Growth of nitrided phases in pure ARMCO iron obtained by the powder nitriding process
Abstract
The present work studies the growth of iron nitride layer produced by powder pack nitriding process on the surface of a pure iron Armco. The powder pack nitriding process uses nitrogen rich powder (CaCN2). The variables used in this study were four values of temperature (773, 798, 823 and 848 K) with five treatment times (2, 4, 6, 8 and 12 h) and three activator/powder ratios (0.20, 0.25 and 0.35) were used for the set of experimental conditions of the powder-pack nitriding process. Using the mass balance equations at interfaces growth ɛ-Fe2N1-y/γ´-Fe4N1-x y γ´-Fe4N1-x/Fe, mobility of boron it was determined on the surface of the substrate (DE-Fe2N1-y and Dy'-Fe4N1-x ), considering the influence of the incubation times for each phase of growth (tE-Fe2N1-y y ty'-Fe4N1-x). To validate the proposed diffusion model, the simulated value for the thickness of the ɛ-Fe2N1-yy layers γ'-Fe4N1-x was compared with an experimental value respectively. The morphology of the layer was observed by Scanning Electron Microscopy (SEM) and Optical Microscopy. The ɛ-Fe2N1-y and γ´-Fe4N1-x phases were identified by x-ray diffraction method.
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