting of experimental curves, taken from literature, it is found by the proposed model that diffusion coefficient depends on nitrogen concentration according to Einstein-Smoluchowski relation D µ 1/CN. The diffusion coefficients for 400oC temperature nitriding of in CoCrMo are calculated. The shape of nitrogen depth profile curves are analyzed showing influence of different parameters such as detrapping activation energy, chromium concentration, etc.
The copyrights for articles in this journal are retained by the author(s), with first publication rights granted to the journal. By virtue of their appearance in this open-access journal, articles are free to use with proper attribution in educational and other non-commercial settings.