Characterization of plasma-nitrided iron by XRD, SEM and XPS

The plasma nitriding technique has been used to improve the tribological and mechanical properties of materials, especially iron-based alloys. In this work, the pulsed glow discharge (PGD) technique was used for nitriding pure iron. Three samples were nitrided in a gas mixture of 80 vol.% H 2 and 20...

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Veröffentlicht in:Surface & coatings technology 2004-05, Vol.183 (1), p.10-17
Hauptverfasser: Gontijo, L.C., Machado, R., Miola, E.J., Casteletti, L.C., Nascente, P.A.P.
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Sprache:eng
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Zusammenfassung:The plasma nitriding technique has been used to improve the tribological and mechanical properties of materials, especially iron-based alloys. In this work, the pulsed glow discharge (PGD) technique was used for nitriding pure iron. Three samples were nitrided in a gas mixture of 80 vol.% H 2 and 20 vol.% N 2 under a pressure of 400 Pa, discharge frequency of 9 kHz, and temperature of 580 °C. Samples A, B and C were nitrided for 30 min, 60 min and 90 min, respectively. The nitrided iron samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed differences in the surface morphologies among the samples. XRD identified the γ′-Fe 4N and ε-Fe 2–3N phases in all samples. The Rietveld analysis was performed in order to investigate the concentration variations of the phases as a function of nitriding time. XPS was employed to obtain chemical-state and semi-quantitative information, and revealed a thin film of Fe 2O 3 covering a Fe 3O 4 layer formed on top of the Fe 2–3N and Fe 4N layers.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2003.06.026